The dppm-bridged heterobimetallic μ-carbonyl complexes [(OC) 4M(μ-CO)(μ-dppm)Pt(PPh 3)] ( 1a, M=Cr; 1b, M=Mo; 1c, M=W) have been prepared by the reaction of [M(CO) 5(η 1-dppm)] (M=Cr, Mo, W) with [Pt(CH 2CH 2)(PPh 3) 2]. The outcome of stoichiometric isocyanide addition to 1 is electronically controlled by the π-accepting propensity of CNR. Addition of isocyanide ligands with strongly electron withdrawing substituents R affords the isonitrile-bridged complexes [(OC) 4M(μ-CN–R)(μ-dppm)Pt(PPh 3)] 2 (M=W; R=CF 3), 3 ( 3a, M=Cr; 3b M=Mo, 3c M=W; R=CH 2SO 2 p-tolyl), and 4 (M=W; R=[CH 2PPh 3][PF 6]. With less π-accepting isocyanides (R=CH 2Ph, C 6H 11, CH 2PO(OEt) 2,) the labile complexes [(RNC)(OC) 3W(μ-CO)(μ-dppm)Pt(PPh 3)] ( 5–7) ligated by a terminal isonitrile ligand are formed. In contrast, treatment of [(OC) 3Fe(μ-CO)(μ-dppm)Pt(PPh 3)] with CNCH 2PO(OEt) 2 yields exclusively [(OC) 3Fe{μ-CNCH 2PO(OEt) 2}(μ-dppm)Pt(PPh 3)] ( 9) with the isocyanide ligand in a bridging bonding mode. Upon protonation of 2 and 3b with HBF 4, the stable μ-aminocarbyne complexes [(OC) 4M(μ-CN(H)R′)(μ-dppm)Pt(PPh 3)][BF 4] ( 10–11) are formed by electrophilic addition of H + on the basic isonitrile nitrogen atom. The molecular structures of 1a, c, 2 and 3c have been determined by X-ray diffraction methods. The μ-CO and the μ-CNR ligands bridge the metal centres in an asymmetric manner, the Pt–μ-C distances being significantly shorter than the corresponding M–μ-C distances. In contrast, the μ-CNCH 2PO(OEt) 2 ligand of [(OC) 3Fe{μ-CN–CH 2PO(OEt) 2}(μ-dppm)Pt(PPh 3)] ( 9) bridges symmetrically the two metal centres. Furthermore, the molecular structure of cis-[(benzylNC)(OC) 4W(η 1-dppm)] ( 8a) resulting from degradation of 5 has been determined.