Steric interaction between terminal allyl substituent and the proximal 3-methyl group of the pyrazole can result in a severe distortion of the π-allyl orientation, as diagnosed by the downfield chemical shift of the central proton of the allyl group and confirmed by the X-ray crystal structure of a π-cinnamyl complex of molybdenum containing hydrotris-(3,5-dimethylpyrazolyl)borate ligand.
末端烯丙基取代基与
吡唑的近端3-甲基之间的立体相互作用可导致π-烯丙基方向的严重变形,这是通过烯丙基中心质子的低场
化学位移诊断并通过X-含有氢三(
3,5-二甲基吡唑基)
硼酸酯配体的
钼的π-肉桂基络合物的X射线晶体结构。