The reaction of ReCl(2)L(2)(CO)(NO) (L = P(OMe)(3) (1a), PEt(3) (1b)) with excess silver trifluoromethanesulfonate (AgOTf) in boiling acetonitrile led to an isomeric mixture of [ReCl(CH3CN)(2)L(CO)(NO)][OTf] (L = P(OMe)(3) (2a) PEt(3) (2b)) (approximately 2:1 ratio) with the chloride ligands trans to CO or NO. The isomers of 2a and 2b could not be separated, except for a few yellow prisms of the trans Cl, NO compound of 2b, the structure of which was established by an X-ray diffraction study. The cation of 2b contains an octahedral Re atom bearing one phosphine ligand trans to one acetonitrile molecule (Re-N3 2.144(6) Angstrom). A second acetonitrile ligand (Re-N2 2.143(6) Angstrom) is located trans to the CO ligand (Re-Cl 1.928(8) Angstrom, C1-O2 1.142(10) Angstrom) and the chlorine substituent is arranged trans to the NO group (Re-N1 1.810(3) Angstrom, N1-O1 1.190(11) Angstrom). The Cl-Re-NO moiety was found to be positionally disordered. For further characterization of these isomers by chemical means, 2a and 2b were reacted with bpy to yield stable [ReCl(bpy)(CO)L(NO)][OTf] derivatives (L = P(OMe)(3) (3a), PEt(3) (3b)). The solid state IR spectrum supports the assumption that the isomers of 3a and 3b co-crystallize in the same crystal framework. This apparently prevented separation by crystallization. The reaction of 1 with 1 or 2 equiv of AgOTf in boiling toluene allowed the preparation of the mono- and disubstituted complexes ReCl(OTf)L(2)(CO)(NO) (L = P(OMe)(3) (4a), PEt(3) (4b)) and Re(OTf)(2)L(2)(CO)(NO) (L = P(OMe)(3) (5a), PEt(3) (5b)). The replacement of the triflate ligands in 5a and 5b by acetonitrile are slow reactions (approximately 5d for 5a and 15h for 5b at room temperature), which proceed with retention of the geometry.