ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS
In the present study, the crystal structures of non-chelating EDTA molecules and their non-chelation salts in a zwitterionic state, along with the EDTA-chelates of alkali and alkaline earth metals, were searched and overviewed. 25 non-chelating molecules of EDTA, and zwitterions of ethylenediammoniu...
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Ukrainian Chemistry Journal| _version_ | 1871465868987203584 |
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| author | Noguchi, Daisuke |
| author_facet | Noguchi, Daisuke |
| author_institution_txt_mv | [
{
"author": "Daisuke Noguchi",
"institution": "Division of Education and Research Support, Graduate School of Engineering, Nagasaki University, 1–14 Bunkyo-machi, 8528521Nagasaki, Japan"
}
] |
| author_sort | Noguchi, Daisuke |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:50Z |
| description | In the present study, the crystal structures of non-chelating EDTA molecules and their non-chelation salts in a zwitterionic state, along with the EDTA-chelates of alkali and alkaline earth metals, were searched and overviewed. 25 non-chelating molecules of EDTA, and zwitterions of ethylenediammonium-diacetate diacetic acid HOOC-CH2-(-OOC-CH2-)NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH and their salts (ethylenediammonium-tetraacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2, ethylenediammonium-acetate triacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH, and ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)2 with counterions, as well as 17 types of EDTA-chelates of alkali metal ions (Li+, Na+, K+, Rb+) and alkaline earth metal ions (Mg2+, Ca2+, Sr2+, Ba2+) were analyzed using data from the Cambridge Crystallographic Data Center (CCDC). Each intramolecular contact distance between nitrogen and oxygen atoms (NH+···O) has been examined and found to be around 2.7 Å. Investigation on the distribution of the intramolecular NH+··· NH+-distances of EDTA and non-chelated salts thereof also revealed that bulky counterion and certain crystal solvent molecules correspond to change in crystal packing, and that they influenced the conformers of EDTA molecules among gauche form to anti form. In the existing crystalline EDTA-chelates of alkali metals as well as alkaline earth metals, various coordination numbers (CN) and the denticity (к) of EDTA anions are displayed; CN 5 to 9, and tri- and hexadentate fashions. Intramolecular contact N···O and N···N distances correspond to the metal ion radii except for the case of Sr-EDTA chelate, probably due to differences of crystal packings in addition to the number of counterions and crystal solvent molecules. The existing data on crystalline EDTA and its salts have been gathered herein, which contributes to a further understanding and exploring applications hereafter. |
| doi_str_mv | 10.33609/2708-129X.88.10.2022.55-69 |
| first_indexed | 2025-09-24T17:43:47Z |
| format | Article |
| fulltext |
55
UDK 548.31+541.49: 546.41+546.42+546.43+546.46+546.32+546.33+546.34+546.35 - 54-386 doi: 10.33609/2708-129X.88.10.2022.55-69
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-
CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC
ACID AND ITS SALTS WITH ALKALI AND ALKALINE
EARTH METALS
Daisuke Noguchi
Division of Education and Research Support, Graduate School of Engineering, Nagasaki University,
1–14 Bunkyo-machi, 8528521Nagasaki, Japan.
Email: a.chemist.noguchi.d@gmail.com
In the present study, the crystal structures of non-chelating EDTA molecules and their non-chela-
tion salts in a zwitterionic state, along with the EDTA-chelates of alkali and alkaline earth metals,
were searched and overviewed. 25 non-chelating molecules of EDTA, and zwitterions of ethylene-
diammonium-diacetate diacetic acid HOOC-CH2-(-OOC-CH2-)NH+-CH2-CH2-NH+(-CH2-COO-)-
CH2-COOH and their salts (ethylenediammonium-tetraacetic acid (HOOC-CH2-)2NH+-CH2-CH2-
NH+(-CH2-COOH)2, ethylenediammonium-acetate triacetic acid (HOOC-CH2-)2NH+-CH2-CH2-
NH+(-CH2-COO-)-CH2-COOH, and ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-
CH2-NH+(-CH2-COO-)2 with counterions, as well as 17 types of EDTA-chelates of alkali metal ions
(Li+, Na+, K+, Rb+) and alkaline earth metal ions (Mg2+, Ca2+, Sr2+, Ba2+) were analyzed using data from
the Cambridge Crystallographic Data Center (CCDC). Each intramolecular contact distance between
nitrogen and oxygen atoms (NH+···O) has been examined and found to be around 2.7 Å. Investigation
on the distribution of the intramolecular NH+··· NH+-distances of EDTA and non-chelated salts there-
of also revealed that bulky counterion and certain crystal solvent molecules correspond to change in
crystal packing, and that they influenced the conformers of EDTA molecules among gauche form to
anti form. In the existing crystalline EDTA-chelates of alkali metals as well as alkaline earth metals,
various coordination numbers (CN) and the denticity (к) of EDTA anions are displayed; CN 5 to 9,
and tri- and hexadentate fashions. Intramolecular contact N···O and N···N distances correspond to the
metal ion radii except for the case of Sr-EDTA chelate, probably due to differences of crystal packings
in addition to the number of counterions and crystal solvent molecules. The existing data on crystal-
line EDTA and its salts have been gathered herein, which contributes to a further understanding and
exploring applications hereafter.
Keywords: CCDC, EDTA, Hydrogen bonding, X-ray crystallography.
INTRODUCTION. Ethylenediaminetetra
acetic acid (EDTA; abbreviated as H4Y) is
widely known as a common chelator and well
characterized as metal-chelates. Not just EDTA-
chelates but EDTA itself and dozens of its
existing non-chelating conformational salts of
inorganic acids, bases, alkali metals, and al-
kaline earth metals have been reported with
crystal data so far. However, the structural sys-
tematization of other remaining EDTA species
unlike the EDTA-chelates of heavy metals has
rarely been documented, despite a recently
56 ISSN 2708-129X. Укр. хім. журн., 2022
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS
OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALSINORGANIC CHEMISTRY
found function such as their unusual lumi-
nescence activity. Ethylenediaminetetraacetic
acid (EDTA; Fig. 1), a typical chelating agent
that forms complexes with various metal ions,
has been given attention for molecular bio
logy, chemical industry, and materials engi-
neering (e.g., Blaurock-Busch 2016) [1]. Thus
far, the crystalline structural studies of EDTA
have been focused on chelate complexes with
various metal ions (Lee 1972, Porai-Koshits
et al. 1974, Nuttall & Stalker 1977, Stezowski
& Hoard 1984, Davidovich 2005, Stavila et al.
