Rhenium-bismuth carbonyl cluster compounds.
The reaction of Re(2)(CO)(8)[mu-eta(2)-C(H)=C(H)Bu(n)](mu-H) with BiPh(3) in heptane solvent at reflux yielded three new compounds Re(2)(CO)(8)(mu-BiPh(2))(2), 1 (14% yield), [Re(CO)(4)(mu-BiPh(2))](3), 2 (5% yield), and Re(2)(eta(6)-C(6)H(5)Ph)(CO)(7), 3, 4.7 mg (7% yield). Compound 1 contains two Re(CO)(4) groups joined by two bridging BiPh(2) ligands in a four-membered ring. There is no Re-Re bond in 1, Re...Re = 4.483(1) A. Compound 2 contains a six-membered Re(3)Bi(3) ring in a twist-boat conformation. When heated to 110 degrees C in toluene, compound 1 was transformed into the heterocycle 2 (8% yield), the known compound Re(CO)(5)Ph, 4 (25% yield), and the new compound Re(2)(CO)(8)(mu-BiPh)(2), 5 (4% yield). Compound 5 contains two Re(CO)(4) groups joined by two bridging BiPh ligands and a Re-Re bond, Re-Re = 3.1006(18) A. When compound 2 was heated to reflux in an octane solution, it was converted to two new compounds: cis-Re(4)(CO)(16)(mu-BiPh(2))(2)(mu(4)-BiPhBiPh), cis-6 and trans-Re(4)(CO)(16)(mu-BiPh(2))(2)(mu(4)-BiPhBiPh), trans-7 and a small amount of 1 (3% yield). cis-6 and trans-7 are isomers. Both compounds contain two fused Re(2)Bi(3) rings that share a quadruply bridging BiPhBiPh ligand that contains a Bi-Bi bond; Bi-Bi = 3.0237(7) A in cis-6 and Bi-Bi = 2.9765(3) A in trans-7. The phenyl groups on the bridging BiPhBiPh ligand in cis-6 have a cis-orientation and in trans-7 they have a trans-orientation. In the presence of visible light, cis-6 and trans-7 are transformed into yet another isomer Re(4)(CO)(16)(mu-BiPh(2))(2)(mu-BiBiPh(2)), 8, by a shift of one of the phenyl ligands on the bridging BiPhBiPh ligand to the neighboring bismuth atom. Compound 8 contains two fused rings, one five-membered Re(2)Bi(3) ring, and one four-membered Re(2)Bi(2) ring.
Adams
Richard D
RD
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA. adams@mail.chem.sc.edu
Pearl
William C
WC