The reaction of EtNHC(S)Ph2P[double bond, length as m-dash]NP+Ph2C(S)N(-)Et (HEtSNS) with [Ru3(CO)12] has been carried out under two different experimental conditions: in the first case [Ru3(CO)12], previously turned into the labile intermediate [Ru3(CO)10(CH3CN)2], afforded, at room temperature in dichloromethane, the trinuclear clusters [Ru3(CO)11(CNEt)] (1), [Ru3(CO)9(micro-H)[(micro-S:kappa-P)Ph2PN[double bond, length as m-dash]PPh2C(S)NEt]] (2), [Ru3(CO)9(micro-H)[(micro-S:kappa-P)Ph2PN[double bond, length as m-dash]P(S)Ph2]] (3) and [Ru3(CO)10[(micro-kappa2P)Ph2PNHPPh2]] (3). Ligand fragmentation occurs via loss of EtNC or EtNCS, without sulfur transfer to the cluster core. In the second case, [Ru3(CO)12] reacted with HEtSNS in toluene at 70 degrees C, giving the trinuclear clusters , [Ru3(CO)7(CNEt)(micro3-S)[(micro2-N:eta1-C:kappa1-P)Ph2PN[double bond, length as m-dash]PPh2C(H)NEt]] (6), [Ru3(CO)8)(micro3-S)[(micro2-N:eta-C:kappa-P)Ph2PN[double bond, length as m-dash]PPh2C(H)NEt]] (6) and [Ru3(CO)6(micro3-CO)(micro3-S)(EtNC)[(micro-kappa2P) 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 , and were determined by single-crystal X-ray diffraction. Cluster preserves the original Ru3 triangular core in which an edge is bridged by a hydride ligand and by the sulfur atom of the Ph2PN[double bond, length as m-dash]PPh2C(S)NEt ligand. Cluster shows an open triangle of Ru atoms capped by a micro3-sulfide and by the unprecedented methideylamide -N(Et)CH(R)-micro3-bridging moiety of the Ph2PN[double bond, length as m-dash]PPh2C(H)NEt ligand. It formally derives from cluster by substitution of ethyl isonitrile with one CO molecule. Finally, cluster displays a Ru3(micro3-S)(micro3-CO) trigonal bipyramidal core.