INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS.
The interaction of K2PdCl4 with ethylenediaminetetra(methylenephosphonic) (edtmp, H8L1) and pentamethylenediaminetetra(methylenephosphonic) (pendtmp, H8L2) acids in solutions with physiological chloride ion concentration (0.15 mol L-1KCl) was studied by pH-potentiometry, UV-Vis and NMR spectroscopy...
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| Дата: | 2024 |
|---|---|
| Автори: | , , , , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
V.I.Vernadsky Institute of General and Inorganic Chemistry
2024
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Репозитарії
Ukrainian Chemistry Journal| _version_ | 1871466051478224896 |
|---|---|
| author | Kozachkova, Oleksandra Tsaryk, Nataliya Pekhnyo, Vasyl Trachevskij, Volodymyr Kocharovska, Olga Palchyk, Oleksii |
| author_facet | Kozachkova, Oleksandra Tsaryk, Nataliya Pekhnyo, Vasyl Trachevskij, Volodymyr Kocharovska, Olga Palchyk, Oleksii |
| author_institution_txt_mv | [
{
"author": "Oleksandra Kozachkova",
"institution": "V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine"
},
{
"author": "Nataliya Tsaryk",
"institution": "V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine"
},
{
"author": "Vasyl Pekhnyo",
"institution": "V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine"
},
{
"author": "Volodymyr Trachevskij",
"institution": "Technical centre of NAS of Ukraine, National Academy of Sciences of Ukraine"
},
{
"author": "Olga Kocharovska",
"institution": "Pokrovs’ka St., 04079 Kyiv, Ukraine; National Technical University of Ukraine \"Igor Sikorsky Kyiv Polytechnic Institute\"), 37 Prosp. Beresteiskyi (Peremohy), 03056 Kyiv, Ukraine"
},
{
"author": "Oleksii Palchyk",
"institution": "V. I. Vernadskii Institute of General and Inorganic Chemistry of the Ukrainian National Academy of Sciences, Akad. Palladin Avenue 32\/34, Kyiv 03142, Ukraine"
}
] |
| author_sort | Kozachkova, Oleksandra |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:54Z |
| description | The interaction of K2PdCl4 with ethylenediaminetetra(methylenephosphonic) (edtmp, H8L1) and pentamethylenediaminetetra(methylenephosphonic) (pendtmp, H8L2) acids in solutions with physiological chloride ion concentration (0.15 mol L-1KCl) was studied by pH-potentiometry, UV-Vis and NMR spectroscopy. It was established that in the Pd(II)-edtmp and Pd(II)-pendtmp systems at a metal-ligand ratio of 1:1, complexes of equimolar composition [Pd(H4L1,2)Cl2]4-, [Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- are formed, for which formation constants were calculated, and distribution diagrams of equilibrium concentrations were constructed as a function of solution pH. A bidentate mode of coordination of edtmp and pendtmp to the central metal ion by the nitrogen and oxygen atoms of the phosphonate group in the [Pd(H4L1,2)Cl2]4- complex and a tridentate mode by a nitrogen atom and two oxygen atoms of two phosphonate groups of one aminodi(methylphosphonate) moiety of ligands in complexes of the compositions [Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-,[Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- were determined. At the concentration ratio Pd(II)-edtmp=2:1 at pH>3, sparingly soluble hydrolysis products were formed in solutions, indicating the absence of interaction between the non-coordinated aminodi(methylphosphonate) moiety of the ligand and Pd(II) to form a binuclear complex. In contrast to edtmp, the system K2[PdCl4]-pendtmp at a 2:1 ratio exhibited the formation of binuclear complexes [Pd2(H3L2)Cl4]5-, [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6-. In the [Pd2(H3L2)Cl4]5- complex, two aminodi(methylphosphonate) moieties of pendtmp are coordinated to two Pd(II) ions in a bidentate mode by nitrogen and oxygen atoms of the phosphonate group, and in the complexes [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6-, they are coordinated in a tridentate mode by a nitrogen atom and two oxygen atoms of two phosphonate groups. |
| doi_str_mv | 10.33609/2708-129X.90.6.2024.47-58 |
| first_indexed | 2025-09-24T17:43:57Z |
| format | Article |
| fulltext |
47
UDC 54-386+661.898 doi: 10.33609/2708-129X.90.6.2024.47-58
INTERACTION OF PALLADIUM(II) WITH
ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS.
O.M. Kozachkovaa, N.V. Tsaryka, O.V. Palchyka, V.I. Pekhnyoa ,
V.V. Trachevskyib, O.P. Kachorovskac
aVernadsky Institute of general and inorganic chemistry of the Ukrainian National Academy of
Sciences,
32/34 prosp. Acad. Palladina, 03142 Kyiv, Ukraine;
bTechnical center of NAS of Ukraine, National Academy of Sciences of Ukraine,
13 vul. Pokrovska, 04079 Kyiv, Ukraine;
сNational Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute",
37 prosp. Beresteiskyi, 03056 Kyiv, Ukraine
*е-mail: akozachkova62@gmail.com
The interaction of K2PdCl4 with ethylenediaminetetra(methylenephosphonic) (edtmp, H8L
1) and
pentamethylenediaminetetra(methylenephosphonic) (pendtmp, H8L
2) acids in solutions with phy
siological chloride ion concentration (0.15 mol L-1 KCl) was studied by pH-potentiometry, UV-Vis
and NMR spectroscopy. It was established that in the Pd(II)-edtmp and Pd(II)-pendtmp systems at
a metal-ligand ratio of 1:1, complexes of equimolar composition [Pd(H4L
1,2)Cl2]
4-, [Pd(H3L
1,2)Cl]4-,
[Pd(H2L
1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- are formed, for which formation constants were
calculated, and distribution diagrams of equilibrium concentrations were constructed as a function of
solution pH. A bidentate mode of coordination of edtmp and pendtmp to the central metal ion by the
nitrogen and oxygen atoms of the phosphonate group in the [Pd(H4L
1,2)Cl2]
4- complex and a tridentate
mode by a nitrogen atom and two oxygen atoms of two phosphonate groups of one aminodi(me
thylphosphonate) moiety of ligands in complexes of the compositions [Pd(H3L
1,2)Cl]4-, [Pd(H2L
1,2)Cl]5-,
[Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- were determined. At the concentration ratio Pd(II)-edtmp=2:1 at
pH>3, sparingly soluble hydrolysis products were formed in solutions, indicating the absence of inte
raction between the non-coordinated aminodi(methylphosphonate) moiety of the ligand and Pd(II)
to form a binuclear complex. In contrast to edtmp, the system K2[PdCl4]-pendtmp at a 2:1 ratio ex
hibited the formation of binuclear complexes [Pd2(H3L
2)Cl4]
5-, [Pd2(H2L
2)Cl2]
4-, [Pd2(HL2)Cl2]
5-, and
[Pd2(L
2)Cl2]
6-. In the [Pd2(H3L
2)Cl4]
5- complex, two aminodi(methylphosphonate) moieties of pendtmp
are coordinated to two Pd(II) ions in a bidentate mode by nitrogen and oxygen atoms of the phospho
nate group, and in the complexes [Pd2(H2L
2)Cl2]
4-, [Pd2(HL2)Cl2]
5-, and [Pd2(L2)Cl2]
6-, they are coor
dinated in a tridentate mode by a nitrogen atom and two oxygen atoms of two phosphonate groups.
Keywords: aminopolyphosphonates, palladium complexes, formation constants.
48 ISSN 2708-129X. Укр. хім. журн., 2024
INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. INORGANIC CHEMISTRY
INTRODUCTION. The synthesis and in
vestigation of complex compounds of metal
ions with aminopolyphosphonates (APPs) are
of significant interest due to their wide appli
cation in industry, agriculture, and medicine.
