Reactions of [H₂Os₃(CO)₁₀] with Conjugated Diynes (RC₂C₂R‘) Containing Nucleophilic Oxygen in β Position of a Substituent (R = Ph, R‘ = CH₂OH, C(O)Ph; R = R‘ = CMe₂(OH))

Abstract

Reactions of [H 2 Os 3 (CO) 10 ] with a series of diynes, RC 2 C 2 R‘ ( 1: R = Ph, R‘ = CH 2 OH; 2: R = Ph, R‘ = C(O)Ph; 3: R = R‘ = C(OH)Me 2 ), have been studied. It was found that upon coordination to the triosmium cluster, the nucleophilic oxygens of the R‘ substituents of 1 and 2 take part in intramolecular cyclization reactions to give [HOs 3 (CO) 10 {μ-η 1:η 2 -PhCH 2 (C CH−C CH−O)}] ( 5 ) and [HOs 3 (CO) 10 {μ-η 1:η 1 -Ph(C CH−C C−O)CPh}] ( 6 ), respectively, both of which contain furan rings coordinated to the cluster core. On heating of the latter compound, the furan moiety remains intact, but a carbonyl group dissociates from the cluster, leading to the formation of [HOs 3 (CO) 9 (μ 3 -η 1:η 3:η 1 -Ph(C CH−C C−O)CPh)] ( 7 ) with a closed “C 3 Os 3 ” pentagonal pyramidal structure. Reaction of [H 2 Os 3 (CO) 10 ] with 3 does not lead to cyclization of the diyne; instead, the clusters [Os 3 (CO) 10 {μ 3 -η 2 -(RCH CH−C 2 R)}] ( 8 ) and [Os 3 (CO) 10 {μ 3 -η 2 -(RC 2 C 2 R)}] ( 9 ) are formed. Deuterium labeling of the starting compounds has been used in the reaction of [H 2 Os 3 (CO) 10 ] with HOCH 2 C 2 C 2 CH 2 OH in order to investigate possible mechanisms of the cyclization reaction. The crystal and molecular structures of clusters 5, 7, and 9 are presented.