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))

Reactions of [H2Os3(CO)10] with a series of diynes, RC2C2R‘ (1: R = Ph, R‘ = CH2OH; 2: R = Ph, R‘ = C(O)Ph; 3: R = R‘ = C(OH)Me2), 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 [HOs3(CO)10{μ-η1:η2-PhCH2(CCH−CCH−O)}] (5) and [HOs3(CO)10{μ-η1:η1-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 [HOs3(CO)9(μ3-η1:η3:η1-Ph(CCH−CC−O)CPh)] (7) with a closed “C3Os3” pentagonal pyramidal structure. Reaction of [H2Os3(CO)10] with 3 does not lead to cyclization of the diyne; instead, the clusters [Os3(CO)10{μ3-η2-(RCHCH−C2R)}] (8) and [Os3(CO)10{μ3-η2-(RC2C2R)}] (9) are formed. Deuterium labeling of the starting compounds has been used in the reaction of [H2Os3(CO)10] with HOCH2C2C2CH2OH in order to investigate possible mechanisms of the cyclization reaction. The crystal and molecular structures of clusters 5, 7, and 9 are presented.