TY - JOUR
T1 - The effect of counter ions on the far-infrared spectra of tris (triphenylphosphinegold) oxonium dimer salts
AU - Bennett, Trystan
AU - Falcinella, Alexander
AU - White, Reuben
AU - Adnan, Rohul
AU - Golovko, Vladimir
AU - Andersson, Gunther
AU - Metha, Gregory
PY - 2015
Y1 - 2015
N2 - Two tris(triphenylphosphinegold)oxonium dimer salts [{{Au(PPh3)}3(μ3-O)}2]2+(X-)2 (X = BF-4, MnO-4) were investigated via synchrotron-based far-infrared vibrational spectroscopy and density functional theory modelled at the M06/LANL2DZ level of theory. The 50-800 cm-1 region of both oxonium salts is presented, with the spectrum for [{{Au(PPh3)}3(μ3-O)}2]2+(BF-4)2 found to possess a large feature at 330.3 cm-1, attributable to counter-ion vibrational modes, which is only predicted upon explicit inclusion of counter-ions in the calculation. A feature around 107 cm-1 observed for the [{{Au(PPh3)}3(μ3-O)}2]2+(BF-4)2 infrared spectrum is assigned to 21 distinct vibrational modes arising from Au-Au bond stretching and other motions of the Au core. The same feature is predicted to be present within the [{{Au(PPh3)}3(μ3-O)}2]2+(MnO-4)2 spectrum but is masked by experimental noise. In the 50-400 cm-1 region, the relative intensities of predicted vibrational modes is found to depend heavily on the presence and nature of the counter-ions, while within the 400-800 cm-1 region, little dependence of the theoretical spectra on the type of counter-ion is predicted. Finally, the dimerization energies of both [{{Au(PPh3)}3(μ3-O)}2]2+(BF-4)2 and [{{Au(PPh3)}3(μ3-O)}2]2+(MnO-4)2 are calculated to be 3.06 eV and 3.20 eV, respectively, when the counter-ions are explicitly included within the calculation, and just 1.10 eV in their absence.
AB - Two tris(triphenylphosphinegold)oxonium dimer salts [{{Au(PPh3)}3(μ3-O)}2]2+(X-)2 (X = BF-4, MnO-4) were investigated via synchrotron-based far-infrared vibrational spectroscopy and density functional theory modelled at the M06/LANL2DZ level of theory. The 50-800 cm-1 region of both oxonium salts is presented, with the spectrum for [{{Au(PPh3)}3(μ3-O)}2]2+(BF-4)2 found to possess a large feature at 330.3 cm-1, attributable to counter-ion vibrational modes, which is only predicted upon explicit inclusion of counter-ions in the calculation. A feature around 107 cm-1 observed for the [{{Au(PPh3)}3(μ3-O)}2]2+(BF-4)2 infrared spectrum is assigned to 21 distinct vibrational modes arising from Au-Au bond stretching and other motions of the Au core. The same feature is predicted to be present within the [{{Au(PPh3)}3(μ3-O)}2]2+(MnO-4)2 spectrum but is masked by experimental noise. In the 50-400 cm-1 region, the relative intensities of predicted vibrational modes is found to depend heavily on the presence and nature of the counter-ions, while within the 400-800 cm-1 region, little dependence of the theoretical spectra on the type of counter-ion is predicted. Finally, the dimerization energies of both [{{Au(PPh3)}3(μ3-O)}2]2+(BF-4)2 and [{{Au(PPh3)}3(μ3-O)}2]2+(MnO-4)2 are calculated to be 3.06 eV and 3.20 eV, respectively, when the counter-ions are explicitly included within the calculation, and just 1.10 eV in their absence.
UR - http://www.scopus.com/inward/record.url?scp=84941243807&partnerID=8YFLogxK
U2 - 10.1039/c5ra11599j
DO - 10.1039/c5ra11599j
M3 - Article
SN - 2046-2069
VL - 5
SP - 74499
EP - 74505
JO - RSC Advances
JF - RSC Advances
IS - 91
ER -