The medical application of this class of com
pounds is based on their affinity to the bone
matrix, which determines the ability of phos
phonate-containing compounds to accumu
late in the sites of bone tissue lesion caused by
malignant tumors or metastases [1, 2]. Stable
complexes of ethylenediaminetetra(methylene
phosphonic) acid (edtmp) with radionuclides
153Sm, 166Ho, 177Lu, and 90Y have been synthe
sized as therapeutic agents for the diagnosis
and palliative treatment of patients with bone
lesions [3, 4]. This has led to numerous stu
dies on the complex formation of APPs with a
range of lanthanides, alkaline earth metals, and
3d-metals, which involved determining the sta
bility of the formed complexes, the composi
tion of their inner coordination sphere, and the
mode of ligand coordination to the metal ion.
The combination of platinum-group metals
with APPs in a complex offers the potential for
directed delivery of cytotoxic agents to bone
lesions, offering a promising avenue for the
creation of potent anti-tumor treatments. No
tably, among the platinum group metals, pal
ladium(II) compounds demonstrate cytotoxic
effects comparable to platinum compounds but
with markedly reduced toxicity [5]. In review
articles on chemotherapeutic agents based on
Pd(II) complexes with bulky aromatic or ali
phatic nitrogen- and sulfur-containing ligands,
the importance of the strategy for developing
anticancer drugs based on them is emphasized
[6, 7].
In the previous article, the results of the
study of the acid-base properties of ethylene
diaminetetra(methylenephosphonic) acid
(edtmp, H8L
1) and pentamethylenediamine
tetra(methylenephosphonic) acid (pendtmp,
H8L
2) were presented [8]. The presence of four
acidic PO3
2- groups and two basic nitrogen
atoms in the molecules of edtmp and pendtmp
determines diverse possibilities for their coor
dination to Pd(II), formation both of complex
es with ligand anions with different degrees of
protonation, and binuclear complexes.
n=2 (edtmp), 5 (pendtmp)
In this work we have studied reactions of
Pd(II) with edtmp and pendtmp acids in solu
tions with chloride ion concentration (0.15
mol L-1) at Pd(II):ligand ratios of 1:1 and 2:1.
EXPERIMENT AND DISCUSSIONS OF
THE RESULTS. N,N,N’,N’-ethylenediamine
tetra(methylenephosphonic) acid hydrate,
obtained from 'abcr' Germany, and N,N,N’,N’-
pentamethylenediaminetetra(methylenephos
phonic) acid (pendtmp) synthesized via a
modified Kabachnik-Fields reaction [8] were
used in the work. The starting salt K2PdCl4 was
prepared as described in [9].
All the experiments were accomplished in
aqueous solution at a constant temperature
of 20.0 ± 0.1 ˚C in a temperature-controlled
vessel and constant concentrations of KCl
(0.15 mol L-1). The pH measurements of solu
tions were performed using a 827 рН lab me
ter (Metrohm). Standard buffer solutions with
pH 1.68, 6.86, and 9.18 were used for pH meter
calibration. The spectrophotometric studies
The combination of platinum-group metals with APPs in a complex offers the potential for
directed delivery of cytotoxic agents to bone lesions, offering a promising avenue for the creation of
potent anti-tumor treatments. Notably, among the platinum group metals, palladium(II) compounds
demonstrate cytotoxic effects comparable to platinum compounds but with markedly reduced
toxicity [5]. In review articles on chemotherapeutic agents based on Pd(II) complexes with bulky
aromatic or aliphatic nitrogen- and sulfur-containing ligands, the importance of the strategy for
developing anticancer drugs based on them is emphasized [6, 7].
In the previous article, the results of the study of the acid-base properties of
ethylenediaminetetra(methylenephosphonic) acid (edtmp, H8L1) and
pentamethylenediaminetetra(methylenephosphonic) acid (pendtmp, H8L2) were presented [8]. The
presence of four acidic PO3
2- groups and two basic nitrogen atoms in the molecules of edtmp and
pendtmp determines diverse possibilities for their coordination to Pd(II), formation both of
complexes with ligand anions with different degrees of protonation, and binuclear complexes.
n=2 (edtmp), 5 (pendtmp)
In this work we have studied reactions of Pd(II) with edtmp and pendtmp acids in solutions
with chloride ion concentration (0.15 mol L-1) at Pd(II):ligand ratios of 1:1 and 2:1.
EXPERIMENT AND DISCUSSIONS OF THE RESULTS. N,N,N’,N’-
ethylenediaminetetra(methylenephosphonic) acid hydrate, obtained from 'abcr' Germany, and
N,N,N’,N’-pentamethylenediaminetetra(methylenephosphonic) acid (pendtmp) synthesized via a
modified Kabachnik-Fields reaction [8] were used in the work. The starting salt K2PdCl4 was
prepared as described in [9].
All the experiments were accomplished in aqueous solution at a constant temperature of
20.0 ± 0.1 ˚C in a temperature-controlled vessel and constant concentrations of KCl (0.15 mol L-1).
The pH measurements of solutions were performed using a 827 рН lab meter (Metrohm). Standard
buffer solutions with pH 1.68, 6.86, and 9.18 were used for pH meter calibration. The
spectrophotometric studies were conducted for a series of solutions with metal:ligand ratios of 1:1
and 2:1 at Pd(II) concentrations of 2.5.10-3 mol L-1 and 5.10-3 mol L-1. The electronic absorption
spectra (EAS) were recorded using a Specord-M40 spectrophotometer in a quartz cuvette (l=0.2 cm
and 1 cm). The nuclear magnetic resonance (NMR) spectra (31P-{H}) were recorded on a Bruker
AVANCE 400 spectrometer without deuterium stabilization of the resonance conditions. 31P NMR
chemical shifts values were determined relative to external 85% H3PO4. The pH measurements,
recording of EASs, and NMR spectra were conducted 24 hours after the preparation of a series of
solutions containing palladium(II) and ligand.
The formation constants of complexes were calculated using the PSEQUAD program [10]
based on pH-potentiometry and spectrophotometry data of two parallel series from the formula:
β=[MxLyHzClq]/[M]x[L]y[H]z[Cl]q and using formation constants of protonated forms of the
alkylendiaminetetra(methylenephosphonic) acids understudy. The composition of the inner
coordination sphere (chromophore) of the palladium(II) complexes was determined by comparing
the positions of the absorption band maxima in the EASs (vexp.) with the position of the maximum
calculated by formula (1):
49https://ucj.org.ua
O.M. Kozachkova, N.V. Tsaryk, O.V. Palchyk, V.I. Pekhnyo, V.V. Trachevskyi, O.P. Kachorovska UCJ № 6 / Vol. 90
were conducted for a series of solutions with
metal:ligand ratios of 1:1 and 2:1 at Pd(II) con
centrations of 2.5.10-3 mol L-1 and 5.10-3 mol L-1.
The electronic absorption spectra (EAS) were
recorded using a Specord-M40 spectropho
tometer in a quartz cuvette (l=0.2 cm and
1 cm). The nuclear magnetic resonance (NMR)
spectra (31P-{H}) were recorded on a Bruker
AVANCE 400 spectrometer without deuteri
um stabilization of the resonance conditions.
31P NMR chemical shifts values were deter
mined relative to external 85% H3PO4. The pH
measurements, recording of EASs, and NMR
spectra were conducted 24 hours after the
preparation of a series of solutions containing
palladium(II) and ligand.
The formation constants of complexes were
calculated using the PSEQUAD program [10]
based on pH-potentiometry and spectropho
tometry data of two parallel series from the
formula: β=[MxLyHzClq]/[M]x[L]y[H]z[Cl]q and
using formation constants of protonated forms
of the alkylendiaminetetra(methylenephos
phonic) acids understudy. The composition of
the inner coordination sphere (chromophore)
of the palladium(II) complexes was deter
mined by comparing the positions of the ab
sorption band maxima in the EASs (vexp.) with
the position of the maximum calculated by
formula (1):
νcalc.=n1ν(Cl)+n2ν(Oaqua)+
+n3ν(Namin.)+n4ν(Ophosphon.) (1),
where ni is the number of donor atoms of each
type; ν is the increment value for a donor atom
of each type (cm-1): ν(Cl) = 5170, ν(Oaqua) =
6580, ν(Namin.) = 8460 and ν(Ophosphon.) = 6831
[11, 12].
The interaction of K2PdCl4 with edtmp.
