A series of benzobisimidazolium salts 1a–d has been prepared by tetraalkylation of benzobisimidazol. The salts 1a–d react with two equivalents of [Pt(Cl)₂dppe] in the presence of 2.2 equivalents of sodium acetate to yield the dinuclear biscarbene complexes 2a–d. Under the same reaction conditions, the benzobisimidazolium salts react with only one equivalent of [Pt(Cl)₂dppe] and one equivalent of sodium acetate to yield the monometalated carbene/benzimidazolium derivatives 3a,3c. Benzobisimidazolium salt 1c reacts with two equivalents of nickelocene to give the biscarbene bridged dinuclear nickel complex 4. Treatment of 4 with two equivalents of 4,4′-bipyridine leads to the formation of the CpNi^II-cornered molecular rectangle 5.