A π-Donor Spectrochemical Series for X in (Me5C5)2TiX, and β-Agostic Interactions in X = Et and N(Me)Ph
A π-Donor Spectrochemical Series for X in (Me5C5)2TiX, and β-Agostic Interactions in X = Et and N(Me)Ph
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(Me5C5)2TiX 中 X 的 π-供体光谱化学系列，以及 X = Et 和 N(Me)Ph 中 β-不规则相互作用
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发表时间：
1996
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影响因子：
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通讯作者：
R. Andersen
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作者：
W. Lukens;Milton R. Smith;R. Andersen
研究了 Cp*2TiX 型 d1-弯曲茂金属化合物的 EPR 和电子光谱，其中 X 是卤化物、醇盐、酰胺、烷基或氢化物，Cp* = Me5C5。其中一些化合物是新化合物，其中 X = N(Me)H 和 F 的化合物通过 X 射线晶体学进行了表征。 Cp*2TiN(Me)H 的晶体结构表明，N(Me)H 配体位于 Cp*(质心)−Ti−Cp*(质心) 定义的平面上。这是空间上最不利的构象，但允许最大的 Ti−N π 键合。采用 Petersen 和 Dahl 对 d1-茂金属 Cp2VX2 使用的方法分析各向异性冷冻溶液 EPR 光谱，得出 gx、gy 和 gz。虽然gx和gz的值在整个系列中相对恒定，但gy的值随着X的π给体能力而变化。π给体系列为N(Me)H ≈ NH2 ≈ OMe > OPh ≈ F > N(Me)Ph > Cl > Br > I > H。已知烷基中，π给体能力为Et > Me > n-Pr ≈ CH2CMe3 > CH2C6H5，即部分地通过 β-agostic 相互作用合理化......
The EPR and electronic spectra of d1-bent metallocene compounds of the type Cp*2TiX, where X is halide, alkoxide, amide, alkyl, or hydride and Cp* = Me5C5, have been studied. Several of these compounds are new, and those with X = N(Me)H and F were characterized by X-ray crystallography. The crystal structure of Cp*2TiN(Me)H showed that the N(Me)H ligand lies on the plane defined by Cp*(centroid)−Ti−Cp*(centroid). This is the sterically most unfavorable conformation but allows maximum Ti−N π-bonding. The anisotropic frozen solution EPR spectra were analyzed by the method used by Petersen and Dahl for the d1-metallocenes, Cp2VX2, which gives gx, gy, and gz. Although the values of gx and gz are relatively constant throughout the series, the value of gy varies with the π-donor ability of X. The π-donor series is N(Me)H ≈ NH2 ≈ OMe > OPh ≈ F > N(Me)Ph > Cl > Br > I > H. Among the known alkyls, the π-donor ability was Et > Me > n-Pr ≈ CH2CMe3 > CH2C6H5, which is rationalized, in part, by a β-agostic interaction...