Synthesis and characterization of titanium and zirconium complexes bearing diphenyltriazenido ligands

Abstract

Treatment of tetrakis(dimethylamido)titanium(IV) and tetrakis(diethylamido)titanium(IV) with two equivalents of 1,3-diphenyltriazene in hexane afforded bis(dimethylamido)bis(1,3-diphenyltriazenido)titanium(IV) (62%) and bis(diethylamido)bis(1,3-diphenyltriazenido)titanium(IV) (68%), respectively, as deep red crystalline solids. Reaction of tetrakis(dimethylamido)titanium(IV) with more than two equivalents of 1,3-diphenyltriazene in refluxing toluene did not lead to substitution of more than two dimethylamido ligands, but only gave extensive decomposition. Treatment of tetrakis(dimethylamido) zirconium(IV) with four equivalents of 1,3-diphenyltriazene in hexane afforded tetrakis(1,3-diphenyltriazenido)-zirconium(IV) (79%) as a deep red crystalline solid. Crystal structures of bis(dimethylamido) tetrakis(1,3-diphenyltriazenido)zirconium(IV) were determined. The titanium complexes exhibit octahedral coordination spheres with cis-dialkylamido ligands, while the zirconium complex is eight-coordinate with η 2-1,3-diphenyltriazenido ligands. Solution molecular weight measurements for tetrakis(1,3-diphenyltriazenido)zirconium(IV) indicated a monomeric structure in benzene, consistent with the structural results.