trans-[Rh(P(4-biphenyl)₃)₂(CO)Cl] (1): A J. Young’s Flask was charged with [Rh(CO)₂Cl]₂ (30 mg, 0.077 mmol) and P(4-biphenyl)₃ (151 mg, 0.309 mmol), and CH₂Cl₂ (4 mL) added at room temperature. The reaction mixture was stirred for 5 minutes and the solvent removed in vacuo. The resulting yellow powder was washed with pentane (2 x 3 mL), to afford the pure product as yellow solid (Yield = 168 mg, 95%). Crystals suitable for X-Ray diffraction analysis were grown by slow diffusion of pentane into a CH₂Cl₂ solution.

trans-[Ir(P(4-biphenyl)₃)₂(CO)Cl] (2): A J. Young’s Flask was charged with [Ir(COD)₂Cl]₂ (150 mg, 0.223 mmol) and P(4-biphenyl)₃ (438 mg, 0.892 mmol), and CH₂Cl₂ (4 mL) added. The reaction mixture was freeze-pump-thaw degassed, placed under an atmosphere of CO and stirred for 5 minutes. The solvent removed in vacuo and the resulting yellow powder was washed with pentane (2 x 3 mL). Crystals suitable for X-Ray diffraction analysis were grown by slow diffusion of pentane into a CH₂Cl₂ solution (Yield = 453 mg, 82%).

[Rh(P(4-biphenyl)₃)₂(CO)Cl] (1)

¹H NMR (600 MHz, CD₂Cl₂) δ 7.90-7.95 (m, 12H), 7.72 (d, J_HH = 8.0, 12H), 7.67 (d, J_HH = 7.3, 12H), 7.47 (t, J_HH = 7.3, 12H), 7.39 (t, J_HH = 7.3, 6H). ¹³C{¹H} NMR (151 MHz, CD₂Cl₂) δ 187.4 (dt, J_RhC = 75, J_PC = 16) 143.5 (s), 140.6 (s), 135.7 (t, J_PC = 7), 132.3 (t, J_PC = 23), 129.4 (s), 128.5 (s), 127.7 (s), 127.4 (t, J_PC = 5). ³¹P{¹H} NMR (243 MHz, CD₂Cl₂) δ 27.8 (J_RhP = 126). Anal. Calcd for C₇₃H₅₄ClOP₂Rh (1147.51 gmol^-1): C, 76.41; H, 4.74. Found: C, 76.37; H, 4.82. IR (CH₂Cl₂, cm^-1): ν(CO) 1978. The solid-state structure of this compound has been deposited with the Cambridge Crystallographic Data Centre under CCDC 1498191. 

 [Ir(P(4-biphenyl)₃)₂(CO)Cl] (2)

¹H NMR (400 MHz, CD₂Cl₂) δ 7.94 (br d, J_HH = 7.8, 12H), 7.67-7.82 (m, 24H), 7.37-7.55 (m, 18H). ¹³C{¹H} NMR (101 MHz, CD₂Cl₂) δ 172.2 (t, J_PC = 11), 143.7 (s), 140.5 (s), 135.9 (t, J_PC = 6), 131.6 (t, J_PC = 27), 129.5 (s), 128.5 (s), 127.8 (s), 127.4 (t, J_PC = 5). ³¹P{¹H} NMR (122 MHz, CD₂Cl₂) δ 22.8. Anal. Calcd for C₇₃H₅₄ClOP₂Ir (1236.82 gmol^-1): C, 70.89; H, 4.40. Found: C, 71.01; H, 4.60. IR (CH₂Cl₂, cm^-1): ν(CO) 1965. The solid-state structure of this compound has been deposited with the Cambridge Crystallographic Data Centre under CCDC 1498192.