Del Horno Estefanía, Jover Jesús, Mena Miguel, Pérez-Redondo Adrián, Yélamos Carlos
Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), Universidad de Alcalá, 28805 Alcalá de, Henares-Madrid, Spain.
Secció de Química Inorgànica, Departament de Química Inorgànica i Orgànica, Institut de Química Teòrica i Computacional (IQTC-UB), Universitat de Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
Chemistry. 2022 Jan 19;28(4):e202103085. doi: 10.1002/chem.202103085. Epub 2021 Dec 2.
Low-valent titanium species were prepared by reaction of [TiCpX ] (Cp=η -C Me ; X=Cl, Br, Me) with LiEH (E=Al, B) or BH (thf), and their structures elucidated by experimental and theoretical methods. The treatment of trihalides [TiCpX ] with LiAlH in ethereal solvents (L) leads to the hydride-bridged heterometallic complexes [{TiCp(μ-H)} {(μ-H) AlX(L)} ] (L=thf, X=Cl, Br; L=OEt , X=Cl). Density functional theory (DFT) calculations for those compounds reveal an open-shell singlet ground state with a Ti-Ti bond and can be described as titanium(II) species. The theoretical analyses also show strong interactions between the Ti-Ti bond and the empty s orbitals of the Al atom of the AlH XL fragments, which behave as σ-accepting (Z-type) ligands. Analogous reactions of [TiCpX ] with LiBH (2 and 3 equiv.) in tetrahydrofuran at room temperature and at 85 °C lead to the titanium(III) compounds [{TiCp(BH )(μ-X)} ] (X=Cl, Br) and [{TiCp*(BH )(μ-BH )} ], respectively. The treatment of [TiCpMe ] with 4 and 5 equiv. of BH (thf) produces the diamagnetic [{TiCp(BH Me)} (μ-B H )] and paramagnetic [{TiCp*(μ-B H )} ] complexes, respectively.
低价钛物种通过[TiCpX ]（Cp = η⁵-C₅Me₅；X = Cl、Br、Me）与LiEH（E = Al、B）或BH₃(thf)反应制备，并通过实验和理论方法阐明其结构。在醚类溶剂（L）中用LiAlH₄处理三卤化物[TiCpX ]会生成氢化物桥连的异金属配合物[{TiCp(μ-H)}₂{(μ-H)₂AlX(L)}₂]（L = thf，X = Cl、Br；L = OEt₂，X = Cl）。对这些化合物的密度泛函理论（DFT）计算表明其基态为开壳单重态，存在Ti-Ti键，可描述为钛（II）物种。理论分析还表明Ti-Ti键与AlH₃XL片段中Al原子的空s轨道之间存在强相互作用，AlH₃XL片段表现为σ-接受（Z型）配体。[TiCpX ]与LiBH₄（2和3当量）在室温及85℃的四氢呋喃中进行类似反应，分别生成钛（III）化合物[{TiCp(BH₄)(μ-X)}₂]（X = Cl、Br）和[{TiCp*(BH₄)(μ-BH₄)}₂]。用4和5当量的BH₃(thf)处理[TiCpMe ]分别生成抗磁性的[{TiCp(BH₃Me)}₂(μ-B₂H₄)]和顺磁性的[{TiCp*(μ-B₂H₄)}₂]配合物。
