Triosmium clusters containing bridging dppm and PhSe ligands: X-ray crystal structure of [(μ-H)Os₃(CO)₈(μ-SePh)(μ-dppm)]

Abstract

Treatment of [(μ-H)Os₃(CO)₈{Ph₂PCH₂P(Ph)C₆H₄}] <b>2</b> with phenylselenol at room temperature gives [(μ-H)Os₃(CO)₈(μ-SePh)(μ-dppm)]<b>3</b> and [(μ-H)Os₃(CO)₈(μ-SePh) (η¹-SePh){ Ph₂PCH₂P(Ph)C₆H₄}] <b>4</b> in 49 and 6% yields, respectively. The reaction of [Os₃(CO)₁₀(μ-dppm)] <b>1 </b>with phenylselenol at 110°C gives <b>3</b> in 27% yield. When irradiated (UV) under an atmosphere of CO, <b>3</b> eliminates benzene and is transformed to [Os₃ (CO)₇(μ₃-CO)(μ-Se)(μ-dppm)] <b>5</b>. Compound <b>3</b> reacts with excess CF₃COOH to give the cationic hydrido derivative [(μ-H)₂Os₃(CO)₈(μ-SePh)(μ-dppm)]⁺ <b>6</b>, isolated as PF₆ salts in good yield. All the compounds have been characterized by spectroscopic data, including an X-ray structure determination for <b>3</b>. Compound <b>3</b> crystallizes in the triclinic space group <i>P-1 </i>with <i>a=</i>11.5354(2), <i>b= </i>12.6493(2), <i>c</i>=l5.1523(2) Å, α<i>= </i>112.9239(6), β=91.4324 (7), γ= 106.4148(6)^o, <i>V= </i>1902.90(5) ų and Z=2. The compound consists of an isosceles triangle

of osmium atoms, one edge of which is simultaneously bridged by a SePh group and a hydride ligand while one of the other edges is spanned by the dppm ligand.