The electronic absorption spectra (EASs)
of solutions of the K2PdCl4-edtmp=1:1 system
upon addition of 1 to 8 equivalents of base in the
pH range of 1.92–9.21 are shown in Figure 1.
νcalc.=n1ν(Cl)+n2ν(Oaqua)+n3ν(Namin.)+n4ν(Ophosphon.) (1),
where ni is the number of donor atoms of each type; ν is the increment value for a donor atom of
each type (cm-1): ν(Cl) = 5170, ν(Oaqua) = 6580, ν(Namin.) = 8460 and ν(Ophosphon.) = 6831 [11, 12].
The interaction of K2PdCl4 with edtmp.
The electronic absorption spectra (EASs) of solutions of the K2PdCl4-edtmp=1:1 system
upon addition of 1 to 8 equivalents of base in the pH range of 1.92–9.21 are shown in Figure 1.
Fig. 1. EASs of the K2PdCl4-edtmp=1:1 system (CPd(II)=Cedtmp=5.10-3 mol L-1, СKСl=0.15 mol L-1, рН: 1.92
(1); 2.13 (2); 2.53 (3); 3.28 (4);4.40 (5); 6.41 (6); 7.21 (7); 9.21 (8)).
The position of the absorption band maximum in the EASs of solutions with pH 1.92 and
2.13 at 25800 cm-1 indicates the formation of a complex with the chromophore composition
[Pd;Namin.; Ophosphon.; 2Cl] (νcalc.=25600 cm-1). In this complex, the ligand is bidentately coordinated
to Pd(II) by the nitrogen and oxygen atoms of the phosphonate group. The formation constant of
this complex was determined from spectrophotometry and pH-potentiometry data of solutions with
constant concentration of K2PdCl4 and concentration of edtmp varying to the metal-to-ligand ratio
of 1:1 (see Table 1).
The shift of the absorption band maximum to 27600 cm-¹ upon pH increase to 4.40 can be
explained by the formation of a complex with chromophore of the composition [Pd; Namin.;
2Ophosphon.; Cl] (νcalc.=27300 cm-¹), where edtmp coordinates to Pd(II) in a tridentate manner
through a nitrogen atom and two oxygen atoms of the phosphonate groups of one
aminodi(methylenephosphonate) moiety.
Fig. 1. EASs of the K2PdCl4-edtmp=1:1 system (CPd(II)=Cedtmp=5.10-3 mol L-1, СKСl=0.15 mol L-1,
рН: 1.92 (1); 2.13 (2); 2.53 (3); 3.28 (4);4.40 (5); 6.41 (6); 7.21 (7); 9.21 (8)).
50 ISSN 2708-129X. Укр. хім. журн., 2024
INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. INORGANIC CHEMISTRY
The position of the absorption band maxi
mum in the EASs of solutions with pH 1.92
and 2.13 at 25800 cm-1 indicates the formation
of a complex with the chromophore composi
tion [Pd;Namin.; Ophosphon.; 2Cl] (νcalc.=25600 cm-1).
In this complex, the ligand is bidentately coor
dinated to Pd(II) by the nitrogen and oxygen
atoms of the phosphonate group. The forma
tion constant of this complex was determined
from spectrophotometry and pH-potentio
metry data of solutions with constant concen
tration of K2PdCl4 and concentration of edtmp
varying to the metal-to-ligand ratio of 1:1 (see
Table 1).
The shift of the absorption band maximum
to 27600 cm-¹ upon pH increase to 4.40 can be
explained by the formation of a complex with
chromophore of the composition [Pd; Namin.;
2Ophosphon.; Cl] (νcalc.=27300 cm-¹), where
edtmp coordinates to Pd(II) in a tridentate
manner through a nitrogen atom and two oxy
gen atoms of the phosphonate groups of one
aminodi(methylenephosphonate) moiety.
[Pd(H4L
1)Cl2]
4- [Pd(H3L
1)Cl]4-
[Pd(H4L1)Cl2]4- [Pd(H3L1)Cl]4-
The invariable position of the absorption maximum at 27600 cm-1 in the EASs at pH 4.40 –
9.11 indicates the formation of a number of complexes with the same chromophore upon sequential
deprotonation of the coordinated ligand.
Table 1.
Calculated formation constants of complexes of Pd(II) with edtmp and pendtmp.
The composition of
complexes*
lgβ
[Pd(H4L1)Cl2]4- 52.41 (9)
[Pd(H3L1)Cl]4- 47.84 (9)
[Pd(H2L1)Cl]5- 41.60 (8)
[Pd(HL1)Cl]6- 34.24 (6)
[Pd(L1)Cl]7- 26.40 (7)
{Pd(H2L2)Cl2} 37.20 (6)
{Pd(HL2)Cl} 31.31 (4)
{Pd(L2)Cl} 23.60 (5)
{Pd2(HL2)Cl2} 46.17 (9)
{Pd2LCl2} 41.87 (8)
{Pd2LH-1} 34.60 (8)
{Pd2LH-2} 25.32 (8)
* - in [ ] is given the actual composition of complexes, and in { } the conditional composition of complexes.
The calculated formation constants of Pd(II) complexes with edtmp were used to construct
distribution diagrams of their equilibrium concentrations as a function of pH (Fig. 2).
[Pd(H4L1)Cl2]4- [Pd(H3L1)Cl]4-
The invariable position of the absorption maximum at 27600 cm-1 in the EASs at pH 4.40 –
9.11 indicates the formation of a number of complexes with the same chromophore upon sequential
deprotonation of the coordinated ligand.
Table 1.
Calculated formation constants of complexes of Pd(II) with edtmp and pendtmp.
The composition of
complexes*
lgβ
[Pd(H4L1)Cl2]4- 52.41 (9)
[Pd(H3L1)Cl]4- 47.84 (9)
[Pd(H2L1)Cl]5- 41.60 (8)
[Pd(HL1)Cl]6- 34.24 (6)
[Pd(L1)Cl]7- 26.40 (7)
{Pd(H2L2)Cl2} 37.20 (6)
{Pd(HL2)Cl} 31.31 (4)
{Pd(L2)Cl} 23.60 (5)
{Pd2(HL2)Cl2} 46.17 (9)
{Pd2LCl2} 41.87 (8)
{Pd2LH-1} 34.60 (8)
{Pd2LH-2} 25.32 (8)
* - in [ ] is given the actual composition of complexes, and in { } the conditional composition of complexes.
The calculated formation constants of Pd(II) complexes with edtmp were used to construct
distribution diagrams of their equilibrium concentrations as a function of pH (Fig. 2).
Table 1.
Calculated formation constants of com-
plexes of Pd(II) with edtmp and pendtmp.
The composition of
complexes*
lgβ
[Pd(H4L
1)Cl2]
4- 52.41 (9)
[Pd(H3L
1)Cl]4- 47.84 (9)
[Pd(H2L
1)Cl]5- 41.60 (8)
[Pd(HL1)Cl]6- 34.24 (6)
[Pd(L1)Cl]7- 26.40 (7)
{Pd(H2L
2)Cl2} 37.20 (6)
{Pd(HL2)Cl} 31.31 (4)
{Pd(L2)Cl} 23.60 (5)
{Pd2(HL2)Cl2} 46.17 (9)
{Pd2LCl2} 41.87 (8)
{Pd2LH-1} 34.60 (8)
{Pd2LH-2} 25.32 (8)
* - in [ ] is given the actual composition of complexes,
and in { } the conditional composition of complexes.
The invariable position of the absorption
maximum at 27600 cm-1 in the EASs at pH
4.40 – 9.11 indicates the formation of a num
ber of complexes with the same chromophore
upon sequential deprotonation of the coordi
nated ligand.
The calculated formation constants of Pd(II)
complexes with edtmp were used to construct
distribution diagrams of their equilibrium
concentrations as a function of pH (Fig. 2).
As evident from the diagram, complex
formation in the system K2[PdCl4]–edtmp
occurs already in strongly acidic conditions
at pH<2. At physiological pH values, the
dominant complexes are [Pd(H2L
1)Cl]5- and
[Pd(HL1)Cl]6-.
