Rhenium−Bismuth Carbonyl Cluster Compounds

The reaction of Re2(CO)8[μ-η2-C(H)C(H)Bun](μ-H) with BiPh3 in heptane solvent at reflux yielded three new compounds Re2(CO)8(μ-BiPh2)2, 1 (14% yield), [Re(CO)4(μ-BiPh2)]3, 2 (5% yield), and Re2(η6-C6H5Ph)(CO)7, 3, 4.7 mg (7% yield). Compound 1 contains two Re(CO)4 groups joined by two bridging BiPh2 ligands in a four-membered ring. There is no Re−Re bond in 1, Re···Re = 4.483(1) Å. Compound 2 contains a six-membered Re3Bi3 ring in a twist-boat conformation. When heated to 110 °C in toluene, compound 1 was transformed into the heterocycle 2 (8% yield), the known compound Re(CO)5Ph, 4 (25% yield), and the new compound Re2(CO)8(μ-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) Å. When compound 2 was heated to reflux in an octane solution, it was converted to two new compounds: cis-Re4(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), cis-6 and trans-Re4(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), trans-7 and a small amount of 1 (3% yield). cis-6 and trans-7 are isomers. Both compounds contain two fused Re2Bi3 rings that share a quadruply bridging BiPhBiPh ligand that contains a Bi−Bi bond; Bi−Bi = 3.0237(7) Å in cis-6 and Bi−Bi = 2.9765(3) Å 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 Re4(CO)16(μ-BiPh2)2(μ-BiBiPh2), 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 Re2Bi3 ring, and one four-membered Re2Bi2 ring.