Synthesis and molecular structures of the cationic gold(I)–aziridine complexes [Ph3PAuAz]O3SCF3 (Az = C2H4NH, CH2CHMeNH, CH2CMe2NH, CH2CHEtNH, CH2CHPhNH, C2H4NBz, C2H4NC2H4OH)

The gold(I) complex Ph3PAuCl (1) reacts in the presence of AgO3SCF3 (=AgOTf) with a series of aziridines with various NH-, NR-, CHR- and CR2-functionalities via halide elimination at ambient temperature, to give the cationic mixed phosphane-aziridine gold(I) complexes [Ph3PAuAz]OTf (2–8) (Az = aziridine, 2-methylaziridine, 2,2-dimethylaziridine, 2-ethylaziridine 2-phenylaziridine, N-benzylaziridine, N-hydroxyethylaziridine). The X-ray structure analyses show the gold(I) centres are linearly coordinated by the PPh3 and Az ligands, and the intact three membered aziridine rings coordinate through the distorted tetrahedral N-atoms. Compounds 2–8 are stable with respect to both directed thermal or photolytic alkene elimination, or any ring N–C opening reaction which would result in the corresponding cationic nitrene complexes [Ph3PAuNH]OTf and [Ph3PAuNR]OTf, or any oxidative addition products. The phenyl substituent in the 2-position of 6 is obviously bowed with its plane towards the Au centre, indicating some Au–π-ring interaction with the distance Au–Cn ≈ 4.00 Å. The O atom of the hydroxy group in 8 also lies very close to the Au centre, with the distance Au–O = 3.078 Å. The IR, 1H, 13C and 31P NMR, and MS spectra are reported and discussed, and the molecular structures of 3, 4, 6 and 8 have been determined by single crystal X-ray diffraction analyses.