Synthesis, characterisation and crystal structures of new nickel complexes in S_4 coordination spheres; an unprecedened rearrangement during ligand synthesis

摘要

Two new nickel(II) complexes were synthesized with an S_4 coordination environment. These complexes were synthesized by in situ deprotection of thiouronium salts in the presence of nickel(II). The ligands used are 4-mercapto-3,3-methyl-1-phenyl-2-thiabutane (Hbsms) and alpha,alpha'-bis(4-mercapto-3,3-methyl-2-thiabutyl)-o-xylene (H_2xbsms). The former is a didentate ligand containing one thioether and one thioate group and the latter is a dithioether dithiolate tetradentate ligand. The differences between these ligands upon coordination to nickel have been investigated. During the synthesis of these ligands, an unprecedented spontaneous rearrangement occrs, which is very fast and selective to a single product. The complexes were characterized by analytical, spectroscopic and electrochemical methods. The geometry of the nickel complexes is square planar according to the single-crystal X-ray structures. In [Ni(bsms)_2] the two ligands are coordinated with the thiolates in trans positions towards each other; in [Ni(xbsms)] the thiolates are in enforced cis positions. [Ni(bsms)_2] crystallizes in the triclinic space group P1 and has one centrosymmetric molecule in the unit cell. [Ni(xbsms)] crystallizes in the monoclinic space group KP2_1/c with two independent molecules in the asymmetric unit, however, the differences between these two molecules are very small. The Ni-S dstances are 2.1730(4)-2.1909(6)A and in the common range for thiolates and chelating thioethers.