Treatment of a suspension of (IPr)AuCl [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidine] and AgSbF(6) (1:1) with isobutylene at room temperature for 12 h led to isolation of [(NHC)Au(eta(2)-H(2)C=CMe(2))](+) SbF(6)(-) (1a) in 98% yield, which was characterized by spectroscopy and X-ray crystallography. A number of cationic gold pi-alkene complexes were isolated employing a procedure similar to that used to isolate 1a, two of which were analyzed by X-ray crystallography. Spectroscopy, X-ray crystallography, and alkene binding studies were in accord with a gold-(pi-alkene) interaction dominated by sigma-donation from the alkene to gold.