Chemistry of highly electrophilic binuclear cations. 6. Synthesis of the alkyne-bridged complexes [Mo2(η5-C5H5)2{μ-η2:η2-HC2(p-tol)}(CO)2(μ-L2)][B{3,5-C6H3(CF3)2}4]2 and their isocyanide derivatives (L2 = Ph2PCH2PPh2, Me2PCH2PMe2)

One-electron oxidation of the alkyne-bridged radical cations [Mo2Cp2{μ-η2:η2-HC2(p-tol)}(CO)2(μ-A2PCH2PA2)] (A = Ph, Me) gives the 32-electron cations [Mo2Cp2{μ-η2:η2- HC2(p-tol)}(CO)2(μ-A2PCH2PA2)]2+ which display two isomers differing in the relative position (cis or trans) of the alkyne and diphosphine bridges. Displacement of CO by CNtBu (L) occurs readily in the latter to give only cis derivatives.