Synthesis and Reactivity of 16-Electron Cycloheptatrienyl-Molybdenum(0) Complexes with Bis(imidazolin-2-imine) Ligands

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• 作者：Dejan Petrovic ; Cristian G. Hrib ; S&#xf6 ; ren Randoll ; Peter G. Jones ; Matthias Tamm
• 刊名：Organometallics
• 出版年：2008
• 出版时间：February 25, 2008
• 年：2008
• 卷：27
• 期：4
• 页码：778 - 783
• 全文大小：162K
• 年卷期：v.27,no.4(February 25, 2008)
• ISSN：1520-6041

文摘

The reaction of the ligands 1,2-bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-imino)ethane (BL^iPr) and 1,2-bis(1,3,4,5-tetramethylimidazolin-2-imino)ethane (BL^Me) with the cycloheptatrienyl-molybdenum complex [(η⁷-C₇H₇)Mo(CH₃CN)₃]X (X = BF₄, PF₆) leads to acetonitrile substitution and formation of stable 16-electron half-sandwich complexes (η⁷-C₇H₇)Mo(BL^iPr)]BF₄, [1]BF₄, and [(η⁷-C₇H₇)Mo(BL^Me)]X, [2]X (X = BF₄, PF₆), two of which could be crystallographically characterized to reveal undistorted two-legged piano stool geometries. Cyclovoltammetric studies exhibit very negative redox potentials of E° = −1.095 V and E° = −1.138 V versus the ferrocene/ferrocenium couple (0 V), indicative of very electron-rich metal complexes. Oxidation of [2]X with (η⁷-C₇H₇)BF₄ or [Fe(η⁵-C₅H₅)₂]PF₆ furnished the Mo(I) complexes of general formula [(η⁷-C₇H₇)Mo(BL^Me)(CH₃CN)]X₂, [3]X₂ (X = BF₄, PF₆), which display a three-legged piano stool geometry in the solid state by coordination of one additional acetonitrile molecule to molybdenum. The same geometry is observed upon reaction of [1]BF₄ and [2]PF₆ with 2,6-dimethylphenyl isocyanide (XyNC) to afford the isocyanide complexes [1(CNXy)]BF₄ and [2(CNXy)]PF₆. Their CN stretching vibrations are observed at 2041 and 2030 cm⁻¹, confirming the electron richness and strong π-electron-releasing capability of the molybdenum-imine moiety.