A series of neutral Ir(I) complexes IrLL'(Et(2)dtc) (L = L' = CO PPh3, P(OPh)(3); L = CO, L' = PPh3; L + L' = 1,2-bis(diphenylphosphino)ethane, 1,5-cyclooctadiene, 1,2-bis(di(pentafluorophenyl)phosphino)ethane; Et-2-dtc = N,N'-diethyldithiocarbamate) has been synthesized and characterized by NMR, IR, and electronic spectroscopies. The complexes show spectra consistent with a four-coordinate structure. A distorted square planar coordination geometry is confirmed by a single crystal structure determination of Ir(CO)(PPh3)(Et(2)dtc) (3). Yellow-orange crystals of 3 (C24H25IrNOPS2) are monoclinic, space group P2(1)/n (no. 14), with a 15.641(12) Angstrom, b = 9.252(3) Angstrom, c = 17.119(14) Angstrom, beta = 111.42(3)degrees, V = 2395.00 Angstrom(3), Z = 4, and final R = 0.029 (R-w = 0.031) for 3204 unique reflections. All of the complexes exhibit emission in the solid state and in frozen glass media at 77 K. Additionally, Ir(CO)(PPh3)(Et(2)dtc), Ir(dppe)(Et(2)dtc), and Ir(P(OPh)(3))(2)(Et(2)dtc) display emission in methylene chloride solutions at room temperature. The bis triphenylphosphite complex, Ir(P(OPh3)(2))(Et(2)dtc), undergoes intramolecular C-H activation in benzene solution to form the ortho-metalated product Ir(P(OPh)(2)(OC6H4))(H)(P(OPh)(3))(Et(2)dtc). A benzene solution of Ir(CO)(PPh3)(Et(2)dtc) reacts readily with H-2, forming several different dihydride products having the formula IrH2(CO)(PPh3)(Et(2)dtc), including an isomer with a kinetic preference for formation of 170:1 as determined using parahydrogen induced polarization (PHIP) at 300 K. A method is described for observing the C-13 resonance of the carbonyl ligand in submilligram samples of IrH2(PPh3)(CO)(Et(2)dtc) in under 2 min. The ligand exchange reactions of the two parahydrogen active isomers are also examined. PHIP is also observed in H-2 oxidative addition to Ir((C6F5)(2)-PCH2CH2P(C6F5)(2))(Et(2)dtc) Benzene solutions of Ir(CO)(PPh3)(Et(2)dtc) and Ir(dppe)(Et(2)dtc) react with molecular oxygen to form the stable adducts Ir(O-2)(CO)(PPh3)(Et(2)dtc) and Ir(O-2)(dppe)(Et(2)dtc), respectively, and both lose O-2 upon irradiation only. The complex Ir(CO)(PPh3)(Et(2)dtc) oxidatively adds CH3I to form the trans addition product Ir(CH3)(CO)(I) (PPh3) (Et(2)dtc).