cis-Dichloro complexes of Ni-II, Pd-II, and Pt-II derived from 2-pyridylmethyl-N-substituted imines

Synthesis and structural characterization of cis-dichlorocomplexes derived from 2-pyridylmethyl-N-methylimine (1), 2-pyridylmethyl-N-ethylimine (2), and 2-pyridylmethyl-N-(2-bromophenyl)imine (3) of general formula [M-II{(C5H4N)-C(H)=NR}(n)Cl-2] {M = Ni, Pd, Pt; R = Me, Et, -(2-Br-C6H4); n = 1, 2} are described. Paramagnetic complexes of Ni-II (1a-3a) were identified by elemental analyses, vibrational spectroscopy and for 2a and 3a, by electronic spectroscopy; the complexes of Pd-II (1b-3b) and Pt-II (1c-3c) were characterized by elemental analyses, vibrational spectroscopy and NMR. X-ray molecular structures of 1a, 2a, 1b-3b, 2c and 3c displayed a bidentate coordination mode of the N-substituted pyridylimines (1-3) towards the metallic atoms with the formation of five-membered chelate rings and the chlorine atoms in a cis coordination. In 1a and 2a a distorted octahedral local geometry around the nickel atom was observed, whereas a distorted square planar local geometry around the palladium and platinum atoms in the compounds 1b-3b, 2c and 3c was displayed.