Reactions of Dihydrido(bicarbonato)bis(triisopropylphosphine)rhodium(III) with Alkynes. Formation of Rh2H2(O2CO)(PhCCPh)(P(i-Pr)3)3 and the Stereoselective Hydrogenation of Alkynes to Trans Olefins

Article abstract of DOI:10.1021/ja00358a015

A recation of RhH2(O2COH)(P(i-Pr)3)2 (1) with PhC<*>CPh has been found to give trans-stilbene and a novel binuclear rhodium complex Rh2H2(O2CO)(PhC<*>CPh)(P(i-Pr)3)3 (2).A similar reaction with MeO2CC<*>CCO2Me results both in H2 evolution and half-hydrogenation, while with F3CC<*>CCF3 only H2 evolution is observed.Compound 1 catalyzes the stereoselective half-hydrogenation of alkynes to trans olefins.Complex 2 crystallizes in the monoclinic space group C⁵_2h-P2₁/c, with four formula units in a cell of dimensions a = 17.158 (4) Angstroem, b = 23.916 (3) Angstroem, c = 11.255 (3) Angstroem, β = 103.3 (1) deg, and V = 4494 Angstroem³ (t ca. -160 deg C).In the solid state 2 consists of a distorted octahedral Rh(III) center and a distorted square-planar Rh(I) center bridged by a bis-bidentate carbonato group.