Structural, Theoretical and Spectroscopic Characterisation of a Series of Novel Gold(I)-Norbornene Complexes Supported by Phenanthrolines: Effects of the Supporting Ligand

A series of novel gold(I) alkene complexes of general formula [Au(N^N)(η2-nb)][PF6] [N^N = PHEN (1,10-phenanthroline), NCP (2,9-dimethyl-1,10-phenanthroline), 4,7-DMP (4,7-dimethyl-1,10-phenanthroline), TMP (3,4,7,8-tetramethyl-1,10-phenanthroline), BTP (4,7-diphenyl-1,10-phenanthroline) and BTC (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline); nb = norbornene] were synthesized by a novel synthetic pathway. The novel cationic gold(I)-norbornene complexes were fully characterized by 1H and 13C NMR spectroscopy and the crystal structure of three complexes was solved by single-crystal X-ray diffraction. The correlations between the nature and position of the substituents on the ancillary ligand and the spectroscopic and structural data highlight variations on the nature of the bonding. The combination of experimental and DFT data allowed to evaluate the extent of σ-donation and π back-donation in the bond with the olefin, suggesting that a fine interplay between electronic and steric effects on the ancillary ligand can affect the bond properties and structural features of the complexes.