The synthesis of [FeRu(CO)2(μ-CO)2(η-C5H5)(η-C5Me5)] and convenient entries to its organometallic chemistry

The synthesis, fluxionality and reactivity of the heterobimetallic complex [FeRu(CO)(2)(mu-CO)(2)(eta-C5H5)(eta-C5Me5)] ( 5) are described. Complex 5 exhibits enhanced photolytic reactivity towards alkynes compared to its homometallic analogues, forming the dimetallacyclopentenone complexes [FeRu(CO)(mu-CO){mu-eta(1):eta(3)-C(O) CR"CR'}(eta-C5H5)( eta-C5Me5)] (9, R' = R" = H; 10, R' = R" = CO2Me; 11, R' = H, R" = CMe2OH). Prolonged photolysis with diphenylethyne gives the dimetallatetrahedrane complex [FeRu(mu-CO)(mu-eta(2):eta(2)-CPhCPh)(eta-C5H5)(eta-C5Me5)] ( 17), which contains the first iron-ruthenium double bond. Complexes containing a number of organic fragments can be synthesised using 9, 10 and 11. Heating a solution of 10 gave the alkenylidene complex [FeRu(CO)(2)(mu-CO){mu-eta(1):eta(1)C= C(CO2Me)(2)}(eta-C5H5)(eta-C5Me5)] (23) through an unusual methylcarboxylate migration. Protonation and then addition of hydride to 9 gives the ethylidene complex [FeRu(CO)(2)(mu-CO)(mu-CHCH3)(eta-C5H5)(eta-C5Me5)] (27) via the ionic vinyl species [FeRu(CO)(2)(mu-CO)(mu-eta(1):eta(2)-CH=CH2)(eta-C5H5)(eta-C5Me5)][BF4] ( 25). Compound 25 exhibits cis/trans isomerisation at room temperature. Protonation of 11 gives the allenyl species [FeRu(CO)(2)(mu-CO)(mu-eta(1):eta(2)CH= C=CMe2)(eta-C5H5)(eta-C5Me5)][BF4] ( 30). Compound 30 exist as three isomers, two cis and one trans. The two cis isomers are shown to be interconverting by sigma-pi isomerisation. The solid state structures of 5, 11, 12, 17, 23, 25 and 30 were established by X-ray crystallography and are discussed.