Syntheses, Structures, and Reactivities of Heterobimetallic Bridging Dinitrogen Complexes Containing Group 6 and Group 4 or 5 Transition Metals1

Abstract

A series of heterobimetallic dinitrogen complexes containing group 6 and group 4 or 5 transition metals were synthesized by the reaction of the tungsten or molybdenum dinitrogen complexes cis-[W(N2)2(PMe2Ph)4] (1) and trans-[M(N2)2(dppe)2] (2) (M = W, Mo) with group 4 or group 5 compounds such as [CpTiCl3], [Cp2M‘Cl2] (M‘ = Ti, Zr, Hf), or [Cp‘M‘Cl4] (Cp‘ = Cp, Cp*; M‘ = Nb, Ta). Crystallographic studies of the complexes thus obtained including [WCl(PMe2Ph)4(μ-N2)TiCpCl2] and [WCl(PMe2Ph)4(μ-N2)NbCpCl3] revealed that the M−N−N−M‘ core is essentially linear, and the N−N bond is regarded to have the formal bond order of 2. Several μ-N2 complexes with methyl ligands at the group 4 or 5 metal center were also obtained through the reaction of dinitrogen complexes 1 and 2a (M = W) with the methyl complexes [Cp2ZrMeCl], [TaMe3Cl2], and [NbMe2Cl3]. The reaction of the complex [WCl(dppe)2(μ-N2)TiCpCl2] with Li2S5 afforded the η2-pentasulfido complex [WCl(dppe)2(μ-N2)TiCpS5], where the η2-S5 ligand forms a six-memb...