Crystal Structure and Computational Investigation of an Analogue of Grubbs’ Second Generation Catalyst with a Fluorous Phosphine

A fluorous phosphine analogue of Grubbs’ second generation olefin metathesis catalyst, (H2IMes)­((Rf8(CH2)2)3P)­(Cl)2Ru­(=CHPh) (1; H2IMes/Rf8 = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene/(CF2)7CF3) is crystallized and the X-ray structure analyzed in detail. The bond lengths and angles about ruthenium are compared to those of two solvates and five derivatives of Grubbs’ second generation catalyst. All exhibit distorted square pyramidal geometries in which the alkylidene ligands occupy apical positions, and geometric trends are interpreted with the help of density functional calculations. The perfluoroalkyl groups (1) exhibit helical conformations, as manifested by various torsional relationships, (2) segregate in the lattice, and (3) align in pairs of opposite helical chiralities.第二代格拉布斯烯烃复分解催化剂的含氟膦类似物——(H₂IMes)·[(Rf₈(CH₂)₂)₃P]·Cl₂Ru(=CHPh)（化合物1；其中H₂IMes/Rf₈分别代表1,3-二均三甲苯基-4,5-二氢咪唑-2-亚基/(CF₂)₇CF₃）已完成晶体培养，并对其X射线晶体结构进行了详细解析。将钌中心周围的键长与键角参数，与两种溶剂化物及五种第二代格拉布斯催化剂衍生物的对应参数进行了对比。所有配合物均呈现扭曲的四方锥几何构型，其中亚烷基配体占据锥顶位置，且通过密度泛函计算对该类几何构型的变化趋势进行了解释。该化合物的全氟烷基基团展现出三类特征：(1) 以螺旋构象存在，该构象可通过各类扭转关系得以印证；(2) 在晶格中发生偏析；(3) 以相反螺旋手性的成对方式排布。