Structure of a cis-dimetalla-alkene complex formed by the reaction of a ruthenium(II) complex with bis(phenylethynyl)mercury(II)

Abstract

X-Ray investigation of the product of the reaction of trans-[Ru(CO)₂Cl₂(PMe₂Ph)₂] with Hg(CCPh)₂shows it to be [Ru(CO)₂{C(CCPh)C(Ph)HgCl}Cl(PMe₂Ph)₂]. The proposed mechanism involves formation on the ruthenium of 1,4-diphenylbuta-1,3-diyne, and cis addition of an Ru–HgCl bond across one of the triple bonds of the diyne. The mass spectrum of the complex indicates that this addition is reversed on heating, with release of the diyne. The related complex [Ru(CO)₂{C(CCCMe₃)C(CMe₃)HgCl}Cl(PMe₂Ph)₂], prepared in the same way, decomposes slowly in solution even at room temperature, with release of Me₃CCC-CCCMe₃ and deposition of mercury.