INVESTIGATION OF THE SYNTHESIS CONDI­TI­ONS, COMPOSITION AND STRUCTURE OF Ni(II) TETRAFLUOROBATE COMPLEXES WITH ISOMERIC PHENYLENEDIAMINE

• Date: 2024
• Main Authors: Shestakova, Maryna, Lyashenko, Olexandr, Ivanova, Roxana, Shpota, Olena, Peretyaka, Sergiy, Filiptsova, Kateryna
• Format: Article
• Language: English
• Published: V.I.Vernadsky Institute of General and Inorganic Chemistry 2024
• Online Access: https://ucj.org.ua/index.php/journal/article/view/653
• Journal Title: Ukrainian Chemistry Journal

Complex tetrafluoroborates of Ni (II) with nitrogen-containing organic bases o-, m- and p-phenylenediamines (L) were synthesized. The composition and structure of the synthesized compounds were determined using a number of physico-chemical research me­thods. It was established that complexes of the general formula [NiL4](BF4)2 are formed for m- and p-isomers regardless of the synthesis conditions. In the case of o-PDA synthesis without a solvent at a 1:2 ratio of components gave the complex [Ni(o-PDA)2](BF4)2. The use of a solvent led to the formation of a ge­teroligand complex [Ni(o-PDA)2(H2O)2](BF4)2 due to the inclusion of two water molecules in the coordination sphere. The coordination centers of organic ligands and the nature of binding of the BF4- group were determined by IR spectroscopy. In the IR spectra of complex tetrafluoroborates the shift values of the νas(NH) bands in the low-frequency region indicate the formation of a metal-nitrogen coordination bond. The change in absorption bands of o-FDA in the IR spectra of the corresponding complexes corresponds to the bidentate character of this ligand. The nature of the absorption bands of valence and deformation vibrations of the tetrafluoroborate ion in compounds with m- and p-phenylenediamines and [Ni(o-PDA)2(H2O)2](BF4)2 indicates the preservation of the symmetry type of Td anion and its outer-sphere coordination. In the [Ni(o-PDA)2](BF4)2 spectrum the vibrational characteristics of the tetrafluoro­borate ion indicate the "semi-coordination" of the tetrafluoroborate ion. Based on the diffuse reflectance spectra analysis and the data of magnetic susceptibility measurements the octahedral structure of the coordination polyhedron for [Ni(o-PDA)2(H2O)2](BF4)2 and tetrahedral for compounds with m- and p-PDA was established. The [Ni(o-PDA)2](BF4)2 complex has a squareplanar structure. The results of the conducted investigation confirm the previously obtained dependence of the composition and structure of complex tetrafluoroborates on the electron-donor ability of organic ligands.