Syntheses and Structures of Molybdenum Imido Alkylidene Pyrrolide and Indolide Complexes

An X-ray structural study of Mo(NAd)(CHCMe2Ph)(2,5-Me2NC4H2)2 (1; Ad = 1-adamantyl) reveals it to contain one η1-2,5-Me2NC4H2 ring and one η5-2,5-Me2NC4H2 ring. The structures of Mo(NAr)(CHCMe2Ph)(pyrrolide)2 (Ar = 2,6-i-Pr2C6H3) complexes that contain 2,3,4,5-tetramethylpyrrolides, 2,5-diisopropylpyrrolides, or 2,5-diphenylpyrrolides are analogous to that of 1. In contrast, Mo(NAr)(CH2CMe2Ph)(indolide)2 (6) was shown to contain two η1-bound indolides. Monohexafluoro-t-butoxide pyrrolide (MAP) species can be prepared, either through addition of one equiv of Me(CF3)2COH to a bispyrrolide or through reactions between the lithium pyrrolide and the bishexafluoro-t-butoxide. A trimethylphosphine adduct of a bispyrrolide, Mo(NAd)(CHCMe2Ph)(η1-NC4H4)2(PMe3), has been prepared and structurally characterized, while a PMe3 adduct of MAP hexafluoro-t-butoxide species was found to have PMe3 bound approximately trans to the pyrrolide. This adduct serves as a model for the structure of the initial olefin adduct in olefin metathesis.对配合物Mo(NAd)(CHCMe₂Ph)(2,5-Me₂NC₄H₂)₂（化合物1；Ad=1-金刚烷基（1-adamantyl））的X射线结构研究表明，其结构中含有一个η¹-2,5-二甲基吡咯环与一个η⁵-2,5-二甲基吡咯环。含有2,3,4,5-四甲基吡咯阴离子（pyrrolide）、2,5-二异丙基吡咯阴离子或2,5-二苯基吡咯阴离子的Mo(NAr)(CHCMe₂Ph)(吡咯基)₂（Ar=2,6-二异丙基苯基（2,6-i-Pr₂C₆H₃））配合物，其结构与化合物1类似。与之相反，配合物Mo(NAr)(CH₂CMe₂Ph)(吲哚基)₂（化合物6）被证实含有两个η¹配位的吲哚阴离子（indolide）。单六氟叔丁氧基吡咯基（Monohexafluoro-t-butoxide pyrrolide, MAP）配合物可通过两种路径制备：一是向双吡咯基金属配合物中加入1当量的Me(CF₃)₂COH；二是通过吡咯基锂与双六氟叔丁氧基金属配合物的反应合成。已制备双吡咯基配合物的三甲基膦（trimethylphosphine, PMe3）加合物Mo(NAd)(CHCMe₂Ph)(η¹-NC₄H₄)₂(PMe₃)并完成其结构表征；而MAP六氟叔丁氧基配合物的三甲基膦加合物中，三甲基膦的配位位置大致位于与吡咯基反式的方向。该加合物可作为烯烃复分解反应（olefin metathesis）中初始烯烃加合物的结构模型。