AI 中文总结
本研究通过计算探究13种NHCP氢化金配合物的成键与反应性，明确NHC部分调控NHCP的电子与空间性质，揭示其σ-给体能力反转等特性，为NHCP配体设计及小分子活化应用提供依据。
AI 中文摘要
新兴的氮杂环卡宾-磷宾（NHCP）配体的配位性质被报道受卡宾（NHC）部分的强烈影响，但目前仍缺乏清晰的理解。本研究采用无偏计算方案，系统探究了13种带有不同类别NHC的NHCP氢化金配合物[NHCPAuH]的成键特征与反应性，并与卡宾类似物进行了对比。分析显示，尽管NHCP的π-受体能力趋势与NHC的π-受体能力趋势定性相似，但其σ-给体能力趋势发生反转：σ-给体能力更强的NHC部分会生成σ-给体能力更弱的NHCP配体。同时，NHC部分的性质会影响P中心的配位几何，CNHC-P-Au键角可作为监测和/或设计具有所需σ-给体性质的NHCP配体的结构指标。研究还表明，与NHC相比，NHCP更强的σ-给体能力、更弱的π-受体能力，以及其独特的结构灵活性和电子适应性，均由卡宾部分通过调控HOMO孤对电子能量及其磷原子3p轨道特征直接控制。以CO2作为NHCP在小分子活化过程中潜在应用的探针，对[NHCPAuH]配合物反应性的研究显示，其反应机制定性相似，但活化能垒显著不同，且该能垒与NHCP的σ-给体能力直接相关，反映了其成键性质的高可调性。本研究为NHCP配体的设计原理提供了见解与视角，重点关注NHC部分在调控其电子和空间性质中的关键作用，为其在不同领域的新兴应用提供了机遇。
英文摘要
The coordination properties of the emerging class of N-heterocyclic carbene-phosphinidene (NHCP) ligands have been reported to be strongly affected by the carbene (NHC) moiety, but a clear understanding remains strikingly limited. In this work the bonding features and reactivity of 13 NHCP gold hydride complexes, [NHCPAuH], bearing different classes of NHCs have been systematically explored and compared to carbene analogues, using an unbiased computational protocol. The analyses reveal that, although the $π$-acceptor ability trend of NHCPs qualitatively parallels that of NHCs, the $σ$-donor ability trend reverses, with more $σ$-donating NHC moieties generating less $σ$-donating NHCP ligands. Concurrently, the nature of the NHC moiety impacts the coordination geometry at the P center, with the CNHC-P-Au bond angle appearing as a structural descriptor to monitor and/or design NHCP ligands with desired $σ$-donor properties. The NHCPs stronger $σ$-donor and weaker $π$-acceptor abilities compared to NHCs and their unique structural flexibility and electronic adaptability have been showcased to be directly controlled by the carbene moiety via modulation of the HOMO lone pair energy and its atomic phosphorous 3p character. The reactivity of [NHCPAuH] complexes with CO2, taken as a probe for potential NHCP applications in small molecule activation processes, demonstrates qualitatively similar mechanisms, with remarkably different activation barriers, which directly correlate with the NHCPs $σ$-donor ability, thus reflecting the high tunability of their bonding properties. This work provides insights and perspectives on the design principle of NHCP ligands, with a spotlight on the pivotal role of NHC moiety in modulating their electronic and steric properties, offering opportunities for burgeoning applications across diverse fields.
