Ott Jonas C, Isak Daniel, Melder Julian J, Wadepohl Hubert, Gade Lutz H
Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany.
Inorg Chem. 2020 Oct 5;59(19):14526-14535. doi: 10.1021/acs.inorgchem.0c02315. Epub 2020 Sep 15.
The preparation and reactivity of a range of novel paramagnetic chromium(II) complexes supported by a carbazole-based PNP pincer ligand is reported. Deprotonation of the ligand precursors (PNP)H () and subsequent reaction with chromium(II) chloride led to the formation of square-planar chlorido complexes (PNP)CrCl (). Further reaction with various alkylating agents resulted in the isolation of chromium alkyl complexes (PNP)CrR' () which were then hydrogenated to yield two rare examples of paramagnetic chromium(II) hydrides and . Both compounds were characterized by X-ray diffraction and paramagnetic NMR spectroscopy supported by a comprehensive DFT-supported assignment of the resonances. While the di(-butyl)phosphino PNP substituted complex was found to exhibit a monomeric square-planar molecular structure, its isopropyl-substituted analog forms a dimer, also indicated by a strong antiferromagnetic coupling of the chromium centers. The pronounced reactivity of these compounds toward C═X double bonds was demonstrated by reaction with benzophenone, ,'-dicyclohexylcarbodiimide, and carbon dioxide, which gave the corresponding insertion products. The alkoxido complex , the amidinato complex , and the formato compound were also characterized by X-ray diffraction.
报道了一系列由咔唑基PNP钳形配体支持的新型顺磁性铬（II）配合物的制备及其反应活性。配体前体（PNP）H（）去质子化，随后与氯化铬（II）反应，生成平面正方形氯配合物（PNP）CrCl（）。与各种烷基化剂进一步反应，分离得到铬烷基配合物（PNP）CrR'（），然后将其氢化，得到两个罕见的顺磁性氢化铬（II）实例 和 。这两种化合物均通过X射线衍射和顺磁核磁共振光谱进行表征，并通过全面的密度泛函理论（DFT）支持的共振归属进行辅助。虽然发现二（丁基）膦基PNP取代的配合物 具有单体平面正方形分子结构，但其异丙基取代的类似物 形成二聚体，铬中心的强反铁磁耦合也表明了这一点。这些化合物与C═X双键的显著反应活性通过与二苯甲酮、，'-二环己基碳二亚胺和二氧化碳反应得到证明，反应生成了相应的插入产物。氧化合物 、脒基配合物 和甲酸酯化合物 也通过X射线衍射进行了表征。