51https://ucj.org.ua
O.M. Kozachkova, N.V. Tsaryk, O.V. Palchyk, V.I. Pekhnyo, V.V. Trachevskyi, O.P. Kachorovska UCJ № 6 / Vol. 90
Fig. 2. Equilibrium concentration distribution diagram for the complexes formed in
the K2PdCl4–edtmp=1:1 system (СKСl=0.15 mol L-1; [PdCl4]
2- (1); [PdCl3]
- (2); [Pd(H4L
1)Cl2]
4- (3);
[Pd(H3L
1)Cl]4- (4); [Pd(H2L
1)Cl]5- (5); [Pd(HL1)Cl]6- (6); [Pd(L1)Cl]7- (7)).
Fig. 2. Equilibrium concentration distribution diagram for the complexes formed in the K2PdCl4–edtmp=1:1
system (СKСl=0.15 mol L-1; [PdCl4]2- (1); [PdCl3]- (2); [Pd(H4L1)Cl2]4- (3); [Pd(H3L1)Cl]4- (4); [Pd(H2L1)Cl]5-
(5); [Pd(HL1)Cl]6- (6); [Pd(L1)Cl]7- (7)).
As evident from the diagram, complex formation in the system K2[PdCl4]–edtmp occurs
already in strongly acidic conditions at pH<2. At physiological pH values, the dominant complexes
are [Pd(H2L1)Cl]5- and [Pd(HL1)Cl]6-.
To investigate the potential formation of a binuclear complex upon binding by excess Pd(II)
the free aminodi(methylenephosphonate) moiety of edtmp, complexation reactions were studied in
the system K2[PdCl4]–edtmp=2:1. In solutions of this system under the conditions of double excess
of Pd(II) at pH>3, the formation of sparingly soluble hydrolysis products was observed, indicating
the absence of interaction between the free aminodi(methylenephosphonate) moiety of the ligand
and excess Pd(II) to form a binuclear complex. In this case, the absence of binuclear complex
formation can be explained by steric hindrances.
The proposed scheme of complex formation in the K2PdCl4–edtmp=1:1 system was
confirmed by 31P NMR spectroscopy data (Fig. 3).
To investigate the potential formation of a bi
nuclear complex upon binding by excess Pd(II)
the free aminodi(methylenephosphonate)
moiety of edtmp, complexation reactions were
studied in the system K2[PdCl4]–edtmp=2:1. In
solutions of this system under the conditions of
double excess of Pd(II) at pH>3, the formation
of sparingly soluble hydrolysis products was
observed, indicating the absence of interaction
between the free aminodi(methylenephospho
nate) moiety of the ligand and excess Pd(II) to
form a binuclear complex. In this case, the ab
sence of binuclear complex formation can be
explained by steric hindrances.
The proposed scheme of complex formation
in the K2PdCl4–edtmp=1:1 system was con
firmed by 31P NMR spectroscopy data (Fig. 3).
In the 31P NMR spectra of solutions in the
pH range of 1.92 to 3.28, three signals of phos
phorus nuclei were observed. The signals at
δP~41.0 ppm and δP~8.8 ppm, which exhibit
equal integral intensities, correspond to the
coordinated and free phosphonate groups of
one aminodi(methylenephosphonate) moiety
in the complex [Pd(H4L
1)Cl2]
4-. The signal of
phosphorus nuclei at δP~10.5 ppm, whose in
tegral intensity is twice as high, corresponds to
the two phosphonate groups of the free ami
nodi(methylenephosphonate) moiety of the li
gand. In the 31P NMR spectra of solutions with
pH>4.40, two signals of phosphorus nuclei
with equal integral intensities were observed
upon the formation of complexes with edtmp
tridentately coordinated to the central metal
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INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. INORGANIC CHEMISTRY
ion. The signal at δP~33.9 ppm corresponds
to the two coordinated phosphonate groups of
the one aminodi(methylphosphonate) moiety,
while the signal at δP~7.6 ppm corresponds to
non-coordinated phosphonate groups of an
other aminodi(methylphosphonate) moiety of
the ligand. Thus, the sequence of complex for
mation in the system K2[PdCl4]–edtmp=1:1,
as depicted by the equilibrium concentration
distribution diagram for complexes (Fig. 2),
is consistent with the 31P NMR spectroscopy
data.
Fig. 3. 31P-{H} NMR spectra of the K2PdCl4–edtmp=1:1 system (CPd(II)=Cedtmp=5.10-3 mol L-1, pH: 1.92 (1);
2.13 (2); 2.53 (3); 3.28 (4); 4.40 (5); 6.41 (6); 7.21 (7); 9.21 (8)).
In the 31P NMR spectra of solutions in the pH range of 1.92 to 3.28, three signals of
phosphorus nuclei were observed. The signals at δP~41.0 ppm and δP~8.8 ppm, which exhibit
equal integral intensities, correspond to the coordinated and free phosphonate groups of one
aminodi(methylenephosphonate) moiety in the complex [Pd(H4L1)Cl2]4-. The signal of phosphorus
nuclei at δP~10.5 ppm, whose integral intensity is twice as high, corresponds to the two
phosphonate groups of the free aminodi(methylenephosphonate) moiety of the ligand. In the 31P
NMR spectra of solutions with pH>4.40, two signals of phosphorus nuclei with equal integral
intensities were observed upon the formation of complexes with edtmp tridentately coordinated to
the central metal ion. The signal at δP~33.9 ppm corresponds to the two coordinated phosphonate
groups of the one aminodi(methylphosphonate) moiety, while the signal at δP~7.6 ppm corresponds
to non-coordinated phosphonate groups of another aminodi(methylphosphonate) moiety of the
ligand. Thus, the sequence of complex formation in the system K2[PdCl4]–edtmp=1:1, as depicted
by the equilibrium concentration distribution diagram for complexes (Fig. 2), is consistent with the
31P NMR spectroscopy data.
Interaction of K2PdCl4 with pendtmp.
In the EASs of the K2[PdCl4]–pendtmp=1:1 system upon pH increase from 2.50 to 4.10, a
shift of the absorption band with a maximum at 21600 cm-1, corresponding to a mixture of [PdCl4]2-
and [PdCl3H2O]-, to 25600 cm-1 was observed, indicating the formation of a complex with
chromophore of the composition [Pd; Namin.; Ophosphon.; 2Cl] (Fig. 4a). Further shift of the absorption
band maximum to 26900 cm-1, observed upon pH change from 4.99 to 7.73, corresponds to the
formation of complexes with the same chromophore composition [Pd; Namin.; 2Ophosphon.; Cl].
In the pH range of 2.51 to 8.46 of the aqueous solutions of the K2[PdCl4]–pendtmp=2:1
system, changes in the absorption band position similar to those observed in the K2[PdCl4]–
pendtmp=1:1 system were recorded with nearly a twofold increase in the intensity of the absorption
bands with maxima at 25600 cm-1 and 26900 cm-1, respectively (Fig. 4b). This suggests the
Fig. 3. 31P-{H} NMR spectra of the K2PdCl4–edtmp=1:1 system (CPd(II)=Cedtmp=5.10-3 mol L-1,
pH: 1.92 (1); 2.13 (2); 2.53 (3); 3.28 (4); 4.40 (5); 6.41 (6); 7.21 (7); 9.21 (8)).
Interaction of K2PdCl4 with pendtmp.
In the EASs of the K2[PdCl4]–pendtmp=1:1
system upon pH increase from 2.50 to 4.10, a
shift of the absorption band with a maximum
at 21600 cm-1, corresponding to a mixture of
[PdCl4]
2- and [PdCl3H2O]-, to 25600 cm-1 was
observed, indicating the formation of a com
plex with chromophore of the composition [Pd;
Namin.; Ophosphon.; 2Cl] (Fig. 4a). Further shift of
the absorption band maximum to 26900 cm-1,
observed upon pH change from 4.99 to 7.73,
corresponds to the formation of complexes
with the same chromophore composition [Pd;
Namin.; 2Ophosphon.; Cl].
