Syntheses, Characterizations, and X-ray Structures of Alkali Metal Derivatives of Titanium(IV) Neopentoxides

Reactions of titanium(IV) neopentoxide, [Ti(μ-Oneo-Pe)(Oneo-Pe)3]2 (1, Oneo-Pe = OCH2CMe3), with alkali
neopentoxides (AOneo-Pe) resulted in the isolation of the dimeric complexes [ATi(Oneo-Pe)5]2 [A = Li (2), Na
(3), and K (4)], independent of the alkali metal investigated. Each compound was characterized by solution and
solid-state multinuclear NMR, isopiestic molecular weight determination, and/or single-crystal X-ray diffraction.
In the solid state, both 2 and 4 were found to adopt a standard [MM‘(OR)5]2 arrangement, wherein the Ti metals
are in a distorted trigonal-bipyramidal geometry and each alkali metal center is four-coordinated. Suitable crystals
of 3 were not isolated, but solid-state MAS (17O, 13C, xA) NMR spectroscopy indicated that the solid-state structure
of 3 was consistent with its congeners. Multinuclear (1H, 7Li, 13C, 17O, 23Na) solution NMR spectroscopy data in
toluene revealed that 2 exists in a complex multinuclear equilibrium, whereas 3 and 4 exist as mononuclear
species in solution.

四价钛新戊氧基配合物[Ti(μ-Oneo-Pe)(Oneo-Pe)₂]₂（化合物1，其中Oneo-Pe代表OCH₂CMe₃）与碱金属新戊氧基化合物AOneo-Pe反应后，无论所用碱金属种类如何，均可分离得到二聚体配合物[ATi(Oneo-Pe)₅]₂ [A为锂(Li，化合物2)、钠(Na，3)和钾(K，4)]。所有目标化合物均通过溶液态与固态多核核磁共振（Nuclear Magnetic Resonance, NMR）、等压分子量测定以及/或单晶X射线衍射进行了表征。固态结构分析表明，配合物2和4均采用典型的[MM‘(OR)₅]₂二聚体排布，其中钛原子处于畸变三角双锥配位几何环境，每个碱金属中心为四配位。配合物3的合格单晶未能获得，但固态魔角旋转（Magic Angle Spinning, MAS）17O、13C、xA核磁共振光谱分析显示，其固态结构与同系物一致。甲苯溶剂中的多核（1H、7Li、13C、17O、23Na）溶液核磁共振光谱数据表明，配合物2在溶液中存在复杂的多核平衡，而配合物3和4在溶液中以单核物种形式存在。