Feng Rulin, Glendening Eric D, Peterson Kirk A
Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.
Department of Chemistry and Physics, Indiana State University, Terre Haute, Indiana 47809, United States.
Inorg Chem. 2020 Apr 6;59(7):4753-4763. doi: 10.1021/acs.inorgchem.9b03759. Epub 2020 Mar 18.
Thermochemical and spectroscopic properties for actinyl complexes involving UO and NpO with N and CO, together with the UO-O, UO-O, and UO-NO complexes, have been studied for the first time using an accurate composite coupled cluster approach. Two general bonding motifs were investigated, end-on (η) and side-on (η) relative to the metal center of the actinyls. For end-on CO complexes, both C-coordinated (An-C) and O-coordinated (An-O) structures were examined, with the former always being lower in energy. All of the η complexes were calculated to be stable, with dissociation energies ranging from 2 to 36 kcal/mol, except for that of UO-O (the η orientation for UO-NO was not amenable to single reference coupled cluster). In agreement with a previous study, the η structure for UO-O was calculated to be relatively strongly bound, by 22.3 kcal/mol in this work. The closely related NO complex, however, had a calculated dissociation energy of just 4.0 kcal/mol. The binding energy of O to neutral UO in a η orientation was calculated to be very strong, 75.4 kcal/mol, and strongly resembled a UO(O) complex at equilibrium. The N-N and C-O bonds were found to be somewhat activated for all the side-on (η) neutral An(IV) complexes, with stretching frequencies of N or CO being red-shifted by as much as 480 cm with a 0.06 Å bond length elongation. Dissociation energies for the η complexes are strongly correlated with the extent of electron transfer from ligand to actinyl. The nature of bonding in the actinyl complexes is examined using natural resonance theory (NRT). The correlation between bonding motif and small molecule activation is in agreement with experiments in condensed phases.
首次使用精确的复合耦合簇方法研究了涉及UO和NpO与N和CO的酰基配合物以及UO - O、UO - O和UO - NO配合物的热化学和光谱性质。研究了两种一般的键合模式，相对于酰基金属中心的端接（η）和侧接（η）。对于端接CO配合物，研究了C配位（An - C）和O配位（An - O）结构，前者能量总是较低。除UO - O外（UO - NO的η取向不适合单参考耦合簇），所有η配合物经计算都是稳定的，解离能范围为2至36千卡/摩尔。与先前的研究一致，UO - O的η结构经计算结合相对较强，在本研究中为22.3千卡/摩尔。然而，密切相关的NO配合物经计算解离能仅为4.0千卡/摩尔。O以η取向与中性UO的结合能经计算非常强，为75.4千卡/摩尔，在平衡时与UO(O)配合物非常相似。发现所有侧接（η）中性An(IV)配合物的N - N和C - O键都有所活化，N或CO的伸缩频率红移高达480厘米，键长伸长0.06埃。η配合物的解离能与从配体到酰基的电子转移程度密切相关。使用自然共振理论（NRT）研究了酰基配合物中的键合性质。键合模式与小分子活化之间的相关性与凝聚相中的实验结果一致。
