Reversible C−C Bond Cleavage and Interconversion of the Resulting Hydrocarbyl Ligands on Butterfly Frameworks Derived from Acetylide Complexes Cp*WOs3(μ4-CCR)(CO)11(R = Ph,nBu, CH2OMe, CH2OPh)

Abstract

Combination of mononuclear complexes Cp*W(CO)3(CCR) (Cp* = C5Me5; R = Ph, nBu, CH2OMe, CH2OPh) with the triosmium cluster Os3(CO)10(NCMe)2 in toluene affords two isomeric acetylide cluster compounds a and b, which possess the formula Cp*WOs3(CCR)(CO)11 (R = Ph (1), nBu (2), CH2OMe (3), CH2OPh (4)). Isomers a and b undergo reversible interconversion by relocating the Cp*W(CO)2 fragment between the hinge and wingtip positions upon heating in solution. Their reactivities vs the substituents on the acetylide ligand are also investigated and compared. Thus, thermolysis of 1a furnishes the carbido−alkylidyne cluster Cp*WOs3(μ4-C)(μ-CPh)(CO)10 (5) through reversible scission of the C−C bond induced by elimination of CO. By contrast, heating of 2 or 3 gives an isomeric mixture of the carbido−vinylidene clusters Cp*WOs3(μ4-C)(μ-H)(μ-CCHR‘)(CO)9 (R‘ = nPr (6), OMe (7)) through a subsequent C−H activation. The CH2OPh isomers 4 readily eliminate two CO ligands to give two isomeric carbido−benzofuryl clusters Cp*WOs3(...