期刊
MAGNETIC RESONANCE IN CHEMISTRY
卷 45, 期 11, 页码 917-924出版社
JOHN WILEY & SONS LTD
DOI: 10.1002/mrc.2075
关键词
NMR; C-13; P-31; solid state; CP/MAS; aurophilic contact; nuclear overhauser effect; signal doubling; AA ' BB ' spin; helical conformation
Variable-temperature solution H-1- and P-31-NMR experiments are reported for [Au-2(xantphos)(2)](NO3)(2) gold(I) complex incorporating a 16-membered Au2P4C8O2 macrocycle derived from the 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (xantphos) ligand. These NMR studies provide detailed structural information about its solution structure in comparison to the solid-state structure available from single crystal X-ray diffraction. Two-dimensional H-1-NOESY spectroscopy at low temperatures allowed the full assignment of proton resonances, which are severely exchange-broadened at room temperature. The H-1-H-1 spatial connectivities of the large number of non-equivalent protons unravel the complete stereochemistry of the gold(I) macrocycle in its symmetrically twisted conformation. Chemical exchange between particular proton pairs has allowed understanding the molecular dynamics and ruled out formation of coordination oligomers. Spectral analysis of the unique phosphorous AA'BB' spin system has revealed three-bond P-31-P-31 scalar couplings mediated through the Au...Au bond, and has confirmed the existence of the aurophilic contact in low-temperature solutions. The solution C-13 and P-31 spectra are compared to the solid state P-31-MAS and C-13-CP/MAS spectra, where signal doubling effects due to the crystal packing have been discovered. Copyright (c) 2007 John Wiley & Sons, Ltd.
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