The effect of trifluoromethyl groups in the para positions of a perfluoroaryl phosphine: A comparison of the structures of [{η⁵,κP-C₅Me₄CH₂C₆F₃X-5-P(C₆F₄X-4)-2-CH₂P(C₆F₄X-4)₂}RhCl₂], X = F and CF₃

Abstract

The complex [{η⁵,κP-C₅Me₄CH₂C₆F₃CF₃-5-P(C₆F₄CF₃-4)-2-CH₂P(C₆F₄CF₃-4)₂}RhCl₂] (2) was formed by dehydrofluorinative carbon–carbon coupling in the reaction between bis{bis(4-trifluoromethyltetrafluorophenyl)phosphino}methane and [(η⁵-C₅Me₅)RhCl(μ-Cl)]₂. The structure of 2 has been determined by single crystal X-ray diffraction and compared to that of the pentafluorophenyl analogue [{η⁵,κP-C₅Me₄CH₂C₆F₄P(C₆F₅)-2-CH₂P(C₆F₅)₂}RhCl₂] (3). The presence of the trifluoromethyl groups, although not affecting the local structure about rhodium, disrupts the packing and consequently the structure of the two complexes is very different. The structure of 2 contains channels about 3-fold axes comprising fluoroaryl cavities separated by aliphatic constrictions arising from hexagonal rings of alternating enantiomers.