Rhenium-Bismuth Carbonyl Cluster Compounds

The reaction of Re-2(CO)(8)[mu-eta(2)-C(H)=C(H)Bu-n](mu-H) with BiPh3 in heptane solvent at reflux yielded three new compounds Re-2(CO)(8)(mu-BiPh2)(2), 1 (14% yield), [Re(CO)(4)(mu-BiPh2)](3),2 (5% yield), and Re-2(eta(6)-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 center dot center dot center dot Re=4.483(1)angstrom. Compound 2 contains a six-membered Re3Bi3 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) angstrom. When compound 2 was heated to reflux in an octane solution, it was converted to two new compounds: cis-Re-4(CO)(16)-(mu-BiPh2)(2)(mu(4)-BiPhBiPh), cis-6 and trans-Re-4(CO)(16)(mu-BiPh2)(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 Re2Bi3 rings that share a qyadruply bridging BiPhBiPh ligand that contains a Bi-Bi bond; Bi-Bi=3.0237(7) angstrom in cis-6 and Bi-Bi=2.9765(3) angstrom 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-BiPh2)(2)-(mu-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.