Inorganic Chemistry, Vol.46, No.16, 6373-6381, 2007
Synthesis, structure, and LLCT transitions in terminal hydrazido(2-) bipyridine complexes of titanium
Addition of 2,2'-bipyridine and its derivatives to Ti(NMe2)(2)(dpma), where dpma is N,N-di(pyrrolyl-alpha-methyl)-N-methylamine, followed by various hydrazine derivatives was used to generate a series of terminal hydrazido(2-) complexes. Among the new complexes is Ti[=NN(H)Ph](Bu-t-bpy)(dpma), which was structurally characterized, where Bu-t-bpy is 4,4'-tert-butyl-2,2'- bipyridine. Other new complexes reported are Ti(NNMe2)(Me-bpy)(dpma), Ti-(NNMe2)(bpy)(dpma), Ti(NNMe2)(Ph-bpy)(dpma), Ti[NN(Me)Ph](Bu-t- bpy)(dpma), Ti[NN(Me)p-tolyl](Bu-t-bpy)(dpma), and Ti[NN(Me)4-FC6H4](Bu-t-bpy)(dpma). Titanium hydrazido(2-) complexes bearing bpy substituents possess a low-energy transition, leading them to have blue or green colors, which is somewhat unusual for titanium(IV) species. Through absorption studies on the derivatives, it was determined that the low-energy transition is the result of an unusual ligand-to-ligand charge transfer where electron density residing on the hydrazido(2-) is transferred to the bpy pi* orbitals.