ic5b01962_si_002.cif (431.43 kB)

Heterobimetallic Ti/Co Complexes That Promote Catalytic N–N Bond Cleavage

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posted on 16.11.2015, 00:00 by Bing Wu, Kathryn M. Gramigna, Mark W. Bezpalko, Bruce M. Foxman, Christine M. Thomas
Treatment of the tris­(phosphinoamide) titanium precursor ClTi­(XylNPiPr2)3 (1) with CoI2 leads to the heterobimetallic complex (η2-iPr2PNXyl)­Ti­(XylNPiPr2)2(μ-Cl)­CoI (2). One-electron reduction of 2 affords (η2-iPr2PNXyl)­Ti­(XylNPiPr2)2CoI (3), which can be reduced by another electron under dinitrogen to generate the reduced diamagnetic complex (THF)­Ti­(XylNPiPr2)3CoN2 (4). The removal of the dinitrogen ligand from 4 under vacuum affords (THF)­Ti­(XylNPiPr2)3Co (5), which features a Ti–Co triple bond. Treatment of 4 with hydrazine or methyl hydrazine results in N–N bond cleavage and affords the new diamagnetic complexes (L)­Ti­(XylNPiPr2)3CoN2 (L = NH3 (6), MeNH2 (7)). Complexes 4, 5, and 6 have been shown to catalyze the disproportionation of hydrazine into ammonia and dinitrogen gas through a mechanism involving a diazene intermediate.