Polymeric octahedral and monomeric tetrahedral Group 12 pseudohalogeno (NCX−: X=O, S, Se) complexes of 4-(N,N-dimethylamino)pyridine

A series of new pseudohalogeno complexes of Zn(II), Cd(II) and Hg(II) with 4-(N,N-dimethylamino)pyridine (4-dmap) has been prepared. The compounds Zn(NCS)2L2 (1), Cd(NCS)2L2 (2a), Hg1.5(NCS)3L2 (3), Zn(NCO)2L2 (4), Cd(NCO)2L2 (5), Hg(NCO)2L (6), Zn(NCSe)2L2 (7) and Cd(NCSe)2L2 (8a) (L=4-dmap) were characterized by elemental analyses, mid and far IR, 1H and 13C NMR spectroscopy, and differential scanning calorimetry. The structures of 1, 2a, 4 and 8a have been confirmed by X-ray crystallography. In addition, molecular geometries of Cd(NCS)2L2·2DMSO (2b) and Cd(NCSe)2L2·2DMSO (8b) have been determined by X-ray crystallography. Compounds 1 and 4 consist of monomeric units in which the Zn(II) atoms are tetrahedrally surrounded by two N-donating pseudohalide ions and two 4-dmap moities, coordinating at the endocyclic nitrogen atom. Complexes 2a and 8a are isostructural polymers comprised of chains of the monomeric unit MX2N2, where X is NCS− or NCSe−. Within each monomeric unit one pseudohalide ligand is bound through the chalcogen atom; the other through the nitrogen atom. The polymer chain is a distorted octahedron sharing common edges through nearly linear bridging pseudohalide groups displaced trans to each other; the two 4-dmap ligands are also displaced trans to each other. Complexes 2b and 8b are isostructural monomeric units, in which the central Cd(II) atom exhibits an N4O2 octahedral geometry.