2006, Wang et al. 2010, Noguchi 2022a) [2–9].
The crystal structures of non-chelating EDTA
molecules have also been investigated in
preceding studies; however, they are not well
summarized compared to the large variety of
existing heavy metal chelates of EDTA. There-
fore, this study focused on a structural point of
view, and conformations, including potential
hydrogen-bonded contact nitrogen and oxy-
gen atomic distances were overviewed utilizing
crystallographic data deposited in the Cam-
bridge Crystallographic Data Centre (CCDC).
Fig. 1.Zwitterionic EDTA molecule (=H4Y).
INVESTIGATION AND DISCUSSION OF
THE RESULTS. Based on the cif files available
in the Cambridge Structural Database (Groom
et al. 2016) [10], information on non-chelat-
ing zwitterionic EDTA molecules and their
salts were summarized in Table 1 and shown in
Fig. 2.25 kinds of crystalline compounds were
hit by searching; however, three cif files of CCDC
Nos. 1148821, 1148825, and 1148828could not
be opened by crystal structure viewing software;
Mercury 1.4.2. (build 2); i.e., crystal structure
visualisation, exploration and analysis free-soft-
ware. By checking the 22kinds’ cif files of the
other by Mercury freeware, the distribution of
intramolecular NH+···O distances of non-chelate
conformational zwitterions of EDTA and salts
thereof was demonstrated in Table 2 and Fig. 3.
itself and dozens of its existing non-chelating conformational salts of inorganic acids, bases, alkali
metals, and alkaline earth metals have been reported with crystal data so far. However, the structural
systematization of other remaining EDTA species unlike the EDTA-chelates of heavy metals has
rarely been documented, despite a recently found function such as their unusual luminescence activity.
Ethylenediaminetetraacetic acid (EDTA; Fig. 1), a typical chelating agent that forms complexes with
various metal ions, has been given attention for molecular biology, chemical industry, and materials
engineering (e.g., Blaurock-Busch 2016) [1]. Thus far, the crystalline structural studies of EDTA have
been focused on chelate complexes with various metal ions (Lee 1972, Porai-Koshits et al. 1974,
Nuttall & Stalker 1977, Stezowski & Hoard 1984, Davidovich 2005, Stavila et al. 2006, Wang et al.
2010, Noguchi 2022a) [2–9]. The crystal structures of non-chelating EDTA molecules have also been
investigated in preceding studies; however, they are not well summarized compared to the large
variety of existing heavy metal chelates of EDTA. Therefore, this study focused on a structural point
of view, and conformations, including potential hydrogen-bonded contact nitrogen and oxygen
atomic distances were overviewed utilizing crystallographic data deposited in the Cambridge
Crystallographic Data Centre (CCDC).
Fig. 1.Zwitterionic EDTA molecule (=H4Y).
INVESTIGATION AND DISCUSSION OF THE RESULTS. Based on the cif files available in the
Cambridge Structural Database (Groom et al. 2016) [10], information on non-chelating zwitterionic
EDTA molecules and their salts were summarized in Table 1 and shown in Fig. 2.25 kinds of
crystalline compounds were hit by searching; however, three cif files of CCDC Nos. 1148821,
1148825, and 1148828could not be opened by crystal structure viewing software; Mercury 1.4.2.
(build 2); i.e., crystal structure visualisation, exploration and analysis free-software. By checking the
22kinds’ cif files of the other by Mercury freeware, the distribution of intramolecular NH+···O
distances of non-chelate conformational zwitterions of EDTA and salts thereof was demonstrated in
Table 2 and Fig. 3.
itself and dozens of its existing non-chelating conformational salts of inorganic acids, bases, alkali
metals, and alkaline earth metals have been reported with crystal data so far. However, the structural
systematization of other remaining EDTA species unlike the EDTA-chelates of heavy metals has
rarely been documented, despite a recently found function such as their unusual luminescence activity.
Ethylenediaminetetraacetic acid (EDTA; Fig. 1), a typical chelating agent that forms complexes with
various metal ions, has been given attention for molecular biology, chemical industry, and materials
engineering (e.g., Blaurock-Busch 2016) [1]. Thus far, the crystalline structural studies of EDTA have
been focused on chelate complexes with various metal ions (Lee 1972, Porai-Koshits et al. 1974,
Nuttall & Stalker 1977, Stezowski & Hoard 1984, Davidovich 2005, Stavila et al. 2006, Wang et al.
2010, Noguchi 2022a) [2–9]. The crystal structures of non-chelating EDTA molecules have also been
investigated in preceding studies; however, they are not well summarized compared to the large
variety of existing heavy metal chelates of EDTA. Therefore, this study focused on a structural point
of view, and conformations, including potential hydrogen-bonded contact nitrogen and oxygen
atomic distances were overviewed utilizing crystallographic data deposited in the Cambridge
Crystallographic Data Centre (CCDC).
Fig. 1.Zwitterionic EDTA molecule (=H4Y).
INVESTIGATION AND DISCUSSION OF THE RESULTS. Based on the cif files available in the
Cambridge Structural Database (Groom et al. 2016) [10], information on non-chelating zwitterionic
EDTA molecules and their salts were summarized in Table 1 and shown in Fig. 2.25 kinds of
crystalline compounds were hit by searching; however, three cif files of CCDC Nos. 1148821,
1148825, and 1148828could not be opened by crystal structure viewing software; Mercury 1.4.2.
(build 2); i.e., crystal structure visualisation, exploration and analysis free-software. By checking the
22kinds’ cif files of the other by Mercury freeware, the distribution of intramolecular NH+···O
distances of non-chelate conformational zwitterions of EDTA and salts thereof was demonstrated in
Table 2 and Fig. 3.
(a) (b) (c)
Fig. 2. Non-chelate conformational EDTA zwitterions in salts thereof; (a) ethylenediammonium-
tetraacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2 (=H6Y
2+), (b) ethylenediammo-
nium-acetate triacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH (=H5Y
+),
(c) ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)2 (=H2Y
2-).
