Alkylidene-Ruthenium-Tin Catalysts for the Formation of Fatty Nitriles and Esters via Cross-Metathesis of Plant Oil Derivatives

The reaction of SnCl 2 with the Ru−Cl bond of the Grubbs I catalyst RuCl 2 (═CHPh)(PCy 3 ) 2 ( 1 ) gives the complex {[Ru(═CHPh)(SnCl 3 )(PCy 3 )] 2 (μ-Cl) 3 } − [HPCy 3 ] + ( 2 ), but containing two diethyl ether solvate molecules. The formal insertion of SnCl 2 into one Ru−Cl bond of the Hoveyda II catalyst RuCl 2 (═CH-C 6 H 4 OPr i )(H 2 IMes) ( 3 ) (H 2 IMes = N, N ′-dimesityl-4,5-dihydroimidazol-2-ylidene) results in formation of the new complex RuCl(SnCl 3 )(═CH-C 6 H 4 OPr i )(H 2 IMes) ( 4 ). The X-ray analyses of 2 and 4 show the presence of very short Ru−Sn bonds (2.5834(9) Å mean bond for 2 and 2.5925(12) Å for 4 ) and the retention of short Ru═C bonds (1.895(10) and 1.825(8) Å, respectively). Complex 4 shows an excellent catalytic activity for the cross-metathesis of plant oil derivatives, the C11 ω-unsaturated ester and aldehyde and the unsaturated C18 diester with acrylonitrile, and a good activity for their cross-metathesis with methyl acrylate. Good to excellent yield of α,ω-bifunctional compounds, precursors of polyesters and polyamides, were obtained. Complex 2 shows catalytic activity for the self-metathesis of C11 ω-unsaturated aldehyde at low concentration to produce C20 α,ω-dialdehyde.