d4 [Mo(CO)2(η-PhC≡CPh)Tp']⁺单电子还原的结构后果以及d5自由基[M(CO)L(η-MeC≡CMe)Tp'] {L = CO和P(OCH2)3CEt}的电子结构

Structural consequences of the one-electron reduction of d4 [Mo(CO)2(eta-PhC[triple bond]CPh)Tp']+ and the electronic structure of the d5 radicals [M(CO)L(eta-MeC[triple bond]CMe)Tp'] {L = CO and P(OCH2)3CEt}.

作者信息

Adams Christopher J, Bartlett Ian M, Boonyuen Supakorn, Connelly Neil G, Harding David J, Hayward Owen D, McInnes Eric J L, Orpen A Guy, Quayle Michael J, Rieger Philip H

机构信息

School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK.

出版信息

Dalton Trans. 2006 Jul 28(28):3466-77. doi: 10.1039/b514951g. Epub 2006 Mar 1.

DOI:10.1039/b514951g

PMID:16832497

Abstract

Reduction of [M(CO)2(eta-RC[triple bond]CR')Tp']X {Tp' = hydrotris(3,5-dimethylpyrazolyl)borate, M = Mo, X = [PF6]-, R = R' = Ph, C6H4OMe-4 or Me; R = Ph, R' = H; M = W, X = [BF4]-, R = R' = Ph or Me; R = Ph, R' = H} with [Co(eta-C5H5)2] gave paramagnetic [M(CO)2(eta-RC[triple bond]CR')Tp'], characterised by IR and ESR spectroscopy. X-Ray structural studies on the redox pair [Mo(CO)2(eta-PhC[triple bond]CPh)Tp'] and [Mo(CO)2(eta-PhC[triple bond]CPh)Tp'][PF6] showed that oxidation is accompanied by a lengthening of the C[triple bond]C bond and shortening of the Mo-C(alkyne) bonds, consistent with removal of an electron from an orbital antibonding with respect to the Mo-alkyne bond, and with conversion of the alkyne from a three- to a four-electron donor. Reduction of [Mo(CO)(NCMe)(eta-MeC[triple bond]CMe)Tp'][PF6] with [Co(eta-C5H5)2] in CH2Cl2 gives [MoCl(CO)(eta-MeC[triple bond]CMe)Tp'], via nitrile substitution in [Mo(CO)(NCMe)(eta-MeC[triple bond]CMe)Tp'], whereas a similar reaction with [M(CO){P(OCH2)3CEt}(eta-MeC[triple bond]CMe)Tp']+ (M = Mo or W) gives the phosphite-containing radicals [M(CO){P(OCH2)3CEt}(eta-MeC[triple bond]CMe)Tp']. ESR spectroscopic studies and DFT calculations on [M(CO)L(eta-MeC[triple bond]CMe)Tp'] {M = Mo or W, L = CO or P(OCH2)3CEt} show the SOMO of the neutral d5 species (the LUMO of the d4 cations) to be largely d(yz) in character although much more delocalised in the W complexes. Non-coincidence effects between the g and metal hyperfine matrices in the Mo spectra indicate hybridisation of the metal d-orbitals in the SOMO, consistent with a rotation of the coordinated alkyne about the M-C2 axis.

摘要

用[Co(η-C₅H₅)₂]还原[M(CO)₂(η-RC≡CR')Tp'] {Tp' = 氢三(3,5-二甲基吡唑基)硼酸根，M = Mo，X = [PF₆]⁻，R = R' = Ph、对甲氧基苯基或Me；R = Ph，R' = H；M = W，X = [BF₄]⁻，R = R' = Ph或Me；R = Ph，R' = H}得到顺磁性的[M(CO)₂(η-RC≡CR')Tp']，通过红外光谱和电子顺磁共振光谱对其进行了表征。对氧化还原对[Mo(CO)₂(η-PhC≡CPh)Tp']和[Mo(CO)₂(η-PhC≡CPh)Tp'][PF₆]的X射线结构研究表明，氧化伴随着C≡C键的延长和Mo-C(炔烃)键的缩短，这与从相对于Mo-炔烃键的反键轨道上移除一个电子以及炔烃从三电子供体转变为四电子供体相一致。在二氯甲烷中用[Co(η-C₅H₅)₂]还原[Mo(CO)(NCMe)(η-MeC≡CMe)Tp'][PF₆]，通过[Mo(CO)(NCMe)(η-MeC≡CMe)Tp']中的腈取代反应得到[MoCl(CO)(η-MeC≡CMe)Tp']，而与[M(CO){P(OCH₂)₃CEt}(η-MeC≡CMe)Tp']⁺（M = Mo或W）进行类似反应得到含亚磷酸酯的自由基[M(CO){P(OCH₂)₃CEt}(η-MeC≡CMe)Tp']。对[M(CO)L(η-MeC≡CMe)Tp'] {M = Mo或W，L = CO或P(OCH₂)₃CEt}的电子顺磁共振光谱研究和密度泛函理论计算表明，中性d⁵物种（d⁴阳离子的最低未占分子轨道）的单占据分子轨道在很大程度上具有d(yz)特征，尽管在W配合物中更离域。Mo光谱中g和金属超精细矩阵之间的非巧合效应表明单占据分子轨道中金属d轨道的杂化，这与配位炔烃围绕M-C₂轴的旋转相一致。