TETRANUCLEAR RUTHENIUM CLUSTERS CONTAINING A PSEUDO-OCTAHEDRAL RU4S2 FRAMEWORK AND DIAMINOCARBENE LIGANDS

The tetranuclear ruthenium clusters [Ru4(CO)6(mu-CO)3(mu(a)-S)2{CNHR)2}2] 1 (R = Pr(i)) and 3 (R = Et) and [Ru4(CO)7(mu-CO)3(mu(4)-S)2{C(NHR)2}] 2 (R = Pr(i)) and 4 (R = Et) were obtained from the thermal reaction of [Ru3(CO)12] with thioureas SC(NHR)2 (R - Pr(i) or Et). In the case of diethylthiourea, a trinuclear cluster [Ru3(mu-H) (CO)9(mu(3)-NEtCSNHEt)] 5 was isolated in addition to 3 and 4. The single-crystal X-ray structure analyses of 1 and 2 reveal a pseudo-octahedral Ru4S2 skeleton with three mu-carbonyl bridges in the Ru4 plane; 1 has two terminal diaminocarbene ligands and six terminal carbonyls, whereas there is only one terminal diaminocarbene ligand but seven terminal carbonyls in 2.