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A Search by NBO Analysis for Syndetic Donation in Known X‐ray Structures of Transition Metal Complexes with Close Aromatic Ring C–H···Metal Approaches
European Journal of Inorganic Chemistry ( IF 2.2 ) Pub Date : 2020-06-04 , DOI: 10.1002/ejic.202000336
M. Arif Sajjad 1 , Peter Schwerdtfeger 1 , John A. Harrison 2 , Alastair J. Nielson 2
Affiliation  

Natural bond orbital (NBO) analysis obtained from density functional theory (DFT) calculations shows that where close approaches of aromatic ring C–H bond hydrogens to transition metal centers indicate an agostic interaction might be present, the angle the ring makes with the coordination plane and the metal··· Cagostic separation can determine how significant are the agostic, syndetic (π or σ‐electron density in the vicinity of the agostic carbon interacting with a metal center) and back‐donations that are present. The study reveals that in the few X‐ray crystal structures that are known where agostic bonding is present, the interaction is weak, but the presence of syndetic donation is confirmed in the solid state but is small in magnitude. Agostic interactions present in a Co‐aminophosphane, and Ir and Ru 2‐phenylpyridine complexes show syndetic π‐donation components with NBO E (2) values of only 3.2, 2.1 and 2.1 kcal mol–1 respectively whereas a Rh tris‐triphenylphosphine cation shows minimal agostic donation and η2π‐donation and a Pd complex with two dicyclohexylbiphenylphosphine ligands has minimal agostic or syndetic components and appears to contain unusual aromatic ring rotations between the anagostic and agostic states. The work reinforces the multicomponent nature of agostic interactions involving aromatic rings.

中文翻译:

通过NBO分析寻找具有紧密芳族环C–H··金属方法的过渡金属配合物在已知X射线结构中的合成捐赠

从密度泛函理论(DFT)计算获得的自然键轨道(NBO)分析表明,如果芳族环C–H键氢与过渡金属中心的紧密接近表明可能存在有害的相互作用,则该环与配位平面所成的角度和金属··· ç agostic分离可确定如何显著是agostic,syndetic(πσ-碳原子与金属中心相互作用附近的电子密度和存在的背捐赠。研究表明,在少数存在X射线键合的X射线晶体结构中,相互作用较弱,但在固态中证实存在联合捐赠,但数量很少。共氨基膦,Ir和Ru 2-苯基吡啶配合物中存在的强相互作用表明,合成的π-供体组分的NBO E(2)值分别仅为3.2、2.1和2.1 kcal mol –1,而Rh三-三苯基膦阳离子显示最小agostic捐赠和η 2 - π捐赠和具有两个二环己基联苯膦配体的Pd络合物具有最小的扰动或同调成分,并且似乎在反常状态和残酷状态之间包含不寻常的芳香环旋转。这项工作加强了涉及芳香环的异常相互作用的多组分性质。
更新日期:2020-07-16
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