[Rh(mu-OH)(PiPr(3))(2)](2): Versatile tool for the binding of alkynyl, diynyl, and diyndiyl ligands to an electron-rich rhodium(I) center

The reaction of [RhCl(PiPr(3))(2)](2) (1) with NaOH under phase-transfer conditions afforded the labile and extremely air-sensitive hydroxorhodium(I) complex [Rh(mu-OH)(PiPr(3))(2)](2) (2) in 80% yield. The X-ray crystal structure analysis of 2 confirmed the dimeric nature of-the molecule containing a nearly planar Rh2O2 unit. Compound 2 reacted with CO to yield trans-[Rh(OH)(CO)(PiPr(3))(2)] (4) and with PhC=CSiMe(3), in the presence of pyridine or CO, to give trans-[Rh(C=CPh)(py)(PiPr(3))(2)] (5) and trans-[Rh(C=CPh)(CO)(PiPr(3))(2)] (6), respectively, Treatment of 4 with Me(3)SiC=CC=CSiMe(3) yielded the binuclear diyndiyl complex [(PiPr(3))(2)(CO)Rh(C=CC=C)Rh(CO)(PiPr(3))(2)] (7), while the corresponding reaction of 4 with Me(3)SiC=CC=CSnPh(3) gave the mononuclear product trans-[Rh(C=CC=CSiMe(3))(CO)(PiPr(3))(2)] (8). The X-ray crystal structure analysis of 7 revealed the presence of an almost linear Rh-C-4-Rh linkage with the midpoint of the central C-C bond as a crystallographic center of symmetry.