57https://ucj.org.ua
Daisuke Noguchi UCJ № 10 / Vol. 88
Table 1
Non-chelating zwitterionic EDTA molecules and their salts with reported crystal structures (type,
entry number, chemical formula, CCDC number, and references).
Type Entry
No. Chemical Formula CCDC No. Ref.
H2EDTA2+ 1* EDTA·2HCl·3H2O 657759 Kaluderović et al. 2007 [11]
(H6Y
2+) 2* EDTA·2HCl·3H2O 1163542 Mistryukov et al. 1987 [12]
3 EDTA·H2SO4·H2O 1300053 Shkol'nikova et al. 1993 [13]
HEDTA+
(H5Y
+) 4 EDTA·HBr·H2O 1283049 Shkol'nikova et al. 1989 [14]
EDTA 5 EDTA·0.39H2O 1101398 Ladd et al. 1974 [15]
(H4Y) 6* EDTA 1148825 Lu & Shao 1962 [16]
7* EDTA 1148826 Cotrait 1972 [17]
8* EDTA 1148827 Ladd & Povey 1973 [18]
9* EDTA 1148828 Wang et al. 2003 [19]
10 (H3O)Na₂[Ni(EDTA-2H)]
PW₁₂O₄₀·EDTA·5H₂O 1433251 Xiao et al. 2016 [20]
[EDTA-2H]2- 11 [Mn(H2O)6][EDTA-2H] 285809 Ma & Niu 2003 [21]
(H2Y
2-) 12 N2H5[EDTA-2H] 656243
Ragul et al. 2015 [22]
13 (N2H5)₂[EDTA-2H] 656246
14 Sr2 [EDTA-2H]Cl2·5H2O 686018
Polyakova et al. 2009 [23]
15 Sr2 [EDTA-2H](HCO3)2·4H2O 686020
16 {HC3N₃(NH₂)₃}₂[EDTA-
2H]·2H₂O 741062 Vella-Zarb et al. 2014 [24]
17* K2 [EDTA-2H]·2H2O 838146 Krawczyk & Lis 2011 [25]
18** Na2 [EDTA-2H]·2H2O 1020814 Fronczek 2014 [26]
19 (NH₄)(N2H5)[EDTA-
2H]·NH₃·2H₂O 1033967 Sivasankar & Sonia 2015 [27]
20 [Mg(H2O)6][EDTA-2H] 1103464 Julian et al. 1973 [28]
21 Rb2 [EDTA-2H]·2H2O 1147983 Cotrait 1970 [29]
22* K2 [EDTA-2H]·2H2O 1148821 Cotrait 1969 [30]
23 Ca[EDTA-2H]·2H2O 1166578 Zabel et al. 2006 [31]
24** Na2 [EDTA-2H]·2H2O 1171161 Font-Bardia et al. 1993 [32]
25 Na2[Te(OH)6][EDTA-2H]·2H2O 1309261 Cisarova et al. 1995 [33]
26* K2 [EDTA-2H]·2H2O 1968403 Meier & Massa 2019 [34]
27** Na₂[EDTA-2H]·2H₂O 2051489 Zheng et al. 2021 [1]
58 ISSN 2708-129X. Укр. хім. журн., 2022
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS
OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALSINORGANIC CHEMISTRY
Fig. 3. Intramolecular hydrogen-bonded NH+⋅⋅⋅O distances of non-chelating zwitterionic EDTA mo
lecules and their salts vs. sample counts of each hydrogen bonds.
(a) (b) (c)
Fig. 2. Non-chelate conformational EDTA zwitterions in salts thereof; (a) ethylenediammonium-tetraacetic
acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2 (=H6Y2+), (b) ethylenediammonium-acetate triacetic
acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH (=H5Y+), (c)
ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)2 (=H2Y2-).
Fig. 3. Intramolecular hydrogen-bonded NH+O distances of non-chelating zwitterionic EDTA molecules and
their salts vs. sample counts of each hydrogen bonds.
Table 1
Non-chelating zwitterionic EDTA molecules and their salts with reported crystal structures (type,
entry number, chemical formula, CCDC number, and references).
Type
Entry
No.
Chemical Formula
CCDC
No.
Ref.
H2EDTA2+ 1* EDTA·2HCl·3H2O 657759 Kaluderović et al. 2007 [11]
(H6Y2+) 2* EDTA·2HCl·3H2O 1163542 Mistryukov et al. 1987 [12]
3 EDTA·H2SO4·H2O 1300053 Shkol'nikova et al. 1993 [13]
HEDTA+
(H5Y+)
4 EDTA·HBr·H2O 1283049 Shkol'nikova et al. 1989 [14]
EDTA 5 EDTA·0.39H2O 1101398 Ladd et al. 1974 [15]
(H4Y) 6* EDTA 1148825 Lu & Shao 1962 [16]
7* EDTA 1148826 Cotrait 1972 [17]
8* EDTA 1148827 Ladd & Povey 1973 [18]
Sa
m
pl
e
co
un
ts
Distances of intramolecular NO / Å
Intramolecular distances between one am-
monium-nitrogen atom and another (NH+···
NH+) within everyzwitterionic EDTA mole-
cule including its salt werealso surveyed by
checking cif files and shown in Table 2 (right)
and Fig. 4.
Fig. 4. Intramolecular NH+⋅⋅⋅ NH+distances of non-chelating zwitterionic EDTA molecules and their
salts vs. sample counts.
Fig. 4. Intramolecular NH+ NH+distances of non-chelating zwitterionic EDTA molecules and their salts vs.
sample counts.
Table 2
Intramolecular hydrogen-bonded ammonium-nitrogen and oxygen atomic (NH+O), as well as one
ammonium-nitrogen and other ammonium-nitrogen atomic (NH+ NH+) distances of non-chelating
conformational EDTA zwitterions according to data available in CCDC.
Entry NH+O distances / Å NH+ NH+ distances / Å CCDC No.
