The iridium(III) complexes containing (2-aminoethyl)dimethylphosphine (edmp) or (2-aminoethyl)diphenylphosphine (edpp) were prepared. Crystal structures of fac-[Ir(edmp)₃]Cl₃·5H₂O (2), trans(Cl,Cl),cis(P,P)-[IrCl₂(edpp)₂]BF₄ (3), and Δ(lel₃)- and Λ(ob₃)-[Ir(R,R-chxn)₃](NO₃)₃·3H₂O (4 and 5; chxn = trans-1,2-cyclohexanediamine) were determined by single-crystal X-ray diffraction. Crystal data and final R values are: for 2, FW = 703.7, triclinic, , a = 11.718(2), b = 13.199(1), c = 9.482(1) Å, α = 91.44(1), β = 105.86(1), γ = 90.53(1)°, V = 1410.0(2) ų, D_x = 1.66 Mg m⁻³, and Z = 2, R = 0.039 for 5410 reflections. For 3, FW = 808.5, triclinic, , a = 11.465(1), b = 13.694(1), c = 10.049(1) Å, α = 94.764(6), β = 92.197(8), γ = 102.807(8)°, V = 1530.5(2) ų, D_x = 1.75 Mg m⁻³, and Z = 2, R = 0.035 for 5978 reflections. For 4, FW = 774.9, hexagonal, P6₃, a = 13.005(1), c = 10.221(2) Å, V = 1497.1(3) ų, D_m = 1.71(2), D_x = 1.72 Mg m⁻³, and Z = 2, R = 0.020 for 1063 reflections. For 5, hexagonal, FW = 774.9, P6₃, a = 13.359(1), c = 9.848(2) Å, V = 1522.0(3) ų, D_m = 1.70(2), D_x = 1.69Mg m⁻³, and Z = 2, R = 0.015 for 1105 reflections. The average Ir–N bond length of 2.167(6) Å in 2 is longer by 0.077(6) Å than those in 4 and 5. The structural data of the corresponding cobalt(III) and rhodium(III) complexes show that the order of the strength of the trans influence of the –PMe₂ group in edmp is Co^III < Ir^III < Rh^III. In 3, the elongation of the metal–nitrogen bond length by the trans influence of the –PPh₂ group in edpp is smaller than that of the –PMe₂ group in 2, and the elongation is nearly the same as those in the corresponding cobalt(III) and rhodium(III) complexes. The absorption spectra of the two series of complexes, fac-[M(edmp)₃]³⁺ and trans(Cl,Cl),cis(P,P)-[MCl₂(edpp)₂]⁺ (M = Co^III, Rh^III, and Ir^III) are compared and Shimura's spectrochemical parameters for iridium(III) are discussed.