Dithiocarbamate Complexes of Ti(IV) Alkoxides: Synthesis, Characterization, and Electrochemistry

Isopropoxy-and tert-butoxy-tris(dithiocarbamato)titanium(IV) complexes of five dithiocarbamate ligands were prepared and characterized by LDI-MS, H-1 NMR, C-13 NMR, and elemental analysis, as well as by crystallographic determination of two examples. Both showed strongly pi-coordinated alkoxy groups and two separate dithiocarbamate coordination environments that, in solution, were in rapid exchange. Cyclic voltammetry in CH2Cl2 revealed irreversible but reproducible oxidation peaks between +1.2 and +1.6 V vs Ag/AgCl, about 1 V positive of those from the free ligands, as well as reduction peaks in the -1.9 to -2.2 V range vs Ag/AgCl assigned to Ti-IV/III couples, and second reductions in some cases. The corresponding diisopropoxy-bis(dithiocarbamato) analogues were not isolable and slowly transformed to the more stable tris species. Indeed, these were shown to be in slow equilibrium.