American Chemical Society
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Reactivity of a Titanium Dinitrogen Complex Supported by Guanidinate Ligands:  Investigation of Solution Behavior and a Novel Rearrangement of Guanidinate Ligands

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journal contribution
posted on 2001-11-22, 00:00 authored by Sarah M. Mullins, Andrew P. Duncan, Robert G. Bergman, John Arnold
The titanium dinitrogen complex, {[(Me2N)C(NiPr)2] 2Ti}2(N2) (2), was synthesized by reduction of the dichloride precursor, [(Me2N)C(NiPr)2] 2TiCl2 (1). The dinitrogen complex reacts with phenyl azide to yield the titanium imido complex, [(Me2N)C(NiPr)2]2TiNPh (3). The fluxional behavior of the guanidinate ligands in compounds 13 was investigated using variable temperature and two-dimensional NMR techniques; guanidinate ligand rotation and racemization reactions were observed. Rearrangement of the 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 for the bridging sulfido complex 5; the structure of this compound is sensitive to temperature and solvent. The solid-state and solution structures of compounds 15 are discussed.