Formation of the trans-[dioxorhenium(1+)] group from the reactions of ReNCl2(PPh3)2, ReCl4(PPh3)2, and ReCl3(CH3CN)(PPh3)2 with chelating amines and tetraazamacrocycles. Crystal structure of trans-[ReO2(cyclam)](PF6) (cyclam = 1,4,8,11-tetraazacyclotetradecane)

The complexes ReNCl2(PPh3)2 (1), ReCl4(PPh3)2 (2), and ReCl3(CH3CN)(PPh3)2 (3) react with bidentate (L2) and tetradentate (L1) chelating amines and with 1,4,8,11-tetraazacyclotetradecane (cyclam) at room temperature, to afford cationic trans-dioxorhenium(V) complexes of the type [ReO2(L(n))n]+ (n = 1, 2) and [ReO2(cyclam)]+ (4). These reactions constitute an unexpected alternative route to the synthesis of rhenium(V) complexes containing the trans-[ReO2]+ group. The complex cation 4 was isolated with three different counterions (ReO4-, Cl-, PF6-). The perrhenate and chloride salts, 4(ReO4) and 4(Cl), show a single infrared absorption at 772 cm-1, assigned to the asymmetric stretching vibration of the trans-[ReO2]+ group, while the hexafluorophosphate salt, 4(PF6), shows two absorptions at 809 and 776 cm-1, assigned to the same vibration. This fact has been attributed to the presence of two symmetry-inequivalent molecules of the cation 4 in the solid-state structure of 4(PF6), which has been determined by X-ray crystallography. Complex cation 4 is monomeric and has an approximately octahedral arrangement of ligands around the rhenium atom. The crystal structure consists of two independent cations and anions, and each ion has a crystallographically imposed symmetry center. 4(PF6) crystallizes in the triclinic space group P1BAR with cell parameters a = 5.533 (1) angstrom, b = 11.899 (3) angstrom, c = 13.622 (3) angstrom, V = 853.2 (4) angstrom3, Z = 2, R = 0.063, and R(w) = 0.081 for 3006 observed reflections.