Syntheses and structural characterization of new dithiophosphinato cadmium complexes

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.