Reactivity of a titanium dinitrogen complex supported by guanidinate ligands: Investigation of solution behavior and a novel rearrangement of guanidinate ligands

The titanium dinitrogen complex, {[(Me2N)C((NPr)-Pr-i)(2)] Ti-2}(2)(N-2) (2), was synthesized by reduction of the dichloride precursor, [(Me2N)C((NPr)-Pr-i)(2)] 2TiCl2 (1). The dinitrogen complex reacts with phenyl azide to yield the titanium imido complex, [(Me2N)C(NiPr)(2)](2)TiNPh (3). The fluxional behavior of the guanidinate ligands in Compounds 1-3 was investigated using variable temperature and two-dimensional NMR technique.,,: guanidinate ligand rotation and racemization reactions were observed. Rearrangement of die guanidinate ligand to an asymmetrical bonding mode utilizing the dimethylamino and amide-nitrogen atoms is observed in the bridging oxo and sulfido derivatives (4 and 5). These compounds are formed by the reactions of 2 with pyridine N-oxide and propylene sulfide, respectively. The ligand rearrangement was observed to be reversible fur the bridging sulfido complex 5; the structure of this compound is sensitive to temperature and solvent. The solid-state and solution Structures of compounds 1-5 are discussed.