Naslov
Anion influence on polymerization of Cd(II) picolinamide complexes

Autori
Balić, Tomislav ; Popović, Zora ; Marković, Berislav

Izvornik
Inorganica chimica acta (0020-1693) 478 (2018), 1; 32-46

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Cadmium(II) ; Picolinamide ; Coordination polymer ; Anion influence

Sažetak
The reactions of picolinamide (pyridine-2-carboxamide, pia) with various cadmium(II) salts in aqueous media were investigated. With cadmium(II) halides, three novel coordination polymers (CPs) were isolated, namely: [CdX2(pia)]n (X = Cl (1), Br (2), I (3). Cadmium(II) sulphate gave [Cd(SO4)(pia)(H2O)3] ·2H2O (4) while cadmium(II) nitrate in the presence of perchlorate ions gave mixed complex [Cd(pia)3(H2O)](NO3)(ClO4) (5) with both anions acting as counterions. All isolated complexes were identified by chemical analysis and characterized using IR-spectroscopy and thermal methods (TG/DSC). X-ray crystal structure analysis of 1-3 revealed a distorted octahedral coordination of Cd(II) which consists of four halide and N, O-chelated pia ligands. The chain propagation is achieved through metal-halide double-bridges. The pia ligand is in cis geometry (cis-configured polymeric chain) and the topology of chains can be described as zig-zag. In 1 the neighbouring chains are mutually linked through weak C–H Cl and N–H Cl hydrogen bonds into 3D supramolecular framework. In 2 and 3, which are isostructural, unlike in 1 the neighbouring chains are linked by a strong head-to-head amide hydrogen bonds (graph set R22(8)) into supramolecular sheets in (0 1 0) planes and through weak C–H X interactions a 3D supramolecular framework is accomplished. In discrete molecules of 4 and 5 a distorted octahedral and pentagonal bipyramidal coordination of Cd(II) ion is revealed respectively. The final 3D supramolecular dimensionality of 4 and 5 is achieved through non-covalent interactions including sulphate ions in the former, and perchlorate and nitrate ions in the later thus pointing a discernible influence of anions on the structure.

Izvorni jezik
Engleski

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