The current literature on multiply bonded dirhenium complexes that contain the bis(dimethylphosphino)methane ligand (abbreviated dmpm) is reviewed. New procedures are described for the synthesis of the complex Re,Cl&dmpm),. The analogous bromide and iodide complexes of stoichiometry Re&(~-dmpm)3 have been prepared by the reactions of Re,Br&-dppm), (dppm = PhzPCHzPPh z and Re&(PR,), (X=Br or I; R =Et or Pr") with ) dmpm. The reactions of Re&&-dmpm), (X = Cl or Br) with NOPF, in dichloromethane give the paramagnetic species [Re,X&-dmpm),]PF+ The chloro complex reacts further with NOPFs to afford the diamagnetic complex Re,Cl,(p-dmpm),(NO). This is the first triply bonded dimetal complex that contains a nitrosyl ligand and is stabilized to fission of the metal-metal bond. The identity of this complex has been confirmed by a single crystal X-ray structure determination. Crystal data at 20 "C: orthorhombic space group Zba2 (No. 45), a =14.278(3), b = 23.966(3), c = 13.880(3) A, V= 4749(3) A, Z = 8. The structure was refined by full matrix least-squares to R =0.036 (R,=O.O47) for 1427 data with Z> 30(Z). The structure, which can be represented as Cl,Re(pdmpm),ReCl,(NO), contains a terminally bound NO ligand and a cis, trans disposition of the pairs of phosphorus donor atoms at the two metal centers. The Re-Re bond distance is 2.379(l) A.