Metal chelates of dithiocarbazic acid and its derivatives. VI. Antiferromagnetic and ferromagnetic interactions in some copper(II) complexes of salicylaldehyde and acetylacetone Schiff bases derived from s-methyldithiocarbazate

Abstract

The Schiff base S-methyl-β-N-(2-hydroxyphenyl)methylendithiocarbazate, o-HO.C 6H 4CHNNHC(S)SCH 3, and the corresponding 5chloro, 5-bromo, 5-nitro, and 3-methoxy derivatives were prepared from the appropriate salicylaldehyde and S-methyldithiocarbazate. The acetylacetone Schiff base 2-hydroxy-4-methyl-5,6-diaza-7-thiono-8-thianona-2,4-diene, CH 3C(OH)CHC(CH 3)NNHC(S)SCH 3, was also prepared. By the loss of two protons the ligands behave as doubly negatively charged ONS tridentates. Complexes of the type M(ONS).B (M = Cu,Ni; B = py, H 2O) and Co III(ONS)(ONSH) were isolated. In addition, the complexes M(ONS) (M = Cu, Ni, Pd, Pt) were obtained. It is suggested that where M = Ni, Pd, Pt, the complexes possess square-planar, dimeric thiolo-bridged structures. The copper complexes Cu(ONS) of the 5-chloro,5-bromo-, and 3-methoxy- salicylaldehyde Schiff bases are red and have anomalously low moments which decrease with decrease in temperature. This behaviour is attributed to antiferromagnetic interaction due to an oxygen-bridged dimeric structure. The moment of the green copper complex of the 5-nitro-salicylaldehyde Schiff base increases with decrease in temperature, indicating ferromagnetic interaction between the copper atoms. The value of the moment at 83′K is 2.43 B.M. and the magnetic data fit the expression for a tetrahedral cluster of four ferromagnetically interacting copper atoms. The green copper complex of the acetylacetone Schiff base is also ferromagnetic.