Five new compounds were obtained from the reaction of Os-3(CO)(11)(NCMe), 1, with BiPh3 in hexane solution at reflux. These have been identified as Os-2(CO)(8)(mu-BiPh), 2, Os(CO)(4)Ph-2, 3, Os-4(CO)(14)(mu-eta(3)-O=CC6H5)(mu(4)-Bi), 4, Os-4(CO)(15)-Ph(mu(4)-Bi), 5, and Os-5(CO)(19)Ph(mu(4)-Bi), 6. Cleavage of the phenyl groups from the BiPh3 was the dominant reaction pathway. Fragmentation of the original triosmium cluster was accompanied by reaggregation processes that were facilitated by the naked bismuth to yield the higher nuclearity osmium cluster complexes containing spiro-bridging bismuth ligands. Compound 6 was photo-decarbonylated to yield the compound HOs5(CO)(18)(mu-eta(2)-C6H4)(mu(4)-Bi), 7, formed by ortho-CH activation of the sigma-bonded phenyl ring in 6 to form a bridging eta(2)-benzyne ligand. Compounds 2-7 were each characterized structurally by a single-crystal X-ray diffraction analysis.