Ruthenium(0) complexes 1-4 containing 1,2,3,4-tetramethyl-5,6-bis(methylene)-l,3-cyclohexadiene (o-quinodimethane) are formed by abstraction of two protons from a q6-hexamethylbenzeneruthenium(lr) complex, the metal atom being coordinated to the exocyclic diene. 1, L = L' = P(OMe), 2, L = L' = P(OCH,),CMe 3, L = L' = PMe,Ph 4, L, = diphos; L' = PMe,Ph