In the pH range of 2.51 to 8.46 of the
aqueous solutions of the K2[PdCl4]–pendt
mp=2:1 system, changes in the absorption
band position similar to those observed in the
53https://ucj.org.ua
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K2[PdCl4]–pendtmp=1:1 system were recor
ded with nearly a twofold increase in the in
tensity of the absorption bands with maxima
at 25600 cm-1 and 26900 cm-1, respective
ly (Fig. 4b). This suggests the formation in
this system of binuclear complexes with the
coordination of two Pd(II) ions to the two
aminodi(methylenephosphonate) moieties of
pendtmp. Thus, binuclear complexes contain
two chromophoric groups each: [Pd; Namin.;
Ophosphon.; 2Cl] or [Pd; Namin.; 2Ophosphon.; Cl].
Fig. 4. EASs of the K2PdCl4-pendtmp system ((а)
CPd(II)=Cpendtmp=2.5.10-3 mol L-1, СKСl=0.15 mol L-1, рН:
2.50 (1); 2.88 (2); 3.22 (3); 3.57 (4);4.10 (5); 4.99
(6); 5.68 (7); 6.41 (8); 7.27 (9); 7.66 (10); 7.73 (11),
(b) CPd(II)=5.10-3 mol L-1, Cpendtmp=2.5.10-3 mol L-1, pH:
2.51 (1); 2.81 (2); 3.09 (3); 3.36 (4);3.61 (5); 3.81
(6); 4.35 (7); 5.43 (8); 7.93 (9); 8.46 (10)).
In Table 1, the conditional composition of
Pd(II) complexes with pendtmp is presented,
for which formation constants were calcula
ted considering the formation constants of the
protonated forms of pendtmp as for a condi
tionally pentadentate acid [8].
Diagrams of equilibrium concentration dis
tribution of complexes as a function of pH were
constructed, based on calculated formation
constants of Pd(II) complexes with pendtmp,
for the systems K2PdCl4-pendtmp=1:1 and 1:2,
which show the conditional and real composi
tions of complexes (Fig. 5).
It is seen from Fig. 5 that complex formation
in the K2PdCl4-pendtmp=1:1 system begins at
pH~3, which is higher than the corresponding
pH value for the K2[PdCl4]-edtmp=1:1 system.
It should be noted that at the same pH values,
the composition of equimolar Pd(II) complex
es with pendtmp contains ligand forms with
higher degree of protonation than in the case
of equimolar complexes of Pd(II) with edtmp.
Formation of equimolar and binuclear com
plexes in the K2[PdCl4]-pendtmp system is
confirmed by 31P NMR spectroscopy data.
In the 31P NMR spectra of solutions of the
system K2[PdCl4]–pendtmp=1:1, the redistri
bution of integral intensity between the sig
nals of phosphorus nuclei of free phosphonate
groups with δP~7.7 ppm and the signals of the
coordinated phosphonate groups with δP~36.5
ppm and δP~33.4 ppm upon pH increase from
2.95 to 3.97 may indicate the formation of com
plexes of the equimolar composition [Pd(H4L
2)
Cl2]
4- with the chromophore [Pd; Namin.; Ophos
phon.; 2Cl] and [Pd(H3L
2)Cl]4- with the chromo
phore [Pd; Namin.; 2Ophosphon.; Cl] (Fig. 6a). The
presence of two signals of phosphorus nuclei
of coordinated phosphonate groups in a down
field region, each of which is a superposition of
formation in this system of binuclear complexes with the coordination of two Pd(II) ions to the two
aminodi(methylenephosphonate) moieties of pendtmp. Thus, binuclear complexes contain two
chromophoric groups each: [Pd; Namin.; Ophosphon.; 2Cl] or [Pd; Namin.; 2Ophosphon.; Cl].
Fig. 4. EASs of the K2PdCl4-pendtmp system ((а) CPd(II)=Cpendtmp=2.5.10-3 mol L-1, СKСl=0.15 mol L-1, рН:
2.50 (1); 2.88 (2); 3.22 (3); 3.57 (4);4.10 (5); 4.99 (6); 5.68 (7); 6.41 (8); 7.27 (9); 7.66 (10); 7.73 (11), (b)
CPd(II)=5.10-3 mol L-1, Cpendtmp=2.5.10-3 mol L-1, pH: 2.51 (1); 2.81 (2); 3.09 (3); 3.36 (4);3.61 (5); 3.81 (6);
4.35 (7); 5.43 (8); 7.93 (9); 8.46 (10)).
In Table 1, the conditional composition of Pd(II) complexes with pendtmp is
presented, for which formation constants were calculated considering the formation constants of the
protonated forms of pendtmp as for a conditionally pentadentate acid [8].
Diagrams of equilibrium concentration distribution of complexes as a function of pH were
constructed, based on calculated formation constants of Pd(II) complexes with pendtmp, for the
systems K2PdCl4-pendtmp=1:1 and 1:2, which show the conditional and real compositions of
complexes (Fig. 5).
b
a
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INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. INORGANIC CHEMISTRY
several signals, may be due to the presence of
several conformational states of the ligand in
the coordination sphere of the complexes [13].
Upon further increase in pH, deprotonation of
the coordinated ligand occurs without change
in the donor composition of the coordination
sphere of the complexes.
Fig. 5. Equilibrium concentration distribution diagrams complexes in the K2PdCl4–pendtmp systems*
((а) K2[PdCl4]–pendtmp=1:1, (b) K2[PdCl4]–pendtmp=2:1. ([PdCl4]
2- (1); [PdCl3]
- (2);
{Pd(H2L
2)Cl2} [Pd(H4L
2)Cl2]
4- (3); {Pd(HL2)} [Pd(H3L
2)Cl]4- (4); {Pd(L2)} [Pd(H2L
2)Cl]5- (5);
{Pd2(HL2)Cl4} [Pd2(H3L
2)Cl4]
5- (6); {Pd2(L2)Cl2} [Pd2(H2L
2)Cl2]
4- (7);
{Pd2(H-1L
2)Cl2) [Pd2(HL2)Cl2]
5- (8); {Pd2(H-2L
2)Cl2} [Pd2(L)Cl2]
6- (9)).
*- in [ ] is given the actual composition of complexes and in { } the conditional composition
of complexes.
Fig. 5. Equilibrium concentration distribution diagrams complexes in the K2PdCl4–pendtmp systems* ((а)
K2[PdCl4]–pendtmp=1:1, (b) K2[PdCl4]–pendtmp=2:1. ([PdCl4]2- (1); [PdCl3]- (2); {Pd(H2L2)Cl2}
[Pd(H4L2)Cl2]4- (3); {Pd(HL2)} [Pd(H3L2)Cl]4- (4); {Pd(L2)} [Pd(H2L2)Cl]5- (5) {Pd2(HL2)Cl4}
[Pd2(H3L2)Cl4]5- (6); {Pd2(L2)Cl2} [Pd2(H2L2)Cl2]4- (7); {Pd2(H-1L2)Cl2) [Pd2(HL2)Cl2]5- (8); {Pd2(H-2L2)Cl2}
[Pd2(L)Cl2]6- (9)).
*- in [ ] is given the actual composition of complexes and in { } the conditional composition of complexes.
It is seen from Fig. 5 that complex formation in the K2PdCl4-pendtmp=1:1 system begins at
pH~3, which is higher than the corresponding pH value for the K2[PdCl4]-edtmp=1:1 system. It
should be noted that at the same pH values, the composition of equimolar Pd(II) complexes with
pendtmp contains ligand forms with higher degree of protonation than in the case of equimolar
complexes of Pd(II) with edtmp. Formation of equimolar and binuclear complexes in the K2[PdCl4]-
pendtmp system is confirmed by 31P NMR spectroscopy data.