1 2.684 2.689 2.822 2.684 2.689 2.822 3.163 657759
2 2.671 2.689 2.699 2.716
3.935 1163542
3 2.705 2.737 2.705 2.737
3.839 1300053
4 2.647 2.648 2.700 2.718
3.809 1283049
5 2.679 2.680 2.796 2.679 2.680 2.796 3.121 1101398
6 No data 1148825
7 2.682 2.748 2.788 2.682 2.748 2.788 3.195 1148826
8 2.675 2.751 2.780 2.675 2.751 2.780 3.199 1148827
9 No data 1148828
10 2.664 2.701 2.813 2.860
2.783 1433251
11 2.661 2.698 2.661 2.698
3.795 285809
12 2.699 2.710 2.699 2.710
3.840 656243
13 2.696 2.705 2.696 2.705
3.838 656246
Sa
m
pl
e
co
un
ts
Distances of intramolecular NN / Å
59https://ucj.org.ua
Daisuke Noguchi UCJ № 10 / Vol. 88
Table 2
Intramolecular hydrogen-bonded ammonium-nitrogen and oxygen atomic (NH+⋅⋅⋅O), as well as one
ammonium-nitrogen and other ammonium-nitrogen atomic (NH+⋅⋅⋅ NH+) distances of non-chelating
conformational EDTA zwitterions according to data available in CCDC.
Entry NH+⋅⋅⋅O distances / Å NH+⋅⋅⋅ NH+ distances / Å CCDC No.
1 2.684 2.689 2.822 2.684 2.689 2.822 3.163 657759
2 2.671 2.689 2.699 2.716 3.935 1163542
3 2.705 2.737 2.705 2.737 3.839 1300053
4 2.647 2.648 2.700 2.718 3.809 1283049
5 2.679 2.680 2.796 2.679 2.680 2.796 3.121 1101398
6 No data 1148825
7 2.682 2.748 2.788 2.682 2.748 2.788 3.195 1148826
8 2.675 2.751 2.780 2.675 2.751 2.780 3.199 1148827
9 No data 1148828
10 2.664 2.701 2.813 2.860 2.783 1433251
11 2.661 2.698 2.661 2.698 3.795 285809
12 2.699 2.710 2.699 2.710 3.840 656243
13 2.696 2.705 2.696 2.705 3.838 656246
14 2.757 2.780 3.837 686018
15 2.692 2.755 2.692 2.755 3.803 686020
16 2.698 2.723 2.698 2.723 3.820 741062
17 2.675 2.687 2.700 2.742 2.803 3.171 838146
18 2.739 2.751 2.739 2.751 3.830 1020814
19 2.674 2.727 2.762 2.728 2.780 2.800 3.192 1033967
20 2.660 2.708 2.660 2.708 3.803 1103464
21 2.592 2.612 2.632 2.633 3.772 1147983
22 No data 1148821
23 2.654 2.713 2.717 2.735 2.776 2.853 3.154 1166578
24 2.733 2.733 2.733 2.733 3.818 1171161
25 2.627 2.650 2.709 2.769 3.809 1309261
26 2.661 2.716 2.726 2.745 2.779 2.806 3.171 1968403
27 2.737 2.758 2.737 2.758 3.828 2051489
60 ISSN 2708-129X. Укр. хім. журн., 2022
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS
OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALSINORGANIC CHEMISTRY
In terms of NH+··· NH+ distances, there seem
to be two groups; i.e., below 3.3Å and above
3.7 Å. EDTA molecules have gauche-confor-
mations within ethylenediamine moieties if
NH+··· NH+ distances are below 3.3 Å, whereas
in the cases of NH+··· NH+ distances distribut-
ing around3.8Å, they have anti-conformations
(Fig. 5).
Fig. 5. Anti-conformer (left) and gauche-con-
former (right) within an ethylenediamine moiety of
EDTA (acetic acid groups are omitted for clarity).
If there are no other species neighboring the
EDTA itself, anti-forms are more stable than
gauche-forms due to the intra/inter-molecu-
lar repulsive forces. However, in certain cases,
crystal packings stabilize gauche-EDTA rath-
er than anti-EDTA, and the effect allows the
existence of a small number of gauche-forms.
Amongst the intramolecular NH+··· NH+ dis-
tances, a noticeably short distance (2.783 Å)
with a torsion angle of 47.82° of φN-C-C-N (in-
deed, typical angle is 60° for the gauche form) is
characteristic of the EDTA molecule of CCDC
No. 1433251drawn in Fig. 6. In this case, ex-
cept for the EDTA molecule itself, additional
species such as “(H3O)Na2[Ni(EDTA-2H)]
PW12O40·5H2O”, including phosphododeca-
tungstate [PW12O40]
3-, known as heteropoly-
acid salts having Keggin structure, is much larg-
er than any other cases. Accordingly, it seems
that the crystal packing by species except for
EDTA molecules could strongly change intra-
molecular interactions in crystals.
14 2.757 2.780
3.837 686018
15 2.692 2.755 2.692 2.755
3.803 686020
16 2.698 2.723 2.698 2.723
3.820 741062
17 2.675 2.687 2.700 2.742 2.803
3.171 838146
18 2.739 2.751 2.739 2.751
3.830 1020814
19 2.674 2.727 2.762 2.728 2.780 2.800 3.192 1033967
20 2.660 2.708 2.660 2.708
3.803 1103464
21 2.592 2.612 2.632 2.633
3.772 1147983
22 No data 1148821
23 2.654 2.713 2.717 2.735 2.776 2.853 3.154 1166578
24 2.733 2.733 2.733 2.733
3.818 1171161
25 2.627 2.650 2.709 2.769
3.809 1309261
26 2.661 2.716 2.726 2.745 2.779 2.806 3.171 1968403
27 2.737 2.758 2.737 2.758
3.828 2051489
In terms of NH+··· NH+ distances, there seem to be two groups; i.e., below 3.3Å and above 3.7 Å.
EDTA molecules have gauche-conformations within ethylenediamine moieties if NH+··· NH+
distances are below 3.3 Å, whereas in the cases of NH+··· NH+ distances distributing around3.8Å,
they have anti-conformations (Fig. 5).
Fig. 5. Anti-conformer (left) and gauche-conformer (right) within an ethylenediamine moiety of EDTA (acetic
acid groups are omitted for clarity).
