Syntheses, structures, and reactivities of f heterobimetallic bridging dinitrogen complexes containing group 6 and group 4 or 5 transition metals

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 cz's-[W(N2)2(PMe2Ph)4] (1) and irans-[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(H-N2)TiCpCl2] and [WCl(PMe2Ph)4CH-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 -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], [TaMeaCl2], and [NbMe2Cl3]. The reaction of the complex [WCl(dppe)2(H-N2)TiCpCl2] with Li2S5: afforded the ?/2-pentasulfido complex [WCl(dppe)2(N2)TiCpS5], where the ?/2-Ss ligand forms a six-membered chelate ring with the chair conformation. Protonation of the -N2 complexes having PMe2Ph ligands gave NHs in moderate yield, concurrent with the formation of a small amo'unt of NH2NH2.