In the 31P NMR spectra of solutions of the system K2[PdCl4]–pendtmp=1:1, the
redistribution of integral intensity between the signals of phosphorus nuclei of free phosphonate
groups with δP~7.7 ppm and the signals of the coordinated phosphonate groups with δP~36.5 ppm
and δP~33.4 ppm upon pH increase from 2.95 to 3.97 may indicate the formation of complexes of
the equimolar composition [Pd(H4L2)Cl2]4- with the chromophore [Pd; Namin.; Ophosphon.; 2Cl] and
[Pd(H3L2)Cl]4- with the chromophore [Pd; Namin.; 2Ophosphon.; Cl] (Fig. 6a). The presence of two
signals of phosphorus nuclei of coordinated phosphonate groups in a downfield region, each of
which is a superposition of several signals, may be due to the presence of several conformational
states of the ligand in the coordination sphere of the complexes [13]. Upon further increase in pH,
deprotonation of the coordinated ligand occurs without change in the donor composition of the
coordination sphere of the complexes.
Fig. 5. Equilibrium concentration distribution diagrams complexes in the K2PdCl4–pendtmp systems* ((а)
K2[PdCl4]–pendtmp=1:1, (b) K2[PdCl4]–pendtmp=2:1. ([PdCl4]2- (1); [PdCl3]- (2); {Pd(H2L2)Cl2}
[Pd(H4L2)Cl2]4- (3); {Pd(HL2)} [Pd(H3L2)Cl]4- (4); {Pd(L2)} [Pd(H2L2)Cl]5- (5) {Pd2(HL2)Cl4}
[Pd2(H3L2)Cl4]5- (6); {Pd2(L2)Cl2} [Pd2(H2L2)Cl2]4- (7); {Pd2(H-1L2)Cl2) [Pd2(HL2)Cl2]5- (8); {Pd2(H-2L2)Cl2}
[Pd2(L)Cl2]6- (9)).
*- in [ ] is given the actual composition of complexes and in { } the conditional composition of complexes.
It is seen from Fig. 5 that complex formation in the K2PdCl4-pendtmp=1:1 system begins at
pH~3, which is higher than the corresponding pH value for the K2[PdCl4]-edtmp=1:1 system. It
should be noted that at the same pH values, the composition of equimolar Pd(II) complexes with
pendtmp contains ligand forms with higher degree of protonation than in the case of equimolar
complexes of Pd(II) with edtmp. Formation of equimolar and binuclear complexes in the K2[PdCl4]-
pendtmp system is confirmed by 31P NMR spectroscopy data.
In the 31P NMR spectra of solutions of the system K2[PdCl4]–pendtmp=1:1, the
redistribution of integral intensity between the signals of phosphorus nuclei of free phosphonate
groups with δP~7.7 ppm and the signals of the coordinated phosphonate groups with δP~36.5 ppm
and δP~33.4 ppm upon pH increase from 2.95 to 3.97 may indicate the formation of complexes of
the equimolar composition [Pd(H4L2)Cl2]4- with the chromophore [Pd; Namin.; Ophosphon.; 2Cl] and
[Pd(H3L2)Cl]4- with the chromophore [Pd; Namin.; 2Ophosphon.; Cl] (Fig. 6a). The presence of two
signals of phosphorus nuclei of coordinated phosphonate groups in a downfield region, each of
which is a superposition of several signals, may be due to the presence of several conformational
states of the ligand in the coordination sphere of the complexes [13]. Upon further increase in pH,
deprotonation of the coordinated ligand occurs without change in the donor composition of the
coordination sphere of the complexes.
55https://ucj.org.ua
O.M. Kozachkova, N.V. Tsaryk, O.V. Palchyk, V.I. Pekhnyo, V.V. Trachevskyi, O.P. Kachorovska UCJ № 6 / Vol. 90
Fig. 6. 31P-{H} NMR spectra of the K2[PdCl4]–pendtmp systems ((a) CPd(II)=Cpendtmp=2.10-3 mol L-1, pH:
2.95 (1); 3.27 (2); 3.61 (3); 3.97 (4). (b) CPd(II)=4.10-3 mol L-1, Cpendtmp=2.10-3 mol L-1, рН: 2.28 (1);
3.42 (2); 4.11 (3); 4.69 (4)).
Fig. 6. 31P-{H} NMR spectra of the K2[PdCl4]–pendtmp systems ((a) CPd(II)=Cpendtmp=2.10-3 mol L-1, pH: 2.95
(1); 3.27 (2); 3.61 (3); 3.97 (4). (b) CPd(II)=4.10-3 mol L-1, Cpendtmp=2.10-3 mol L-1, рН: 2.28 (1); 3.42 (2); 4.11
(3); 4.69 (4)).
As can be seen from the 31P NMR spectra of solutions of the K2[PdCl4]–pendtmp=2:1
system in the pH range of 2.28–3.42, in the down field region there are signals of phosphorus nuclei
that correspond to phosphonate groups coordinated to Pd(II), and in the upfield region to the free
phosphonate groups of the ligand (Fig. 6b). The presence of signals from phosphorus nuclei in
coordinated phosphonate groups (δP~36.5 ppm and δP~33.4 ppm) and the absence of signals of
phosphorus nuclei of free phosphonate groups at pH>4.11 indicate the formation of binuclear
complexes with the coordination of two aminodi(methylenephosphonate) moieties of the ligand to
two Pd(II) ions, the donor environment of each of which has the composition [Pd; Namin.; 2Ophosphon.;
Cl].
56 ISSN 2708-129X. Укр. хім. журн., 2024
INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. INORGANIC CHEMISTRY
As can be seen from the 31P NMR spectra of
solutions of the K2[PdCl4]–pendtmp=2:1 sys
tem in the pH range of 2.28–3.42, in the down
field region there are signals of phosphorus
nuclei that correspond to phosphonate groups
coordinated to Pd(II), and in the upfield region
to the free phosphonate groups of the ligand
(Fig. 6b). The presence of signals from phos
phorus nuclei in coordinated phosphonate
groups (δP~36.5 ppm and δP~33.4 ppm) and
the absence of signals of phosphorus nuclei of
free phosphonate groups at pH>4.11 indicate
the formation of binuclear complexes with the
coordination of two aminodi(methylenephos
phonate) moieties of the ligand to two Pd(II)
ions, the donor environment of each of which
has the composition [Pd; Namin.; 2Ophosphon.; Cl].
[Pd2(H3L
2)Cl4]
5- [Pd2(H2L
2)Cl2]
4-
[Pd2(H3L2)Cl4]5- [Pd2(H2L2)Cl2]4-
Binuclear Pd(II) complexes with pendtmp exist in solution as several conformers, as
evidenced by the presence in the 31P NMR spectra of two signals of the phosphorus nuclei of
coordinated phosphonate groups in a down field region.
CONCLUSIONS. The results of the study have shown that in the systems K2[PdCl4]-
edtmp=1:1 and K2[PdCl4]-pendtmp=1:1, complexes of equimolar composition [Pd(H4L1,2)Cl2]4-,
[Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- are formed. Electron and 31P
NMR spectroscopic data indicate the bidentate mode of coordination of edtmp and pendtmp to the
central metal ion via the nitrogen and oxygen atoms of the phosphonate group in the complex
[Pd(H4L1,2)Cl2]4- and a tridentate coordination of ligands by a nitrogen atom and two oxygen atoms
of two phosphonate groups of one aminodi(methylenephosphonate) moiety in the complexes
[Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7-. At a metal concentration ratio
of 2:1 in the case of edtmp, the formation of sparingly soluble hydrolysis products was observed in
solutions, indicating the impossibility of formation of a binuclear complex with the coordination of
the second aminodi(methylenephosphonate) moiety of edtmp by excess Pd(II).
In contrast to edtmp, in the system K2[PdCl4]-pendtmp=2:1, the formation of binuclear
complexes [Pd2(H3L2)Cl4]5-, [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6- was established.
In the complex [Pd2(H3L2)Cl4]5-, two aminodi(methylenephosphonate) moieties of pendtmp
coordinate bidentately to two Pd(II) ions via the nitrogen and oxygen atoms of the phosphonate
group. In the complexes [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6-, two
aminodi(methylphosphonate) moieties of pendtmp coordinate tridentately to two Pd(II) ions via a
nitrogen atom and two oxygen atoms of two phosphonate groups. The possibility of formation of
binuclear complexes during the interaction of Pd(II) with pendtmp is realized due to the remote
location of two aminodi(methylphosphonate) moieties, whereas closely located
aminodi(methylphosphonate) moieties, as in the case of edtmp, hinder the coordination of the
second aminodi(methylphosphonate) moiety by excess Pd(II) due to steric hindrances.
