Velasquez J, Njegic B, Gordon M S, Duncan M A
Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
J Phys Chem A. 2008 Mar 6;112(9):1907-13. doi: 10.1021/jp711099u. Epub 2008 Feb 12.
Au+(CO)n complexes are produced in the gas phase via pulsed laser vaporization, expanded in a supersonic jet, and detected with a reflectron time-of-flight mass spectrometer. Complexes up to n = 12 are observed, with mass channels corresponding to the n = 2 and n = 4 showing enhanced intensity. To investigate coordination and structure, individual complexes are mass-selected and probed with infrared photodissociation spectroscopy. Spectra in the carbonyl stretching region are measured for the n = 3-7 species, but no photodissociation is observed for n = 1, 2 due to the strong metal cation-ligand binding. The carbonyl stretch in these systems is blue-shifted 50-100 cm-1 with respect to the free CO vibration (2143 cm-1), providing evidence that these species are so-called "nonclassical" metal carbonyls. Theory at the MP2 and CCSD(T) levels provides structures for these complexes and predicted spectra to compare to the experiment. Excellent agreement is obtained between experiment and theory, establishing that the n = 3 complex is trigonal planar and the n = 4 complex is tetrahedral.
通过脉冲激光汽化在气相中产生Au+(CO)n配合物，在超声速喷流中膨胀，并使用反射式飞行时间质谱仪进行检测。观察到n值高达12的配合物，对应于n = 2和n = 4的质量通道显示出增强的强度。为了研究配位和结构，对单个配合物进行质量选择并用红外光解离光谱进行探测。测量了n = 3 - 7物种在羰基伸缩区域的光谱，但由于金属阳离子与配体的强结合，未观察到n = 1、2的光解离。相对于自由CO振动（2143 cm-1），这些体系中的羰基伸缩发生了50 - 100 cm-1的蓝移，这证明这些物种是所谓的“非经典”金属羰基化合物。MP2和CCSD(T)水平的理论为这些配合物提供了结构，并预测了光谱以与实验进行比较。实验与理论之间取得了极好的一致性，确定n = 3的配合物为三角平面结构，n = 4的配合物为四面体结构。