If there are no other species neighboring the EDTA itself, anti-forms are more stable than
gauche-forms due to the intra/inter-molecular repulsive forces. However, in certain cases, crystal
packings stabilize gauche-EDTA rather than anti-EDTA, and the effect allows the existence of a small
number of gauche-forms. Amongst the intramolecular NH+··· NH+ distances, a noticeably short
distance (2.783 Å) with a torsion angle of 47.82° of φN-C-C-N (indeed, typical angle is 60° for the
gauche form) is characteristic of the EDTA molecule of CCDC No. 1433251drawn in Fig. 6. In this
case, except for the EDTA molecule itself, additional species such as
“(H3O)Na2[Ni(EDTA-2H)]PW12O40·5H2O”, including phosphododecatungstate [PW12O40]3-, known
Fig. 6. Gauche-conformer of EDTA (torsion angle 47.82°) in (H3O)Na2[Ni(EDTA-2H)]PW12O40·
EDTA·5H2O by ellipsoids of carbon (grey), nitrogen (blue), oxygen (red) (50% probability, respectively)
with hydrogen (white sphere) (Xiao et al. 2016) [20].
as heteropolyacid salts having Keggin structure, is much larger than any other cases. Accordingly, it
seems that the crystal packing by species except for EDTA molecules could strongly change
intramolecular interactions in crystals.
Fig. 6. Gauche-conformer of EDTA (torsion angle 47.82°) in (H3O)Na2[Ni(EDTA-2H)]PW12O40·EDTA·5H2O
by ellipsoids of carbon (grey), nitrogen (blue), oxygen (red) (50% probability, respectively) with hydrogen
(white sphere) (Xiao et al. 2016) [20].
It would be significant to analyze the dependence of the change in the intramolecular distances of
N···O and N···N atoms on the value of the crystal radius in a series of alkali metals as well as alkaline
earth metals; herein, nitrogen atom is coordinated to a metal ion. In order to compare with the cases of
non-chelate EDTA and salts thereof, crystal data of EDTA-chelates of alkali metals besides alkaline
earth metals have been also searched for and displayed in Table 3. The intramolecular distances of
nitrogen and oxygen atoms (N···O)were summarized in Table 4.
Table 3
Type, Entry No., chemical formula, CCDC numbers of, and references to EDTA-chelates of alkali
metals as well as alkaline earth metals with reported crystal structures.
Type
Entry
No.
Chemical Formula
CCDC
No.
Ref.
[EDTA-3H]3-
(HY3-)
28 [K3(EDTA-3H)]·2H2O 838147 Krawczyk & Lis 2011 [25]
[EDTA-4H]4-
(Y4-)
29
[Ni(Phen)3][Ba(EDTA
-4H)(H2O)2]·12H2O
Phen = 1,10-phenanthroline
196670 Sadikov et al. 2002 [38]
61https://ucj.org.ua
Daisuke Noguchi UCJ № 10 / Vol. 88
It would be significant to analyze the de-
pendence of the change in the intramolecu-
lar distances of N···O and N···N atoms on the
value of the crystal radius in a series of alkali
metals as well as alkaline earth metals; herein,
nitrogen atom is coordinated to a metal ion. In
order to compare with the cases of non-chelate
EDTA and salts thereof, crystal data of EDTA-
chelates of alkali metals besides alkaline earth
metals have been also searched for and dis-
played in Table 3. The intramolecular distan
ces of nitrogen and oxygen atoms (N···O)were
summarized in Table 4.
Table 3
Type, Entry No., chemical formula, CCDC numbers of, and references to EDTA-chelates of alkali
metals as well as alkaline earth metals with reported crystal structures.
Type Entry
No. Chemical Formula CCDC No. Ref.
[EDTA-3H]3-
(HY3-) 28 [K3(EDTA-3H)]·2H2O 838147 Krawczyk & Lis 2011 [25]
[EDTA-4H]4-
(Y4-) 29
[Ni(Phen)3][Ba(EDTA
-4H)(H2O)2]·12H2O
Phen = 1,10-phenanthroline
196670 Sadikov et al. 2002 [38]
30 [Ni(Phen)3][Ca(EDTA
-4H)(H2O) 2]·10.5H2O
196671 Antsyshkina et al. 2002 [39]
31 [Sr2 (EDTA-4H)]·5H2O 686019 Polyakova et al. 2009 [23]
32 [Ba2 (EDTA-4H)] 765935
Chen et al. 2010 [40]
33* [Ba2 (EDTA-4H)]·2.5H2O 765936
34 [Li4(EDTA-4H)]·2H2O 809471 Cheng et al. 2013 [41]
35 [K4(EDTA-4H)]·3.92H2O 838148 Krawczyk & Lis 2011 [25]
36* [Ba2 (EDTA-4H)]·2.5H2O 1104933 Shao 1979 [42]
37 [Ca2 (EDTA-4H)]·7H2O 1148812 Barnett et al. 1979 [43]
38 [Co(NH3)6][Na(EDTA-
4H)]·3.5H2O
1148813 Schlemper 1977 [44]
39 [Na4(EDTA-4H)]·5H2O 1171162 Font-Bardia et al. 1993 [32]
40 [Mg(H2O)6][Mg(H2O)(EDTA-
4H)]·2H2O
1211677 Passer et al. 1977 [45]
41 1211678 Pozhidaev et al. 1974a [46]
42 Na2 [Mg(EDTA-4H)(H2O)]·3H2O 1211717 Pozhidaev et al. 1974b [47]
43 Na2 [Mg(EDTA-4H)(H2O)]·5H2O 1216509 Stezowski et al. 1973 [48]
44 Sr[Ca(EDTA-4H)]·5H2O 1286595 Arriortua et al. 1992 [49]
62 ISSN 2708-129X. Укр. хім. журн., 2022
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS
OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALSINORGANIC CHEMISTRY
Table 4
Intramolecular distances of nitrogen and oxygen atoms (N⋅⋅⋅O) and one nitrogen and another nitrogen
atom (N⋅⋅⋅N) of chelating alkali metal- and alkaline earth metals-EDTA complexes according to cif
files available in CCDC.
Entry N⋅⋅⋅Odistances / Å N⋅⋅⋅Ndistances / Å CCDC No.
