5-COORDINATE AND 6-COORDINATE BIS(ALKYNYL)RHODIUM(III) COMPLEXES CONTAINING A RH-SNPH(3) BOND

The reaction of [Rh(eta(2)-O(2)CMe)(PiPr(3))(2)] (I) with Ph(3)SnCr=CP h afforded, by elimination of Ph(3)-SnOAc, the five-coordinate complex [Rh(C=CPh)(2)(SnPh(3))-(PiPr(3))(2)] (2) in 75% yield. Treatment of 2 with excess PMe(3) gave the octahedral compound mer,trans-[Rh-(C=CPh) (2)(SnPh(3))(PMe(3))(3)] (3), the molecular structure of which has bee n determined. Compound 2 reacted with an equimolar amount of iodine to yield the rhodium(I) diyne complex trans-[RhI(eta(2)-PhC=CC=CPh)-(PiP r(3))(2)] (4), which could also be obtained from [RhCl-(PiPr(3))(2)](2 ), 1,4-diphenylbutadiyne, and NaI. The X-ray crystal structure analysi s of 4 confirmed the square-planar geometry around the rhodium center and the coordination of a bent, eta(2)-coordinated diyne ligand.