Syntheses and structural characterization of new dithiophosphinato cadmium complexes

Abstract

New cadmium complexes of 4-methoxyphenyl dithiophosphinic acids, H3CO-C6 H 4-(R)PS2H were prepared. The five dithiophosphinato ligands (L) involved were of the general structure H3CO-C6 H 4-(R)PS2- with R = 3-methylbutyl, (L1); n-butyl, (L2); 2-methylpropyl, (L3); 1-methylpropyl, (L4) and 2-propyl, (L5). To the best of our knowledge, this is the first report on the preparation and characterization of the n-butyl- derivative. The acid forms of the ligands were obtained by treatment of the Lawesson reagent, (LR) [2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide] with the corresponding Grignard reagent in dry diethylether. The acids formed were transformed into easily crystallizable ammonium salts (NH4L) for purification. These salts were treated with CdCl2 in ethanol at room temperature to produce the bis-dithiophosphinato cadmium complexes ([Cd(L)2]2) exclusively. The structures of the complexes were elucidated by elemental analysis, MS, FTIR and Raman spectroscopy techniques as well as 1H-, 13C- and 31P- NMR. The crystal structures of [Cd(L1)2]2 and [Cd(L2)2]2 were also studied as examples. X-ray studies confirmed the nonplanar, four-coordination geometry of the complexes and indicate that electron delocalization prevails in the PS2-moiety of the dithiophosphinato groups.