28 2.636 2.646 2.838 2.841 2.951 838147
29 2.725 2.742 2.747 2.747 3.054 196670
30 2.694 2.723 2.769 2.789 2.978 196671
31 2.706 2.731 2.745 2.762 3.019 686019
32 2.781 2.826 2.781 2.826 3.801 765935
33 2.711 2.749 2.750 2.767 2.998 765936
34 2.705 2.762 2.705 2.762 3.788 809471
35
2.777 2.795 2.826 2.828 3.040
838148
2.784 2.791 2.780 2.862 3.078
36 2.638 2.965 2.655 2.826 2.961 1104933
37 2.722 2.794 2.813 2.836 2.951 1148812
38 2.766 2.815 2.766 2.815 3.062 1148813
39 2.697 2.738 2.750 2.865 2.923 1171162
40 2.687 2.767 2.687 2.767 2.888 1211677
41 2.692 2.754 2.692 2.754 2.879 1211678
42 No data 1211717
43 2.675 2.679 2.675 2.679 2.906 1216509
44 2.684 2.698 2.706 2.711 2.953 1286595
The distribution of distances of intramole
cular nitrogen and oxygen atoms (N···O) and
nitrogen-nitrogen atoms (N···N) of these che-
lates listed in Table 4 is shown in Fig 7 and Fig. 8,
except for Na2[Mg(EDTA-4H)(H2O)]·3H2O
(Pozhidaev et al. 1974b) [47] because ofbeing
unavailable for checking 3D structure by the
cif file (CCDC No. 1211717).
Averaged intramolecular N···O distanc-
es in EDTA-chelates of every metal are as
follow: 2.734 Åof Li-Y([Li4(EDTA-4H)]·
2H2O, CCDC No. 809471), 2.777 Å of Na-Y
([Co(NH3)6][Na(EDTA-4H)]·3.5H2O, 1148813;
[Na4(EDTA-4H)]·5H2O, 1171162), 2.805 Å
of K-Y([K4(EDTA-4H)]·3.92H2O, 838148),
2.709 Å of Mg-Y ([Mg(H2O)6][Mg(H2O)(ED-
TA-4H)]·2H2O, 1211677; 1211678; Na2[Mg(ED-
TA-4H)(H2O)]·5H2O, 1216509), 2.745Å of Ca-Y
([Ni(Phen)3][Ca(EDTA-4H)(H2O)2]·10.5H2O,
196671; [Ca2(EDTA-4H)]·7H2O, 1148812; Sr[-
Ca(EDTA-4H)]·5H2O, 1286595), 2.736 Å of
Sr-Y ([Sr2(EDTA-4H)]·5H2O, 686019), and
2.765 Å of Ba-Y ([Ni(Phen)3][Ba(EDTA-4H)
(H2O)2]·12H2O, 196670; [Ba2(EDTA-4H)],
63https://ucj.org.ua
Daisuke Noguchi UCJ № 10 / Vol. 88
Fig. 7. Intramolecular N⋅⋅⋅O distances of EDTA-chelates of alkali metals as well as alkaline earth metals
vs. sample counts.
Fig. 8. Intramolecular N⋅⋅⋅N distances of EDTA-chelates of alkali metals and alkaline earth metals vs.
sample counts.
43 2.675 2.679 2.675 2.679 2.906 1216509
44 2.684 2.698 2.706 2.711 2.953 1286595
The distribution of distances of intramolecular nitrogen and oxygen atoms (N···O) and
nitrogen-nitrogen atoms (N···N) of these chelates listed in Table 4 is shown in Fig 7 and Fig. 8, except
for Na2[Mg(EDTA-4H)(H2O)]·3H2O (Pozhidaev et al. 1974b) [47] because ofbeing unavailable for
checking 3D structure by the cif file (CCDC No. 1211717).
Fig. 7. Intramolecular NO distances of EDTA-chelates of alkali metals as well as alkaline earth metals vs.
sample counts.
Sa
m
pl
e
co
un
ts
Distances between intramolecular NO / Å
Fig. 8. Intramolecular NN distances of EDTA-chelates of alkali metals and alkaline earth metals vs. sample
counts.
Averaged intramolecular N···O distances in EDTA-chelates of every metal are as follow: 2.734
Åof Li-Y([Li4(EDTA-4H)]·2H2O, CCDC No. 809471), 2.777 Å of Na-Y
([Co(NH3)6][Na(EDTA-4H)]·3.5H2O, 1148813; [Na4(EDTA-4H)]·5H2O, 1171162), 2.805 Å of
K-Y([K4(EDTA-4H)]·3.92H2O, 838148), 2.709 Å of Mg-Y
([Mg(H2O)6][Mg(H2O)(EDTA-4H)]·2H2O, 1211677; 1211678; Na2[Mg(EDTA-4H)(H2O)]·5H2O,
1216509), 2.745Å of Ca-Y ([Ni(Phen)3][Ca(EDTA-4H)(H2O)2]·10.5H2O, 196671;
[Ca2(EDTA-4H)]·7H2O, 1148812; Sr[Ca(EDTA-4H)]·5H2O, 1286595), 2.736 Å of Sr-Y
([Sr2(EDTA-4H)]·5H2O, 686019), and 2.765 Å of Ba-Y
([Ni(Phen)3][Ba(EDTA-4H)(H2O)2]·12H2O, 196670; [Ba2(EDTA-4H)], 765935;
[Ba2(EDTA-4H)]·2.5H2O, 765936;; 1104933).On the other hand, averaged intramolecular N···N
distances in the same EDTA-chelates are as follow: 3.788 Å of Li-Y, 2.993 Å of Na-Y, 3.059 Å of K-Y,
2.891 Å of Mg-Y, 2.961 Åof Ca-Y, 3.019 Å of Sr-Y, 3.204 Å of Ba-Y. These averaged intramolecular
N···O distances in EDTA anions (=Y4-) in addition to coordination numbers (CN), denticity (), and
the crystal radii of metal ions by Shannon (1976) [50] are displayed in Table 5.It seems that only
Sr-EDTA chelates are out of the sequence of each metalion radius for having a short N···O distance.
