Crystal structure and computational investigation of an analogue of Grubbs' second generation catalyst with a fluorous phosphine.
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A fluorous phosphine analogue of Grubbs' second generation olefin metathesis catalyst, (H(2)IMes)((R(f8)(CH(2))(2))(3)P)(Cl)(2)Ru(=CHPh) (1; H(2)IMes/R(f8) = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene/(CF(2))(7)CF(3)) 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.