text: Compounds derived from various transition metal carbonyl complexes are organometallic representatives with somewhat unusual cyclic structure and electronics. Such a representative is given in the form of the paramagnetic, ten-electron, tetrahedral  [CpCo][Bi{Co(CO)}] complex.
  Additionally, clusters like closo-[BiCr(CO)] and [BiMo(CO)] have been reported to stabilize the ozone-like structure of [Bi]. The [Bi] species, isostructural and isoelectronic with ozone, can be analyzed independently as a moiety bound to the metal carbonyl complexes. The reported Bi-Bi distance falls in between the single and double bond region and is elongated compared to Bi=Bi bond in the [Bi] cluster, the later displaying a bond order of 1.25. This experimental observation is being rationalized by some amount of π-donation to the metal carbonyl center and simultaneously π* back-bonding to the bismuth cluster from the metallocene complex.
  In 2009, Pearl et al. described the synthesis and isomerization of heterometallic complexes containing bismuth and rhenium. The precursors used in synthesis were an alkene-coordinated carbonyl rhenium complex and BiPh. The reaction yields two types of heteronuclear bismuth-rhenium complexes and a homodinuclear rhenium one as a side product. Upon heating, the hexametallic tribismuth-trirhenium heteronuclear complex undergoes isomerization to cis- and trans-clusters containing the bicyclo [3.3.0] core (see scheme below). Under subsequent irradiation both stereoisomers convert to a common spiro [4.3] cluster compound.