Zinc complexes of the N,N,S ligand (mercaptophenyl)(picolyl)amine

The zinc complex chemistry of the tridentate thiol ligand N-(2-mercaptophenyl) (2-picolyl)amine (MPPAH) differs considerably from that of the aliphatic analogue N-(2-mercaptoethyl) (2-picolyl)amine reported previously. This is due to the lower basicity and hence bridging tendency of its aromatic thiolate function. With zinc salts of oxo anions the 1:1 complexes (MPPA)ZnX (la-c: X = ONO2, OAc, OBz) are formed which according to spectroscopic data are monomeric while the halide (MPPA)ZnBr (2) seems to be polymeric. In the absence of coordinating anions the monomeric 2:1 complex (MPPA)(2)Zn (3) results which according to a crystal structure determination contains tetrahedral zinc coordinated by one MPPA Ligand in a tridentate fashion while the other is only monodentate and sulfur-bound. A similar N2S2 coordination can be deduced for the 1:1:1 complex (MPPA)Zn(STrt) (4) resulting from ZnEt(2), MPPAH and triphenylmethanethiol.