Synthesis and photochemical reactivity of phenylthioureatotriosmium cluster complexes: crystal structures of [Os3H(CO)10{µ-SC(NPh)(NHPh)}] and [Os3H(CO)9{µ3-SC(NPh)(NHPh)}]

Abstract

The reaction of [Os₃(CO)₁₀(MeCN)₂] with phenylthiourea (HL¹) and N,N′-diphenylthiourea (HL²) yielded the thioureatotriosmium cluster complexes [Os₃H(CO)₁₀(µ-L)](L = L¹ or L²) in which the thioureate moiety L bridges two osmium atoms via the sulfur atom. The complexes underwent photochemical reactions with a nitrogen atom of the thioureate ligand displacing a carbonyl on the third osmium atom to give [Os₃H(CO)₉(µ₃-L)](L = L¹ or L²). These reactions proceed cleanly and the quantum yields and apparent activation energies have been determined. The cluster complexes have been characterized by spectroscopic means and the structures of [Os₃H(CO)₁₀(µ-L²)] and [Os₃H(CO)₉(µ₃-L²)] have been determined by X-ray diffraction: [Os₃H(CO)₁₀(µ-L²)], triclinic, space group P, a= 11.607(3), b= 14.341(3), c= 9.520(3)Å, α= 104.92(2), β= 112.62(2), γ= 94.02(2)°, and Z= 2, [Os₃H(CO)₉(µ₃-L²)], monoclinic, space group P2₁/m, a= 9.583(3), b= 14.249(3), c= 9.969(3)Å, β= 103.53(2)°, and Z= 2. The structures were refined to R= 0.035 and 0.046 for 3791 and 3987 unique diffraction data respectively. In both clusters one edge of the osmium triangle is bridged by a sulfur atom and in [Os₃H(CO)₉(µ₃-L²)] one of the nitrogen atoms of the thioureate ligand has displaced a carbonyl from the third osmium of the cluster.