Synthesis and Structural Characterization of Zirconium−Carboryne Complexes

A series of Zr−carboryne (carboryne = 1,2-dehydro-1,2-carborane) complexes were prepared and fully characterized. Both the electronic and steric factors of the ligands have significant effects on the formation of the resultant metal complexes. The reaction of organozirconium dichloride with 1 equiv of Li2C2B10H10 gave a new class of zirconium−carboryne complexes, including (η2-C2B10H10)ZrCl2(THF)3 (6). Treatment of 6 with 2 equiv of amidinatolithium, guanidinatolithium, or tBuOK afforded the complex [η2-CyNC(CH3)NCy]2Zr(η2-C2B10H10) (4), [η2-nPr2NC(NPri)2]2Zr(η2-C2B10H10) (7), or [(η2-C2B10H10)2Zr(OtBu)(THF)][Zr(OBut)3(THF)3] (8). The unexpected product [σ:σ:σ-{tBuC(O)CHC(tBu)(O)C2B10H10}]Zr(η2-tBuCOCHCOBut)(THF)2 (9) was isolated from the reaction of 6 with (tBuCOCHCOtBu)Na. All complexes were fully characterized by 1H, 13C, and 11B NMR techniques as well as elemental analyses. Their structures were further confirmed by single-crystal X-ray analyses.