Similarly, Polynova et al. (2009) noted that the Sr-N bonds in the Sr-Y complex (CCDC No. 686019)
are somewhat shorter than those of strontium nitrilotriacetate; i.e., Sr3(NTA)2·8H2O [23]. But, the
reasons of this had not been pointed out. Only one crystal structure of the Sr-Y complex is known, so
that the reason of the anomaly of shorter intramolecular N···O distance in Sr-Y seems to be difficult
to explain.
Sa
m
pl
e
co
un
ts
Distances between intramolecular NN / Å
64 ISSN 2708-129X. Укр. хім. журн., 2022
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS
OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALSINORGANIC CHEMISTRY
765935; [Ba2(EDTA-4H)]·2.5H2O, 765936;
1104933). On the other hand, averaged intramo-
lecular N···N distances in the same EDTA-che-
lates are as follow: 3.788 Å of Li-Y, 2.993 Å of
Na-Y, 3.059 Å of K-Y, 2.891 Å of Mg-Y, 2.961
Åof Ca-Y, 3.019 Å of Sr-Y, 3.204 Å of Ba-Y. These
averaged intramolecular N···O distances in
EDTA anions (=Y4-) in addition to coordination
numbers (CN), denticity (κ), and the crystal
radii of metal ions by Shannon (1976) [50] are
displayed in Table 5.It seems that only Sr-EDTA
chelates are out of the sequence of each metalion
radius for having a short N···O distance. Simi-
larly, Polynova et al. (2009) noted that the Sr-N
bonds in the Sr-Y complex (CCDC No. 686019)
are somewhat shorter than those of strontium
nitrilotriacetate; i.e., Sr3(NTA)2·8H2O [23]. But,
the reasons of this had not been pointed out.
Only one crystal structure of the Sr-Y complex
is known, so that the reason of the anomaly of
shorter intramolecular N···O distance in Sr-Y
seems to be difficult to explain.
Table 5
Coordination numbers (CN), denticity (κ),averaged intramolecular N···O distances in metal-chelates
of EDTA anions (=Y4-), referring to the crystal radii of metal ions by Shannon 197 [50].
CN Denticity Averaged intramolecular
N···O distances / Å
Averaged intramolecular
N···N distances / Å
Crystal radii / Å
from [50]
Li-Y 5 tri-×2 2.734 3.788 0.73 (CN=4)
0.90 (CN=6)
Na-Y 7 hexa- 2.777 2.993 1.26 (CN=7)
K-Y 8 hexa- 2.805 3.059 1.65 (CN=8)
Mg-Y 7 hexa- 2.709 2.891 0.86 (CN=6)
1.03 (CN=8)
Ca-Y 8 hexa- 2.745 2.961 1.26 (CN=8)
Sr-Y 8 hexa- 2.736 3.019 1.40 (CN=8)
Ba-Y 9 tri-×2,
hexa- 2.765 3.204 1.61 (CN=9)
Recently, intramolecular distances be-
tween nitrogen and oxygen atoms (N···O) in
room-temperature phosphorescence (RTP)
emissive EDTA and salts thereof (CCDC Nos.
2051489 and 1148827) were revealed to be
similar to those of the existing RTP-emissive
clusteroluminogens according to Zheng et al.
(2021) [35]. The intramolecular non-chelate
HN+···O distances in EDTA and its salts as
shown in Fig. 3 were found to be also similar
with that of nonaromatic luminophores (Gong
et al. 2013 [36]; Chen et al. 2018 [37]). If intra-
molecular distances of nitrogen and oxygen at-
oms (N···O) determine the ability of RTP-emis-
sion in non-chelate EDTA as well as its salts in
addition to the metal-chelates of alkali metals
besides alkaline earth metals, integrated in-
formation about existing EDTA crystals de-
scribed herein would support a forthcoming
study on nonaromatic RTP, phenomenologi-
cally attracting much attention but still poorly
understood in future.
65https://ucj.org.ua
Daisuke Noguchi UCJ № 10 / Vol. 88
CONCLUSIONS. Crystallographic data of
zwitterionic ethylenediaminetetraaceti acid
(EDTA) molecules and non-chelate salts
thereof, besides the EDTA-chelates of both
alkali metals and alkaline earth metals pre-
viously reported have been searched for and
collected from the Cambridge Structural Da-
tabase (CSD). Intramolecular contact dis-
tances of ammonium-nitrogen and oxygen
atoms (NH+···O) forming hydrogen bonds
within zwitterionic EDTA molecules as well
as intramolecular NH+··· NH+ distances were
examined. According to the investigation, in-
tramolecular NH+···O distances are distributed
around 2.7 Å. In addition, NH+··· NH+ distances
seem to be divided into two groups; i.e., a small
number of gauche-forms and many anti-forms
within ethylenediamine moiety in EDTA mo
lecules. Especially, a large counterion seems to
strongly influence the conformation of EDTA
molecules. It means that crystal packings con-
tribute to change in the stability of every con-
former. The ionic radii of alkali metals as well
as alkaline earth metals in EDTA-chelates also
affect intramolecular atomic lengths, coordi-
nation numbers (CN), and denticity. In the
Sr-EDTA complex, somewhat short N···O dis-
tances compared with the series corresponding
to each metal-ion radius are occurring.
The present article has been prepared on the
basis in part of the technical reports and pre-
prints (Noguchi 2022b-e) [51-54].
ACKNOWLEDGEMENTS. Thanks to
the CCDC for making crystallographic
data available freely. This study was par-
tially funded by the Research Grant of
Nagasaki University “Doctoral Program
for World-leading Innovative and Smart
Education” for academic year 2022.
АНАЛІЗ ОСОБЛИВОСТЕЙ КРИСТАЛІЧНОЇ
СТРУКТУРИ ДЛЯ БЕЗХЕЛАТНИХ КОНФОР-
МАЦІЙ ЕТИЛЕНДІАМІНОЦТОВОЇ КИСЛОТИ
ТА ЇЇ СОЛЕЙ З ЛУЖНИМИ ТА ЛУЖНО
ЗЕМЕЛЬНИМИ МЕТАЛАМИ
Дайсуке Нагочі
Відділ освіти та підтримки досліджень,
Вища школа інженерії, Університет Нага-
сакі, Bunkyo-machi 1–14, Нагасакі 8528521,
Японія
Email: a.chemist.noguchi.d@gmail.com
У цьому дослідженні було проведено
пошук і огляд кристалічних структур нехе-
латних молекул EDTA та їхніх нехелатних
солей у стані цвіттер-іона, а також хелатів
EDTA лужних і лужноземельних металів.
