Titanium(IV) phosphinoamide as a unique bidentate ligand for late transition metals II: Tisingle bondRu heterobimetallics bearing a bridging chlorine atom

Treatment of a titanium phosphinoamide, (Ph2PNtBu)2TiCl2 (1), with [Cp∗RuCl]4 in THF at room temperature afforded a Tisingle bondRu heterobimetallic complex, of which crystallographic study showed the molecular structure to be a six-membered dimetallacyclohexane, Cp∗Ru(μ-Cl)(Ph2PNtBu)2Tidouble bond; length as m-dashO (3). A boat conformation of the dimetallacycle leads to effective linking of the two metal centers by two phosphinoamide ligands, and bridging of a chlorine atom over the Tisingle bondRu axis. The Tisingle bondRu heterobimetallics were synthesized by the reaction of 1 with Cp∗Ru(COD)Cl or Cp∗Ru(TMEDA)Cl, whereas no reaction occurred between 1 and Cp∗Ru(PCy3)Cl. A primary product of this reaction would be a trichloride, Cp∗Ru(μ-Cl)(Ph2PNtBu)2TiCl2 (2). In fact, careful treatment of 1 with [Cp∗RuCl]4 afforded 2 as the main product which was detected by NMR and ESI-MS spectra; 2 was converted to 3 in contact with 1 equivalent of water.