Synthesis and reactivity of isocyanatogoldtriosmium clusters

Abstract

Syntheses of [Os₃(CO)₁₁{Au(PR₃)}(NCO)] and [Os₃(CO)₁₀{Au(PR₃)}(NCO)](R = Et or Ph) by treating [Os₃(CO)₁₂] with azide anions in the presence of [Au(PR₃)Cl] have been developed. Control experiments indicate that no reaction occurs without [Au(PR₃)Cl], and that [Au(PR₃)(N₃)] is not an intermediate. A similar reaction using nitrite in place of azide gave [Os₃(CO)₁₀{Au(PEt₃)}(NO)]. [Os₃(CO)₁₀{Au(PEt₃)}(NCO)] reacts with nucleophilic reagents (HY) to give [Os₃(CO)₁₀{Au(PEt₃)}(NHCOY)][Y = OH, OMe, PhCH₂NH, or PhCH₂CH(CO₂Me)NH]; with phosphines to give [Os₃(CO)₉(PPh₃){Au(PR₃)}(NCO)](R = Et or Ph) and [Os₃(CO)₉(PEt₃)₃]; and with BH₃·thf (thf = tetrahydrofuran) to give [Os₃(CO)₁₀{Au(PEt₃)}(NHCHO)]. Reaction of [Os₃(CO)₁₀{Au(PEt₃)}(NCO)] with PhNPPh₃ produces [Os₃(CO)₁₀{Au(PEt₃)}(NCNPh)], which in turn can react with PhCH₂NH₂ to form the compound [Os₃(CO)₁₀{Au(PEt₃)}(NHCNPhNHCH₂Ph)] and is reduced to [Os₃(CO)₁₀{Au(PEt₃)}(NHCHNPh)] by BH₃·thf.