The reaction of ethynylferrocene with Cp*Rh half-sandwich complexes containing a chelating 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolato ligand, Cp*Rh[E2C2(B10H10)], E=S, Se

Dimerisation of ethynylferrocene (2) to give a mixture of (E)- and (Z)-1,4-diferrocenylbuten-3-yne (ratio=1:1) takes place in boiling chloroform if the 16e half-sandwich complex Cp*Rh[Se2C2(B10H10)] (1Se) is present. Under these conditions cyclo-trimerisation was not observed. In contrast, Cp*Rh[S2C2(B10H10)] (1S) reacts with 2 in a 1:1 ratio by insertion into one of the Rh–S bonds, followed by B–H activation, transfer of a hydrogen atom to carbon via rhodium and formation of a Rh–B bond to give 7S which was characterised by an X-ray structural analysis.