Luminescent Iridium(I) Diethyldithiocarbamate Complexes: Synthesis, Structure, and Reactivity Including Stereoselective Hydrogen Oxidative Addition

A series of neutral Ir(I) complexes IrLL‘(Et 2 dtc) (L = L‘ = CO PPh 3, P(OPh) 3; L = CO, L‘ = PPh 3; 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)(PPh 3 )(Et 2 dtc) ( 3 ). Yellow-orange crystals of 3 (C 24 H 25 IrNOPS 2 ) are monoclinic, space group P 2 1 / n (no. 14), with a = 15.641(12) Å, b = 9.252(3) Å, c = 17.119(14) Å, β = 111.42(3)°, V = 2395.00 Å 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)(PPh 3 )(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(OPh 3 ) 2 )(Et 2 dtc), undergoes intramolecular C−H activation in benzene solution to form the ortho - metalated A benzene solution of Ir(CO)(PPh 3 )(Et 2 dtc) reacts readily with H 2, forming several different dihydride products having the formula IrH 2 (CO)(PPh 3 )(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 13 C resonance of the carbonyl ligand in submilligram samples of IrH 2 (PPh 3 )(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((C 6 F 5 ) 2 PCH 2 CH 2 P(C 6 F 5 ) 2 )(Et 2 dtc). Benzene solutions of Ir(CO)(PPh 3 )(Et 2 dtc) and Ir(dppe)(Et 2 dtc) react with molecular oxygen to form the stable adducts Ir(O 2 )(CO)(PPh 3 )(Et 2 dtc) and Ir(O 2 )(dppe)(Et 2 dtc), respectively, and both lose O 2 upon irradiation only. The complex Ir(CO)(PPh 3 )(Et 2 dtc) oxidatively adds CH 3 I to form the trans addition product Ir(CH 3 )(CO)(I)(PPh 3 )(Et 2 dtc).