η 3 -Allyliridium(III) complexes Cp*Ir(η 3 -CHPhCHCH 2 )(-CtC-t-Bu) (2), Cp*Ir(η 3 -CHPh-CHCH-CHdCH(t-Bu))Cl (3H), Cp*Ir(η 3 -CHPhCHCH-CHdCMe(t-Bu))I (3Me), [Cp*Ir(η 3 -CHPhCHCH-CHdCMe(t-Bu))(NCMe)] + (4), and Cp*Ir(η 3 -CHPhCHCH-CHdCMe(t-Bu))-(-CtC-t-Bu′) (5) have been prepared from the reactions of [Cp*Ir(η 3 -CHPhCHCH 2 )-(NCMe)] + (1) with H-CtC-t-Bu (in the presence of NEt 3 ), HCl, and MeI. The crystal structures of 2 and 5 have been determined by X-ray diffraction data analyses. Reactions of 3 and 5 with HCl produce trans,trans-1,3-pentadienes, PhCHdCHCHdCHCH 2 (t-Bu) (6H) and PhCHdCHCHdCHCHMe(t-Bu) (6Me), and cis,trans,trans-1,3,5-heptatriene, (t-Bu′)-CHdCHC(Ph)dCHCHdCHCHMe(t-Bu) (8), respectively. ResultsSynthesis of Metal Complexes. Alkynyl η 3 -allyl complex Cp*Ir(η 3 -CHPhCHCH 2 )(-CtC-t-Bu) (2) is prepared by replacing MeCN with -CtC-t-Bu from the reaction of H-CtC-t-Bu with [Cp*Ir(η 3 -CHPhCHCH 2 )-(NCMe)] + (1) in the presence of NEt 3 and characterized by spectral and elemental analysis data and also by crystal structure determination by X-ray diffraction analysis (Figure 1). The η 3 -allyl group of 2 in the solid state is best described as a symmetric η 3 -allyl ligand since the C-C distances (C(11)-C(12) 1.44(2) Å; C(12)-C(13) 1.38(2) Å) in the η 3 -allyl group are not much different from each other. 1 H NMR spectrum of 2 in CDCl 3 shows typical signals due to an η 3 -allyl lignd. 3a,7 Complex 2 reacts with HCl and MeI to give the η 3pentadienyl-iridium complexes Cp*Ir(η 3 -CHPhCHCH-CHdCH(t-Bu))Cl (3H) and Cp*Ir(η 3 -CHPhCHCH-CHd CMe(t-Bu))I (3Me), respectively (see Scheme 1). The Iin 3Me is readily replaced by MeCN to give [Cp*Ir(η 3 -CHPhCHCH-CHdCMe(t-Bu))(NCMe)] + (4), which further undergoes substitution reaction of MeCN with another -CtC-t-Bu′ group to produce Cp*Ir(η 3 -CHPh-CHCH-CHdCMe(t-Bu))(-CtC-t-Bu′) (5) in the presence of NEt 3 (see Scheme 1).These η 3 -pentadienyl-iridium complexes 3-5 have been unambiguously characterized by spectral and elemental analysis data and also by crystal structure