ACKNOWLEDGEMENT. This work was done under the state support according to the
theme “Promising fundamental research and innovative development of nanomaterials and
nanotechnologies for the needs of industry, healthcare and agriculture”, № state registration
0120U102323, 2020-2024.
ВЗАЄМОДІЯ ПАЛАДІЮ(ІІ) З АЛКІЛЕНДІАМІНТЕТРА(МЕТИЛЕНФОСФОНОВИМИ)
КИСЛОТАМИ
О. М. Козачкова1*, Н. В. Царик1, О. В. Пальчик1, В. І. Пехньо1, В. В. Трачевський2, О. П.
Качоровська3.
1Інститут загальної та неорганічної хімії ім. В.І. Вернадського НАН України,
просп. Акад. Палладіна, 32/34, Київ 03142, Україна;
2ТЦ НАН України, вул. Покровська, буд. 13, Київ 04070, Україна;
[Pd2(H3L2)Cl4]5- [Pd2(H2L2)Cl2]4-
Binuclear Pd(II) complexes with pendtmp exist in solution as several conformers, as
evidenced by the presence in the 31P NMR spectra of two signals of the phosphorus nuclei of
coordinated phosphonate groups in a down field region.
CONCLUSIONS. The results of the study have shown that in the systems K2[PdCl4]-
edtmp=1:1 and K2[PdCl4]-pendtmp=1:1, complexes of equimolar composition [Pd(H4L1,2)Cl2]4-,
[Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- are formed. Electron and 31P
NMR spectroscopic data indicate the bidentate mode of coordination of edtmp and pendtmp to the
central metal ion via the nitrogen and oxygen atoms of the phosphonate group in the complex
[Pd(H4L1,2)Cl2]4- and a tridentate coordination of ligands by a nitrogen atom and two oxygen atoms
of two phosphonate groups of one aminodi(methylenephosphonate) moiety in the complexes
[Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7-. At a metal concentration ratio
of 2:1 in the case of edtmp, the formation of sparingly soluble hydrolysis products was observed in
solutions, indicating the impossibility of formation of a binuclear complex with the coordination of
the second aminodi(methylenephosphonate) moiety of edtmp by excess Pd(II).
In contrast to edtmp, in the system K2[PdCl4]-pendtmp=2:1, the formation of binuclear
complexes [Pd2(H3L2)Cl4]5-, [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6- was established.
In the complex [Pd2(H3L2)Cl4]5-, two aminodi(methylenephosphonate) moieties of pendtmp
coordinate bidentately to two Pd(II) ions via the nitrogen and oxygen atoms of the phosphonate
group. In the complexes [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6-, two
aminodi(methylphosphonate) moieties of pendtmp coordinate tridentately to two Pd(II) ions via a
nitrogen atom and two oxygen atoms of two phosphonate groups. The possibility of formation of
binuclear complexes during the interaction of Pd(II) with pendtmp is realized due to the remote
location of two aminodi(methylphosphonate) moieties, whereas closely located
aminodi(methylphosphonate) moieties, as in the case of edtmp, hinder the coordination of the
second aminodi(methylphosphonate) moiety by excess Pd(II) due to steric hindrances.
ACKNOWLEDGEMENT. This work was done under the state support according to the
theme “Promising fundamental research and innovative development of nanomaterials and
nanotechnologies for the needs of industry, healthcare and agriculture”, № state registration
0120U102323, 2020-2024.
ВЗАЄМОДІЯ ПАЛАДІЮ(ІІ) З АЛКІЛЕНДІАМІНТЕТРА(МЕТИЛЕНФОСФОНОВИМИ)
КИСЛОТАМИ
О. М. Козачкова1*, Н. В. Царик1, О. В. Пальчик1, В. І. Пехньо1, В. В. Трачевський2, О. П.
Качоровська3.
1Інститут загальної та неорганічної хімії ім. В.І. Вернадського НАН України,
просп. Акад. Палладіна, 32/34, Київ 03142, Україна;
2ТЦ НАН України, вул. Покровська, буд. 13, Київ 04070, Україна;
Binuclear Pd(II) complexes with pendtmp
exist in solution as several conformers, as evi
denced by the presence in the 31P NMR spectra
of two signals of the phosphorus nuclei of co
ordinated phosphonate groups in a down field
region.
CONCLUSIONS. The results of the study
have shown that in the systems K2[PdCl4]-
edtmp=1:1 and K2[PdCl4]-pendtmp=1:1, com
plexes of equimolar composition [Pd(H4L
1,2)
Cl2]
4-, [Pd(H3L
1,2)Cl]4-, [Pd(H2L
1,2)Cl]5-,
[Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- are formed.
Electron and 31P NMR spectroscopic data in
dicate the bidentate mode of coordination of
edtmp and pendtmp to the central metal ion
via the nitrogen and oxygen atoms of the phos
phonate group in the complex [Pd(H4L
1,2)Cl2]
4-
and a tridentate coordination of ligands by a
nitrogen atom and two oxygen atoms of two
phosphonate groups of one aminodi(methy
lenephosphonate) moiety in the complexes
[Pd(H3L
1,2)Cl]4-, [Pd(H2L
1,2)Cl]5-, [Pd(HL1,2)Cl]6-,
and [Pd(L1,2)Cl]7-. At a metal concentration ra
tio of 2:1 in the case of edtmp, the formation
of sparingly soluble hydrolysis products was
observed in solutions, indicating the impossi
bility of formation of a binuclear complex with
the coordination of the second aminodi(me
thylenephosphonate) moiety of edtmp by ex
cess Pd(II).
In contrast to edtmp, in the system K2[PdCl4]-
pendtmp=2:1, the formation of binuclear
complexes [Pd2(H3L
2)Cl4]
5-, [Pd2(H2L
2)Cl2]
4-,
[Pd2(HL2)Cl2]
5-, and [Pd2(L2)Cl2]
6- was estab
lished. In the complex [Pd2(H3L
2)Cl4]
5-, two
aminodi(methylenephosphonate) moieties
of pendtmp coordinate bidentately to two
Pd(II) ions via the nitrogen and oxygen atoms
of the phosphonate group. In the complex
es [Pd2(H2L
2)Cl2]
4-, [Pd2(HL2)Cl2]
5-, and
57https://ucj.org.ua
O.M. Kozachkova, N.V. Tsaryk, O.V. Palchyk, V.I. Pekhnyo, V.V. Trachevskyi, O.P. Kachorovska UCJ № 6 / Vol. 90
[Pd2(L2)Cl2]
6-, two aminodi(methylphospho
nate) moieties of pendtmp coordinate triden
tately to two Pd(II) ions via a nitrogen atom
and two oxygen atoms of two phosphonate
groups. The possibility of formation of binucle
ar complexes during the interaction of Pd(II)
with pendtmp is realized due to the remote
location of two aminodi(methylphosphonate)
moieties, whereas closely located aminodi(me
thylphosphonate) moieties, as in the case of
edtmp, hinder the coordination of the second
aminodi(methylphosphonate) moiety by ex
cess Pd(II) due to steric hindrances.
This work was done under the state
support according to the theme
“Promising fundamental research
and innovative development of na-
nomaterials and nanotechnologies
for the needs of industry, healthcare
and agriculture”, № state registration
0120U102323, 2020-2024.
ВЗАЄМОДІЯ ПАЛАДІЮ(ІІ) З АЛКІЛЕНДІАМІН
ТЕТРА(МЕТИЛЕНФОСФОНОВИМИ)
КИСЛОТАМИ
О. М. Козачкова1*, Н. В. Царик1,
О. В. Пальчик1, В. І. Пехньо1 ,
В. В. Трачевський2, О. П. Качоровська3.
