Thermal Skeletal Rearrangement of a <i>n</i><i>ido</i>-Ruthenacyclopentadiene Complex Involving Reversible Rupture and Formation of a Ruthenium−Ruthenium Bond

Thermolysis of a triruthenium complex containing a nido-ruthenacyclopentadiene ligand {Cp*Ru(μ-H)}3(CHCMe-CRCH) (3a, R = H; 3b, R = Me, Cp* = η5-C5Me5) affords an open-form Ru3 cluster (Cp*Ru)2{Cp*Ru(CHCMe-CRCH)}(μ-H) (4a, R = H; 4b, R = Me) as a result of partial Ru−Ru bond cleavage. Re-formation of an Ru3 triangle accompanied with C−C bond cleavage of the C4 fragment was performed by prolonged heating of 4 to afford a μ3-methylidyne-μ3-diruthenaallyl complex (Cp*Ru)3(μ-H)(μ3-CH)(μ3-CRCMeCH) (5a, R = H; 5b, R = Me).