Reactivity of the zwitterionic ligand EtNHC(S) Ph2P=NPPh2C(S)NEt towards [Ru3(CO)12]. Sulfur transfer and ligand fragmentation leading to the methideylamide[-N(Et)-CH(R)-] μ3-bridging moiety

The reaction of EtNHC(S)Ph2P=NP+Ph2C(S)N-Et (HEtSNS) with [Ru-3(CO)(12)] has been carried out under two different experimental conditions: in the first case [Ru-3(CO)(12)], previously turned into the labile intermediate [Ru-3(CO)(10)(CH3CN)(2)], afforded, at room temperature in dichloromethane, the trinuclear clusters [Ru-3(CO)(11)(CNEt)] (1), {Ru-3(CO)(9)(mu-H)[(mu-S: kappa-P) Ph2PN= PPh2C(S) NEt]} (2), {Ru-3(CO)(9)(mu-H)[(mu-S: kappa-P) Ph2PN= P(S) Ph-2]} (3) and {Ru-3(CO)(10)[(mu-kappa P-2)Ph2PNHPPh2]} (4). Ligand fragmentation occurs via loss of EtNC or EtNCS, without sulfur transfer to the cluster core. In the second case, [Ru-3(CO)(12)] reacted with HEtSNS in toluene at 70 degrees C, giving the trinuclear clusters 4, {Ru-3(CO)(7)(CNEt)(mu(3)-S)[(mu(2)-N: eta(1)-C: kappa(1)-P) Ph2PN= PPh2C(H) NEt]} (5), {Ru-3(CO)(8))(mu(3)-S)[(mu(2)-N:eta-C: kappa-P) Ph2PN= PPh2C(H) NEt]} (6) and {Ru-3(CO)(6)(mu(3)- CO)(mu(3)-S)(EtNC)[(mu-k(2)P) Ph2PNHPPh2]} (7). The last three compounds derive from ligand fragmentation and sulfur transfer to the metal cluster. All compounds were characterized by spectroscopy (NMR, IR) and the molecular structures of 2, 5 and 7 were determined by single-crystal X-ray diffraction. Cluster 2 preserves the original Ru-3 triangular core in which an edge is bridged by a hydride ligand and by the sulfur atom of the Ph2PN= PPh2C(S) NEt ligand. Cluster 5 shows an open triangle of Ru atoms capped by a mu(3)-sulfide and by the unprecedented methideylamide -N(Et)CH(R)-mu(3)-bridging moiety of the Ph2PN= PPh2C(H) NEt ligand. It formally derives from cluster 6 by substitution of ethyl isonitrile with one CO molecule. Finally, cluster 7 displays a Ru-3(mu(3)-S)(mu(3)-CO) trigonal bipyramidal core.