The intra- and interionic structures of a mononuclear phosphine gold(I) alkyne complex [(PArF3)Au(2-hexyne)]BF4 [1BF4; ArF = 3,5-bis(trifluoromethyl)phenyl] and its analogous complex [(NHC)Au- (2-hexyne)]BF4 [2BF4; NHC = 1,3-bis(diisopropylphenyl)imidazol-2- ylidene] have been investigated by combining 1D and 2D multinuclear NMR spectroscopy and density functional theory calculations. It has been found that alkyne in 1BF4 is depleted of its electron density to a greater extent than that in 2BF4. This correlates with the Δδ(13C) NMR of the carbon-carbon triple bond. Instead, 2BF4 is much more “kinetically stable” than 1BF4. 19F-1H HOESY NMR experiments indicate that the counterion locates close to the gold atom in 1BF4 (differently from that previously observed in the few other gold(I) ion pairs studied), exactly where the computed Coulomb potential indicates that partial positive charge accumulates.
A Phosphine Gold(I) pi-Alkyne Complex: Tuning Metal-Alkyne Bond Character and Counterion Position by the Choice of the Ancillary Ligand
ZUCCACCIA, DANIELE;BELPASSI, LEONARDO;ROCCHIGIANI, LUCA;TARANTELLI, Francesco;MACCHIONI, Alceo
2010
Abstract
The intra- and interionic structures of a mononuclear phosphine gold(I) alkyne complex [(PArF3)Au(2-hexyne)]BF4 [1BF4; ArF = 3,5-bis(trifluoromethyl)phenyl] and its analogous complex [(NHC)Au- (2-hexyne)]BF4 [2BF4; NHC = 1,3-bis(diisopropylphenyl)imidazol-2- ylidene] have been investigated by combining 1D and 2D multinuclear NMR spectroscopy and density functional theory calculations. It has been found that alkyne in 1BF4 is depleted of its electron density to a greater extent than that in 2BF4. This correlates with the Δδ(13C) NMR of the carbon-carbon triple bond. Instead, 2BF4 is much more “kinetically stable” than 1BF4. 19F-1H HOESY NMR experiments indicate that the counterion locates close to the gold atom in 1BF4 (differently from that previously observed in the few other gold(I) ion pairs studied), exactly where the computed Coulomb potential indicates that partial positive charge accumulates.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
