A high-spin, mononuclear Ti^II complex, [(Tp^tBu,Me)TiCl] [Tp^tBu,Me– = hydridotris(3-tert-butyl-5-methylpyrazol-1-yl)borate], confined to a tetrahedral ligand-field environment, has been prepared by reduction of the precursor [(Tp^tBu,Me)TiCl₂] with KC₈. Complex [(Tp^tBu,Me)TiCl] has a ³A₂ ground state (assuming C_3v symmetry based on structural studies), established via a combination of high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy, solution and solid-state magnetic studies, Ti K-edge X-ray absorption spectroscopy (XAS), and both density functional theory and ab initio (complete-active-space self-consistent-field, CASSCF) calculations. The formally and physically defined Ti^II complex readily binds tetrahydrofuran (THF) to form the paramagnetic adduct [(Tp^tBu,Me)TiCl(THF)], which is impervious to N₂ binding. However, in the absence of THF, the Ti^II complex captures N₂ to produce the diamagnetic complex [(Tp^tBu,Me)TiCl]₂(η¹,η¹;μ₂-N₂), with a linear Ti═N═N═Ti topology, established by single-crystal X-ray diffraction. The N₂ complex was characterized using XAS as well as IR and Raman spectroscopies, thus establishing this complex to possess two Ti^III centers covalently bridged by an N₂^2– unit. A π acid such as CNAd (Ad = 1-adamantyl) coordinates to [(Tp^tBu,Me)TiCl] without inducing spin pairing of the d electrons, thereby forming a unique high-spin and five-coordinate Ti^II complex, namely, [(Tp^tBu,Me)TiCl(CNAd)]. The reducing power of the coordinatively unsaturated Ti^II-containing [(Τp^tBu,Me)TiCl] species, quantified by electrochemistry, provides access to a family of mononuclear Ti^IV complexes of the type [(Tp^tBu,Me)Ti═E(Cl)] (with E^2– = NSiMe₃, N₂CPh₂, O, and NH) by virtue of atom- or group-transfer reactions using various small molecules such as N₃SiMe₃, N₂CPh₂, N₂O, and the bicyclic amine 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene.

中文翻译：

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单核高旋转四面体Ti ^II复合物

高自旋，单核Ti ^II复合物[[（Tp ^{t Bu，Me}）TiCl] [Tp ^{t Bu，Me–} =氢化三（3-叔丁基-5-甲基吡唑-1-基）硼酸盐]，通过用KC ₈还原前体[（Tp ^{t Bu，Me}）TiCl ₂ ]制备了四面体配体场环境。络合物[（Tp ^{t Bu，Me}）TiCl]具有³ A ₂基态（根据结构研究假设C _{3 v}对称），通过结合了高频和场电子顺磁共振（HFEPR）光谱，溶液和固态磁研究，Ti K边缘X射线吸收光谱（XAS）以及密度泛函理论和从头算（完全活性空间自洽字段（CASSCF）计算。形式上和物理上定义的Ti ^II复合物很容易与四氢呋喃（THF）结合形成顺磁性加合物[（Tp ^{t Bu，Me}）TiCl（THF）]，它不渗透N ₂。然而，在不存在的THF中，在Ti ^II复杂捕获Ñ ₂，以产生反磁性络合物[（TP^{吨卜中，Me}）的TiCl] ₂（η ¹，η ¹;μ ₂ -N ₂），用线性Ti═N═N═Ti拓扑，通过单晶X射线衍射确定。使用XAS以及IR和拉曼光谱对N ₂络合物进行了表征，从而确定了该络合物具有两个由N ₂ ^2-单元共价桥接的Ti ^III中心。诸如CNAd（Ad = 1-金刚烷基）之类的π酸与[（Tp ^{t Bu，Me}）TiCl]配位而不会引起d电子的自旋配对，从而形成独特的高自旋和五坐标Ti ^II配合物，即，[（Tp ^{t Bu，Me}）TiCl（CNAd）]。含不饱和Ti ^II的[（Τp^{t Bu，Me}）TiCl]种类，通过电化学定量，可以访问[[Tp ^{t Bu，Me}）Ti═E（Cl）]类型的单核Ti ^IV配合物族（其中E ^2– = NSiMe ₃， N ₂ CPh ₂，O和NH）借助原子转移或基团转移反应，使用各种小分子，例如N ₃ SiMe ₃，N ₂ CPh ₂，N ₂ O和双环胺2,3：5， 6-二苯并-7-氮杂双环[2.2.1]庚-2,5-二烯。