The cationic aniline complex [Cp ∗ Rh(η 6 -2,6-(Me 2 CH) 2 C 6 H 3 NH 2 )](OTf) 2 (1) was prepared from either [Cp ∗ Rh(η 2 -NO 3 )(η 1 -OTf)] or [Cp ∗ Rh(OH 2 ) 3 ](OTf) 2 and 2,6-diisopropylaniline. Complex 1 underwent substitution with phosphines or phosphites, indicating the labile character of the η 6 -aniline ligand. Complex 1 mediated cycloaddition reactions of several alkynes in refluxing ethanol: the [2+2] dimerization for PhCCPh and the [2+2+1] trimerization for PhCCH and CH 3 C 6 H 4 CCH. The unexpected cyclobutadiene complex [Cp ∗ Rh(η 4 -C 4 (C(O)CH 3 ) 2 H(SiMe 3 ))] was obtained from complex 1 and Me 3 SiCCCCSiMe 3 and structurally characterized by X-ray diffraction.