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首页> 外文期刊>Chemistry: A European journal >Electronic Perturbation in a Molecular Nanowire of [IrCl5(NO)]~- Units
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Electronic Perturbation in a Molecular Nanowire of [IrCl5(NO)]~- Units

机译：[IrCl5（NO）]〜-分子纳米线中的电子摄动

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摘要

The nitrosyl in [IrCl5(NO)]~-is probably the most electrophilic known to date. This fact is reflected by its extremely high IR frequency in the solid state, electrochemical behavior, and remarkable reactivity in solution. PPh4[IrCl5(NO)] forms a crystal in which the [IrCl5(NO)]~- anions are in a curious wire-like linear arrangement, in which the distance between the N-O moiety of one anion and the trans chloride of the upper one nearby is only 2.8 A. For the same complex [IrCl5(NO)]~- but with a different coun-terion, Na[IrCl5(NO)], the anions are stacked one over the other in a side-by-side arrangement. In this case the electronic distribution can be depicted as the closed-shell electronic structure Ir~(III)-NO~+, as expected for any d~6 third-row transition metal complex. However, in PPh4[IrCl5(NO)] an unprecedented electronic perturbation takes place, probably due to NO~(centre dot)-Cl~- acceptor-donor interactions among a large number of [IrCl5(NO)]~- units, favoring a different electronic distribution, namely the open-shell electronic structure Ir~(IV)-NO~(centre dot). This conclusion is based on XANES experimental evidence, which demonstrates that the formal oxidation state for iridium in PPh_4-[IrCl5(NO)] is +4, as compared with +3 in K[IrCl5(NO)]. In agreement, solid-state DFT calculations show that the ground state for [IrCl5(NO)]~- in the PPh_4~+ salt comprises an open-shellsinglet with an electronic structure which encompasses half of the spin density mainly localized on a metal-centered orbital, and the other half on an NO-based orbital. The electronic perturbation could be seen as an electron promotion from a metal-chloride to a metal-NO orbital, due to the small HOMO-LUMO gap in PPh_4-[IrCl5(NO)]. This is probably induced by electrostatic interactions acting as a result of the closeness and wire-like spatial arrangement of the Ir metal centers, imposed by lattice forces due to pi-pi stacking interactions among the phenyl rings in PPh_4~+. Experimental and theoretical data indicate that in PPh_4[IrCl5(NO)] the Ir-N-O moiety is partially bent and tilted.
机译：[IrCl5（NO）]〜中的亚硝酰基可能是迄今为止已知的最亲电子的。这一事实通过其在固态中极高的IR频率，电化学行为以及在溶液中的出色反应性得以反映。 PPh4 [IrCl5（NO）]形成的晶体中，[IrCl5（NO）]-阴离子呈奇特的线状线性排列，其中一个阴离子的NO部分与上层的反式氯化物之间的距离附近的一个离子只有2.8A。对于相同的络合物[IrCl5（NO）]〜-，但Na（IrCl5（NO）]的离子不同，阴离子彼此并排堆叠安排。在这种情况下，电子分布可以描述为闭壳电子结构Ir〜（III）-NO〜+，正如任何d〜6第三行过渡金属络合物所期望的那样。然而，在PPh4 [IrCl5（NO）]中发生了前所未有的电子干扰，这可能是由于大量[IrCl5（NO）]〜-单元之间的NO〜（中心点）-Cl〜-受体-供体相互作用所致。一个不同的电子分布，即开壳式电子结构Ir〜（IV）-NO〜（中心点）。该结论基于XANES实验证据，该证据表明PPh_4- [IrCl5（NO）]中铱的形式氧化态为+4，而K [IrCl5（NO）]中为+3。一致的是，固态DFT计算表明，PPh_4〜+盐中[IrCl5（NO）]〜-的基态包括具有电子结构的开壳小分子，该结构包含一半的自旋密度，主要位于金属-中心轨道，另一半位于基于NO的轨道上。由于PPh_4- [IrCl5（NO）]中的HOMO-LUMO间隙很小，电子摄动可以看作是从金属氯化物到金属NO轨道的电子促进。这可能是由于Ir金属中心的紧密性和金属线状空间排列所引起的静电相互作用引起的，该静电相互作用是由于PPh_4〜+中苯环之间的pi-pi堆积相互作用所引起的晶格力所致。实验和理论数据表明，在PPh_4 [IrCl5（NO）]中，Ir-N-O部分被部分弯曲和倾斜。

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