Synthesis, structure, and hydride-deuteride exchange studies of CpMoH(3)(PMe(2)Ph)(2) and theoretical studies of the CpMoH(3)(PMe(3))(2) model system
Synthesis, structure, and hydride-deuteride exchange studies of CpMoH(3)(PMe(2)Ph)(2) and theoretical studies of the CpMoH(3)(PMe(3))(2) model system
复制标题
DOI：
10.1021/om960360o
复制
发表时间：
1997-03-18
期刊：
影响因子：
2.8
通讯作者：
Hall, MB
中科院分区：
文献类型：
--
作者：
Abugideiri, F;Fettinger, JC;Hall, MB
介绍了CpMoH(3)(PMe（2)Ph)(2), 1）的合成和表征。化合物1由CpMoCl(3)、PMe(2)Ph和LiAlH4反应得到，产率为61%。化合物1也由CpMo(o-C(6)H(4)PMe(2))(PMe(2)Ph)(2)与H-2反应得到。通过H-1和p -31核磁共振光谱对1的表征表明，即使在低温下，氢化物原子也具有高度的流动性。单晶x射线结构表明其几何形状为伪八面体，三个H配体和两个PMe(2)Ph配体相对排列在相对的反式位置。这与之前报道的Mo（IV）三氢化物的另一种结构Cp*MoH3（dppe）形成鲜明对比，后者采用伪三角棱柱结构。Mo-P平均2.41(8)；和Mo-H距离（平均1.64(4)埃）与在Cp*MoH3（dppe）中发现的相似。最接近的H-H距离为1.79埃，与经典氢化物一致。对CpMoH(3)(PMe(3))(2)模型在不同构型下的从头计算结果与实验结果一致，表明可能存在一种由拜拉扭转组成的氢化物交换机制，该机制可使伪八面体、反、面几何结构相互转换。研究了C6D6中1的氢化物-氘化物交换过程。
The synthesis and characterization of CpMoH(3)(PMe(2)Ph)(2), 1, is described. Compound 1 is obtained from the reaction between CpMoCl(3), PMe(2)Ph, and LiAlH4, in 61% yield. Compound 1 has also been obtained from the reaction of CpMo(o-C(6)H(4)PMe(2))(PMe(2)Ph)(2) with H-2. Characterization of 1 by H-1- and P-31-NMR spectroscopies shows a high degree of fluxionality for the hydride atoms, even at low temperatures. A single-crystal X-ray structure indicates that the geometry is pseudo-octahedral, with a relative mer arrangement of the three H ligands and the two PMe(2)Ph ligands occupying relative trans positions. This is in contrast with the only other previously reported structure of a Mo(IV) trihydride, Cp*MoH3(dppe), which adopts a pseudo trigonal prismatic structure. The Mo-P (average 2.41(8); Angstrom) and Mo-H distances (average 1.64(4) Angstrom) are similar to those found in Cp*MoH3(dppe). The closest H-H distance is 1.79 Angstrom consistent with a classical hydride. The results of ab initio calculations for the CpMoH(3)(PMe(3))(2) model in different configurations agree with the experimental observations and suggest that a mechanism of hydride exchange consisting of a Bailar twist, which interconverts pseudo-octahedral mer, trans and fac geometries, is possible. The process of hydride-deuteride exchange of 1 in C6D6 is also examined.