The possibility of obtaining mixed-anion complexes of cadmium and zinc with various combinations of monocarboxylic acid anions was investigated. The combination of pentafluorobenzoate (Pfb), benzoate (Bz) anions, with 1,10-phenanthroline (Phen) within a single compound leads to the formation of crystals of previously reported homoanionic complexes. When using 2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenylacetate (Tfpha) or 3,5-dinitrobenzoate (Dnb) anions instead of pentafluorobenzoate, it was possible to isolate mixed-anion compounds Cd(Phen)(Tfpha)(Bz) (I), Cd(Phen)(Dnb)(Bz)Cd(Phen)(Dnb)(Bz) (II), Zn(Phen)(Dnb)(Bz) · 2(CH) (III), ZnCd(Phen)(Dnb)(Bz) · 3 (CH) · (MeOH) (IV). In the structure of compounds II and IV, according to X-ray diffraction data, in some anion sites the Bz-and Dnb-anions are refined simultaneously with different occupancies. Using the compounds Cd(Phen)-(Dnb)(Pha) (V) and Zn(HO)(Phen)(Dnb)(Pha)·MeCN (VI, Pha – phenylacetate anion) as examples, it is shown that mixed-anion complexes can also be formed when a conformationally flexible phenylacetate anion is combined with a stereochemically more rigid 3,5-dinitrobenzoate anion at zinc and cadmium centers. The synthesized compounds were characterized by X-ray diffraction analysis (CCDC nos. 2443227, 2443228, 2443229, 2443230, 2443231, and 2443232, respectively), IR spectroscopy, and CHN analysis. It has been found that the main contribution to the stabilization of the crystal packings is provided by π···π, C–H···F, N–O···π, and NO···NO.
Shmelev et al. (Wed,) studied this question.