Reactivity of [Cp*Rh(η6-C6H3NH2-2,6-i-Pr2)](OTf)2 toward phosphines and alkynes

The cationic aniline complex [Cp*Rh(eta(6)-2,6-(Me2CH)(2)C6H3NH2)](OTf)(2) (1) was prepared from either [Cp*Rh eta(2) -NO3)(eta(1)-OTf)] or [Cp*Rh(OH2)(3)](OTf)(2) and 2,6-diisopropylaniline. Complex I underwent substitution with phosphines or phosphites, indicating the labile character of the eta(6)-aniline ligand. Complex 1 mediated cycloaddition reactions of several alkynes in refluxing ethanol: the [2 + 2] dimerization for Ph-C equivalent to C-Ph and the [2 + 2 + 1] trimerization for Ph-C equivalent to C-H and CH3C6H4-C equivalent to C-H. The unexpected cyclobutadiene complex [Cp*Rh(eta(4)-C-4(C(O)CH3)(2)H(SiMe3))] was obtained from complex 1 and MeSi-C equivalent to C-C equivalent to C-SiMe3 and structurally characterized by X-ray diffraction. (c) 2006 Elsevier B.V. All rights reserved.