Arene-rhodium(I) complexes with trimethyltetrafluorobenzobarrelene. Crystal structure of [Rh(Me3TFB)(1,4-C6H4Me2)]ClO4

The preparation of arene-rhodium(I) complexes of the general formula Rh(Me₃TFB)PhBPh₃ and [Rh(Me₃TFB)(arene)]ClO₄ (Me₃TFB = trimethyltetrafluorobenzobarrelene; arene = C₆H_6?nMe_n (n = 0, 1, 2, 3, 4 or 6); C₆H_6?nX_n (X = F, n = 2 or 6; X = Cl, n = 1 or 2) are described. For arenes of the type C₆H_6?nX_n the dissociation of the coordinated arene (studied by NMR spectroscopy in deuteroacetone) is complete, but for arenes of the type C₆H_6?nMe_n it decreases with increasing methyl substitution in the arene ligand.The crystal structure of [Rh(Me₃TFB)(1,4-C₆H₄Me₂)]ClO₄ has been determined by X-ray diffraction. The compound crystallizes in the Pbca space group, with lattice periodicities of 17.7393(4), 15.7816(3) and 16.0071(3) Å. δR-analysis, for the 3953 total recorded reflections, support the refinement carried out to a final R-value of 0.062. The bonding of the arene to the rhodium is η⁶, with the ring slightly puckered to give a distorted skew conformation.