Investigating the 197Au-31P spin-spin coupling interactions in gold-phosphine halides using solid-state nuclear magnetic resonance, spectral simulations, and quantum chemistry computations

Abstract

Phosphorus-31 nuclear magnetic resonance spectroscopy with magic angle spinning was used to characterize 197Au-31P spin-spin coupling interactions in solid gold-phosphine halides and the spectra have been analyzed using perturbation theory. The 197Au nucleus has a natural abundance of 100%, a spin of 3/2, and one of the smallest nuclear magnetic moments of all spin-active nuclei. Gold-197 has a very large nuclear quadrupole moment that leads to 197Au nuclear quadrupolar coupling constants of approximately 1 GHz, and thus the Zeeman interaction for 197Au is a perturbation on the quadrupolar interaction. The indirect spin-spin coupling constants, 1J(197Au,31P), extracted from our experiments are compared with those calculated using quantum chemistry computations. The calculations show that the Fermi-contact mechanism is the most important spin-spin coupling mechanism. Anisotropy in the 197Au-31P spin-spin coupling was shown to arise from the spin-dipolar Fermi-contact cross-term, and that its magnitude is on the same order as 1J(197Au,31P)iso.