1Інститут загальної та неорганічної хімії
ім. В.І. Вернадського НАН України,
просп. Акад. Палладіна, 32/34, Київ 03142,
Україна;
2Технічний Центр НАН України, вул. По-
кровська, буд. 13, Київ 04070, Україна;
3Національний технічний університет
України "Київський політехнічний інсти-
тут ім. І. Сікорського",
просп. Берестейський, 37, Київ 03056, Укра-
їна
*е-mail: akozachkova62@gmail.com
Методами рН-потенціометрії, електрон
ної та ЯМР 31Р спектроскопії досліджено
комплексоутворення K2PdCl4 з етилендіамін
тетра(метиленфосфоновою) (edtmp, H8L
1) та
пентаметилендіамінтетра(метиленфосфо
новою) (pendtmp, H8L
2) кислотами в розчи
нах із фізіологічною концентрацією хлорид
іонів (0.15 моль/л KCl). Встановлено, що в
системах Pd(II)-edtmp та Pd(II)-pendtmp
при співвідношенні метал – ліганд=1:1
утворюються комплекси еквімолярно
го складу [Pd(H4L
1,2)Cl2]
4-, [Pd(H3L
1,2)Cl]4-,
[Pd(H2L
1,2)Cl]5-, [Pd(HL1,2)Cl]6- та [Pd(L1,2)Cl]7-,
для яких розраховано константи утворення
та побудовані діаграми розподілу рівноваж
них концентрацій залежно від рН розчину.
Визначено бідентатний спосіб координації
edtmp та pendtmp до центрального іона ме
талу атомами нітрогену та оксигену фос
фонової групи в комплексі [Pd (H4L
1,2)Cl2]
4-
та тридентатним атомом нітрогену та
двома атомами оксигену двох фосфоно
вих груп одного аміноди(метилфосфо
нового) фрагмента в комплексах складу
[Pd(H3L
1,2)Cl]4-, [Pd(H2L
1,2)Cl]5-, [Pd(HL1,2)
Cl]6- та [Pd(L1,2)Cl]7-. При співвідношенні
концентрації Pd(II)-edtmp=2:1 у розчинах
спостерігали утворення малорозчинних
продуктів гідролізу, що свідчить про не
можливість координації другого іона Pd(ІІ)
до другого аміноди(метилфосфонового)
фрагмента ліганду та утворення біядерного
58 ISSN 2708-129X. Укр. хім. журн., 2024
INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. INORGANIC CHEMISTRY
комплексу. На відміну від edtmp в системі
K2[PdCl4]-pendtmp=2:1 встановлено утво
рення біядерних комплексів [Pd2(H3L
2)Cl4]
5-,
[Pd2(H2L
2)Cl2]
4-, [Pd2(HL2)Cl2]
5- та [Pd2(L
2)Cl2]
6-.
В комплексі [Pd2(H3L
2)Cl4]
5- два аміноди(ме
тилфосфонових) фрагменти pendtmp коор
диновані до двох іонів Pd(ІІ) бідентатно
атомами нітрогену та оксигену фосфоно
вої групи, а в комплексах [Pd2(H2L
2)Cl2]
4-,
[Pd2(HL2)Cl2]
5- та [Pd2(L2)Cl2]
6- – триден
татно атомом нітрогену та двома атомами
оксигену двох фосфонових груп.
Ключові слова: амінополіфосфонати,
комплекси паладію, константи утворення.
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Стаття надійшла 20.01.24.
|
| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-667 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:11:47Z |
| publishDate | 2024 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/39/d3a598bb4ab5b39ee16ec6fb929ec939.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-6672026-07-22T08:23:54Z INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. Kozachkova, Oleksandra Tsaryk, Nataliya Pekhnyo, Vasyl Trachevskij, Volodymyr Kocharovska, Olga Palchyk, Oleksii aminopolyphosphonates, palladium complexes, formation constants. The interaction of K2PdCl4 with ethylenediaminetetra(methylenephosphonic) (edtmp, H8L1) and pentamethylenediaminetetra(methylenephosphonic) (pendtmp, H8L2) acids in solutions with physiological chloride ion concentration (0.15 mol L-1KCl) was studied by pH-potentiometry, UV-Vis and NMR spectroscopy. It was established that in the Pd(II)-edtmp and Pd(II)-pendtmp systems at a metal-ligand ratio of 1:1, complexes of equimolar composition [Pd(H4L1,2)Cl2]4-, [Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-, [Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- are formed, for which formation constants were calculated, and distribution diagrams of equilibrium concentrations were constructed as a function of solution pH. A bidentate mode of coordination of edtmp and pendtmp to the central metal ion by the nitrogen and oxygen atoms of the phosphonate group in the [Pd(H4L1,2)Cl2]4- complex and a tridentate mode by a nitrogen atom and two oxygen atoms of two phosphonate groups of one aminodi(methylphosphonate) moiety of ligands in complexes of the compositions [Pd(H3L1,2)Cl]4-, [Pd(H2L1,2)Cl]5-,[Pd(HL1,2)Cl]6-, and [Pd(L1,2)Cl]7- were determined. At the concentration ratio Pd(II)-edtmp=2:1 at pH&gt;3, sparingly soluble hydrolysis products were formed in solutions, indicating the absence of interaction between the non-coordinated aminodi(methylphosphonate) moiety of the ligand and Pd(II) to form a binuclear complex. In contrast to edtmp, the system K2[PdCl4]-pendtmp at a 2:1 ratio exhibited the formation of binuclear complexes [Pd2(H3L2)Cl4]5-, [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6-. In the [Pd2(H3L2)Cl4]5- complex, two aminodi(methylphosphonate) moieties of pendtmp are coordinated to two Pd(II) ions in a bidentate mode by nitrogen and oxygen atoms of the phosphonate group, and in the complexes [Pd2(H2L2)Cl2]4-, [Pd2(HL2)Cl2]5-, and [Pd2(L2)Cl2]6-, they are coordinated in a tridentate mode by a nitrogen atom and two oxygen atoms of two phosphonate groups. V.I.Vernadsky Institute of General and Inorganic Chemistry 2024-07-26 Article Article Inorganic Chemistry Неорганическая химия Неорганічна хімія application/pdf https://ucj.org.ua/index.php/journal/article/view/667 10.33609/2708-129X.90.6.2024.47-58 Ukrainian Chemistry Journal; Vol. 90 No. 6 (2024): Ukrainian Chemistry Journal; 47-58 Украинский химический журнал; ##issue.vol## 90 ##issue.no## 6 (2024): Ukrainian Chemistry Journal; 47-58 Український хімічний журнал; Том 90 № 6 (2024): Ukrainian Chemistry Journal; 47-58 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/667/332 Copyright (c) 2024 Oleksandra Kozachkova, Nataliya Tsaryk, Vasyl Pekhnyo, Volodymyr Trachevskij, Olga Kocharovska, Oleksii Palchyk https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Kozachkova, Oleksandra Tsaryk, Nataliya Pekhnyo, Vasyl Trachevskij, Volodymyr Kocharovska, Olga Palchyk, Oleksii INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. |
| title | INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. |
| title_full | INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. |
| title_fullStr | INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. |
| title_full_unstemmed | INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. |
| title_short | INTERACTION OF PALLADIUM(II) WITH ALKYLENEDIAMINETETRA(METHYLENEPHOSPHONIC) ACIDS. |
| title_sort | interaction of palladium(ii) with alkylenediaminetetra(methylenephosphonic) acids. |
| topic_facet | aminopolyphosphonates palladium complexes formation constants. |
| url | https://ucj.org.ua/index.php/journal/article/view/667 |
| work_keys_str_mv | AT kozachkovaoleksandra interactionofpalladiumiiwithalkylenediaminetetramethylenephosphonicacids AT tsaryknataliya interactionofpalladiumiiwithalkylenediaminetetramethylenephosphonicacids AT pekhnyovasyl interactionofpalladiumiiwithalkylenediaminetetramethylenephosphonicacids AT trachevskijvolodymyr interactionofpalladiumiiwithalkylenediaminetetramethylenephosphonicacids AT kocharovskaolga interactionofpalladiumiiwithalkylenediaminetetramethylenephosphonicacids AT palchykoleksii interactionofpalladiumiiwithalkylenediaminetetramethylenephosphonicacids |