SYNTHESIS OF NEW BUTADIENE-OSMIUM(0) AND BUTADIENE-RUTHENIUM(0) COMPLEXES BY REDUCTIVE CARBON-CARBON COUPLING OF 2 ALKENYL FRAGMENTS

The five-coordinate complexes Os{(E)-CH=CHR}Cl(CO)(PiPr(3))(2) (R = Ph (3), H (6)) react with CH2=CHMgBr to give the osmium(0) derivatives Os(eta(4)-C(4)H(5)R)(CO)(PiPr(3))(2) (R = Ph (5), H (7)). The molecular structure of 5 has been determined by X-ray crystallography. The coordination around the osmium atom can be described as a distorted square pyramid with a triisopropylphosphine ligand located at the apex. The base is formed by the carbonyl group and the other triisopropylphosphine ligand mutually cis disposed and by the midpoints of both terminal carbon-carbon bonds of the diene. The reaction of the chloro-styryl-ruthenium(II) complex Ru{(E)-CH=CHPh}Cl(CO)(PiPr(3))(2) (4) with CH2=CHMgBr leads to Ru{(E)-CH=CHPh}(CH=CH2)(CO)(PiPr(3))(2) (10), which affords Ru(eta(4)-C(4)R(5)Ph)(CO)(PiPr(3))(2) (11) by stirring in hexane at 50 degrees C. 10 reacts with carbon monoxide to give Ru{(E)-CH=CHPh}(CH=CH2)(Co)(2)(PiPr(3))(2) (12), which can be also prepared by reaction of Ru{(E)-CH=CHPh}Cl(CO)(2)(PiPr(3))(2) (13) with CH2=CHMgBr.