Addition of ethyl diazoacetate to the allenylidene ligand of [Ru(η5-C5H5)(CCCPh2)(CO)(PPri3)]BF4: Synthesis of ruthenium organometallic compounds containing new cyclic unsaturated η1-carbon ligands

Abstract

The allenylidene complex [Ru(η5-C5H5)(CdCdCPh2)(CO)(PPri3)]BF4 (1) reacts with ethyl diazoacetate to give the cyclic carbene derivative [Ru(η5-C5H5){dCCHdC(OEt)OCdCPh2}-(CO)(PPri3)]BF4 (2). The structure of 2 was determined by an X-ray investigation, revealing a Ru-C distance of 2.017(6) Å. Treatment of 2 with sodium methoxide and methyllithium gives rise to the derivatives Ru(η5-C5H5){CdCHC(R)(OEt)OCdCPh2}(CO)(PPri3) (R ) OMe (3), Me (4)). When a tetrahydrofuran solution of 3 is passed through an Al2O3 column, the lactonyl complex Ru(η5-C5H5){CdCHC(O)OCdCPh2}(CO)(PPri3) (5) is obtained. Complex 3 reacts with HBF4‚OEt2 to regenerate 2 by selective elimination of methanol. The protonation of 4 with HBF4‚OEt2 produces the elimination of ethanol and the formation of [Ru(η5-C5H5)-{)CCHdC(CH3)OC)CPh2}(CO)(PPri3)]BF4 (6). The structure of 6 was also determined by an X-ray investigation, revealing a Ru-C distance of 2.010(6) Å. The related cyclic carbene compound [Ru(η5-C5H5){dCCHdC(OH)OCdCPh2}(CO)(PPri3)]BF4 (7) has been prepared by reaction of 5 with HBF4‚OEt2.