Було проаналізовано 25 видів нехелатую-
чих молекул EDTA, цвіттер-іони етиленді-
амоній-діацетатдіоцтової кислоти HOOC-
CH 2-( -O O C-CH 2-)NH +-CH 2-CH 2-NH +
(-CH2-COO-)-CH2-COOH та їхні солі (ети-
лендіамоній-тетраоцтова кислота (HOOC-
CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2,
етилендіамоній-ацетат триоцтова кислота
(HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-
COO-)-CH2-COOH та етилендіамоній-те-
траацетат (-OOC-CH2-)2NH+-CH2-CH2-NH+
(-CH2-COO-)2з протиіонами, а також 17 ви
дів EDTA-хелатів іонів лужних металів (Li+,
Na+, K+, Rb+) та іони лужноземельних мета-
лів (Mg2+, Ca2+, Sr2+, Ba2+) із використанням
даних Кембриджського центру кристало-
графічних даних (CCDC). Було вивчено
кожну внутрішньомолекулярну контакт
ну відстань між атомами азоту та кисню
(HN+···O), яка становить близько 2,7 Å. Роз-
66 ISSN 2708-129X. Укр. хім. журн., 2022
ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS
OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALSINORGANIC CHEMISTRY
рахунки розподілу внутрішньомолекуляр-
них відстаней NH+ ….NH+ у молекулі ЕДТА
та її нехелатних солях довели, що великий за
об’ємом протиіон та молекули розчинника
призводять до змін кристалічної упаков-
ки через конформаційні перетворення від
гош-форми до анті (транс) форми. В існу-
ючих кристалічних EDTA-хелатах лужних
металів, а також лужноземельних металів
відображаються різні координаційні числа
(CN) і щільність (κ) аніонів EDTA; CN від 5
до 9, три- та шестизубчасті моди. Внутріш-
ньомолекулярні контактні відстаніN···O та
N···N відповідають радіусам іонів металів,
за винятком випадку хелату Sr-EDTA, ймо-
вірно, через відмінності кристалічних упа-
ковок на додачу до кількості протиіонів і
молекул кристалічного розчинника. Існую-
чі дані про кристалічну ЕДТА та її солі було
зібрані тут, що сприяє подальшому розу-
мінню та дослідженню їхнього застосуван-
ня у майбутньому.
Ключові слова: CCDC, EDTA, водневий
зв'язок, рентгенівська кристалографія.
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Cтаття надійшла 14.11.2022.
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| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-485 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:08:53Z |
| publishDate | 2022 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/cd/6658390e5698748f15a5daa29dfb15cd.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-4852026-07-22T08:23:50Z ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS Noguchi, Daisuke CCDC, EDTA, Hydrogen bonding, X-ray crystallography In the present study, the crystal structures of non-chelating EDTA molecules and their non-chelation salts in a zwitterionic state, along with the EDTA-chelates of alkali and alkaline earth metals, were searched and overviewed. 25 non-chelating molecules of EDTA, and zwitterions of ethylenediammonium-diacetate diacetic acid HOOC-CH2-(-OOC-CH2-)NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH and their salts (ethylenediammonium-tetraacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2, ethylenediammonium-acetate triacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH, and ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)2 with counterions, as well as 17 types of EDTA-chelates of alkali metal ions (Li+, Na+, K+, Rb+) and alkaline earth metal ions (Mg2+, Ca2+, Sr2+, Ba2+) were analyzed using data from the Cambridge Crystallographic Data Center (CCDC). Each intramolecular contact distance between nitrogen and oxygen atoms (NH+···O) has been examined and found to be around 2.7 Å. Investigation on the distribution of the intramolecular NH+··· NH+-distances of EDTA and non-chelated salts thereof also revealed that bulky counterion and certain crystal solvent molecules correspond to change in crystal packing, and that they influenced the conformers of EDTA molecules among gauche form to anti form. In the existing crystalline EDTA-chelates of alkali metals as well as alkaline earth metals, various coordination numbers (CN) and the denticity (к) of EDTA anions are displayed; CN 5 to 9, and tri- and hexadentate fashions. Intramolecular contact N···O and N···N distances correspond to the metal ion radii except for the case of Sr-EDTA chelate, probably due to differences of crystal packings in addition to the number of counterions and crystal solvent molecules. The existing data on crystalline EDTA and its salts have been gathered herein, which contributes to a further understanding and exploring applications hereafter. V.I.Vernadsky Institute of General and Inorganic Chemistry 2022-11-25 Article Article Inorganic Chemistry Неорганическая химия Неорганічна хімія application/pdf https://ucj.org.ua/index.php/journal/article/view/485 10.33609/2708-129X.88.10.2022.55-69 Ukrainian Chemistry Journal; Vol. 88 No. 10 (2022): Ukrainian Chemistry Journal; 55-69 Украинский химический журнал; ##issue.vol## 88 ##issue.no## 10 (2022): Ukrainian Chemistry Journal; 55-69 Український хімічний журнал; Том 88 № 10 (2022): Український хімічний журнал; 55-69 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/485/249 Copyright (c) 2022 Daisuke Noguchi https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Noguchi, Daisuke ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS |
| title | ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS |
| title_full | ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS |
| title_fullStr | ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS |
| title_full_unstemmed | ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS |
| title_short | ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS |
| title_sort | analysis of specialties of crystal structure for non-chelate conformations of ethylene-diaminetetraacetic acid and its salts with alkali and alkaline earth metals |
| topic_facet | CCDC EDTA Hydrogen bonding X-ray crystallography |
| url | https://ucj.org.ua/index.php/journal/article/view/485 |
| work_keys_str_mv | AT noguchidaisuke analysisofspecialtiesofcrystalstructurefornonchelateconformationsofethylenediaminetetraaceticacidanditssaltswithalkaliandalkalineearthmetals |