Brathwaite A D, Abbott-Lyon H L, Duncan M A
College of Science and Mathematics, University of the Virgin Islands , St. Thomas, United States Virgin Islands 00802.
Department of Chemistry & Biochemistry, Kennesaw State University , Kennesaw, Georgia 30144, United States.
J Phys Chem A. 2016 Oct 6;120(39):7659-7670. doi: 10.1021/acs.jpca.6b07749. Epub 2016 Sep 23.
Carbonyl and nitrogen complexes with Rh are produced in a molecular beam using laser ablation and a pulsed-nozzle source. Mass-selected ions of the form Rh(CO) and Rh(N) are investigated via infrared laser photodissociation spectroscopy. The fragmentation patterns and infrared spectra provide information on the coordination and geometries of these complexes. The shifts in vibrational frequencies relative to the uncoordinated ligands give insight into the nature of the bonding interactions involved. Experimental band positions and intensities are compared to those predicted by density functional theory (DFT). Rh coordinates only four nitrogen molecules, whereas it can accommodate five carbonyl ligands. The fifth CO ligand resides in an axial site with bonding intermediate between coordination and solvation. The carbonyl stretch in Rh(CO) (2160 cm) is blue-shifted with respect to the molecular CO vibration (2143 cm). Conversely, the N-N stretch in Rh(N) (2297 cm) is red-shifted with respect to the free N vibration (2330 cm). The opposite directions of these frequency shifts is explained by a combination of σ donation and electrostatic ligand polarization.
利用激光烧蚀和脉冲喷嘴源在分子束中产生与铑的羰基和氮配合物。通过红外激光光解离光谱研究了Rh(CO)和Rh(N)形式的质量选择离子。碎片模式和红外光谱提供了这些配合物的配位和几何结构信息。相对于未配位配体的振动频率变化深入了解了所涉及的键合相互作用的性质。将实验谱带位置和强度与密度泛函理论（DFT）预测的结果进行比较。铑仅配位四个氮分子，而它可以容纳五个羰基配体。第五个CO配体位于轴向位置，其键合介于配位和溶剂化之间。Rh(CO)（2160 cm）中的羰基伸缩相对于分子CO振动（2143 cm）发生蓝移。相反，Rh(N)（2297 cm）中的N-N伸缩相对于自由N振动（2330 cm）发生红移。这些频移的相反方向通过σ供体和静电配体极化的组合来解释。
