Reaction between [Ru3(CO)12] and the tridentate phosphine ligand HC(PPh2)3; X-ray crystal structures of complexes [Ru3(CO)9{Ph2PCHP(Ph)C6H4PPh}], [Ru2H(CO)4(Ph2PCHPPh2){PhPC6H4C(O)}], and [Ru2(CO)4Cl(PPh2)(dppm)]

Abstract

From the reaction of [Ru₃(CO)₁₂] with HC(PPh₂)₃ the symmetrically capped product [Ru₃(CO)₉{HC(PPh₂)₃}](1) has been isolated in low yield, together with five other complexes, [Ru₃(CO)₉{Ph₂PCHP(Ph)C₆H₄PPh}](2), [Ru₂(CO)₅Ph{(Ph₂P)₂C(H)PPh}](3), [Ru₂(CO)₄Cl(PPh₂)(dppm)](4)(dppm = Ph₂PCH₂PPh₂), [Ru₂H(CO)₄(Ph₂PCHPPh₂)(PhPC₆H₄)](5), and [Ru₂H(CO)₄(Ph₂PCHPPh₂){PhPC₆H₄C(O)}](6). Complexes (1)–(6) have been characterised by i.r.,¹H, ³¹P, and ¹³C n.m.r. spectroscopy. In addition, the structures of complexes (2), (4), and (6) have been determined by single-crystal X-ray diffraction methods. In (2), the HC(PPh₂)₃ ligand has undergone a reaction of which the end result is an ortho-substitution of a phenyl ring of one phosphine moiety by the phosphorus atom of a second phosphine moiety, together with the loss of C₆H₆. The resulting Ph₂PC(H)P(Ph)C₆H₄P(Ph) ligand caps the Ru₃ triangle. In (4), the dppm, the PPh₂, and the chloride ligands all bridge the Ru–Ru bond. In (6), the Ph₂PCHPPh₂ ligand bridges the Ru–Ru bond, and the central carbon atom is also bonded to one of the Ru atoms to form a three-membered Ru–P–C ring. Also bridging the Ru–Ru bond is a hydride and a PhPC₆H₄C(O) ligand with which both Ru atoms form bonds to the phosphorus atom and one of the Ru atoms is also bonded to the acyl carbon to form a functional acyl ligand. Pathways to all these complexes are proposed.