The new nitrosyl carbonylmetalate PPN[Cr(CO)4(NO)] has been synthesized from Cr(CO)6 and PPN(NO2) in THF (PPN = bis(triphenylphosphine)iminium cation). The material was characterized by infrared and 15N NMR spectroscopy and by elemental analysis, which demonstrated it has the same structure as Mn(CO)4(NO). Kinetic experiments show the reaction to be first order in both chromium and nitrite with k = 0.25 ± 0.05 M-1 sec-1 at 58.60 ± 0.05°C. A mechanism consistent with this and related results is discussed. Metalcarbon, metalhydrogen, and metalmetal bonds have been formed by the reactions of PPN[Cr(CO)4(NO)] with eletrophiles (CF3SO3CH3, CF3SO3H, Ph3SnCl). With the labile complexes, M(CO)5(THF) (M = Cr, Mo and W), PPN[Cr(CO)4(NO)] produces the homo- and hetero-dinuclear complexes PPN[CrM(CO)9(NO)] (M = Cr, Mo and W).