Investigating intermediates in the CCC–NHC pincer ligand metalation/transmetalation to Rh sequence, an improved stoichiometric synthesis of CCC–NHC pincer Rh complexes

Redox–Transmetalation Reactions: Easy Access to Homo- and Heterodimetallic d8,d10 Complexes

“…NMR spectra were recorded on Bruker AV-300, AV-400 and AV-500 spectrometers operating at 300.13, 400.13, and 500.13 MHz respectively, for 1 H. Chemical shifts are reported in ppm and referenced to SiMe 4 , using the internal signal of deuterated solvent as the reference ( 1 H and 13 C). 31 P NMR chemical shifts are reported relative to external 85% H 3 PO 4 . For the labeling of protons and carbons, see Figure 11.…”

“…1 H NMR (500.13 MHz, CD 2 Cl 2 , 25 °C): δ = 8.52 (br d, 3 J H,H = 4.1 Hz, 1H; H A6 ), 7.96 (d, 3 J H,H = 7.9 Hz, 1H; H A3 ), 7.62 (td, 3 J H,H = 7.7, 4 J H,H = 1.9 Hz, 1H; H A4 ), 7.39−7.27 (m, 16H; PPh 3 + H B6 ), 7.14 (ddd, 3 J H,H = 7.5 Hz, 3 J H,H = 4.9 Hz, 4 J H,H = 1.2 Hz, 1H; H A5 ), 6.88 (td, 3 J H,H = 7.8 Hz, 4 J H,H = 1.6 Hz, 1H; H B4 ), 6.80 (ddt, 3 J H,H = 7.3 Hz, 3 J H,H = 5.6 Hz, 4 J H,H = 1.3 Hz, 5 J H,P = 1.3 Hz, 1H; H B5 ), 5.26 (d, 3 J H,H = 8.0 Hz, 1H; H B3 ), 4.85 (d, 3 J H,P = 3.1 Hz, 1H; HC�N), 4.66 (br s, 2H; cod-HC�), 4.25 (δ A , 1H) and 4.13 (δ B , 1H) (ABX spin system (X = P), 2 J A,B = 15.6 Hz, 4 J A,X = 6.5 Hz, 4 J B,X = 3.5 Hz; H 2 C−N), 4.13 (br s, 2H; cod-HC = ), 2.53 (m, 4H; cod-CH 2 exo ), 1.99 (m, 2H; cod-CH 2 endo ), 1.89 (m, 2H; cod-CH 2 endo ). 31 P{ 1 H} NMR (202.46 MHz, CD 2 Cl 2 , 25 °C): δ = 30.8 (s, PPh 3 ). 13 [(PPh 3 )(Cl)Ni 0 (μ-bpi)Ni ΙΙ (Cl)](10) was prepared as described for 4 starting from [{Ir(μ-OMe)(cod)} 2 ] (75.0 mg, 0.113 mmol), bpa (21.1 μL, 0.113 mmol), and [Ni(Cl) 2 (PPh 3 ) 2 ] (148.0 mg, 0.226 mmol).…”

“…The former has been extensively used in rhodium and iridium chemistry, whereas the latter has been frequently employed to prepare gold complexes . Other less common bridging ligands include oxacyclohexadiene, phosphino trisilanes, diphosphine imines, and CNC-type pincers …”

“…27 Other less common bridging ligands include oxacyclohexadiene, 28 phosphino trisilanes, 29 diphosphine imines, 30 and CNC-type pincers. 31 In this context, the imine PyCH�N−CH 2 Py (Py = 2pyridyl, bpi) has demonstrated its capability to function as a heteroditopic ligand suitable to create two separate compartments to host different metallic fragments. For example, the complex [(cod)(Cl)Ir Ι (μ-bpi)Ir Ι (cod)]PF 6 features a squareplanar iridium center bonded to one pyridine and the imine nitrogen, whereas the second pyridine and the π-HC�N bond accommodate a pentacoordinated 'Ir(cod)(Cl)' moiety.…”

“…MHz, CD 2 Cl 2 , 25 °C): δ = 8.82 (br d, 3 J H,H = 5.7 Hz, 1H; H A6 ), 8.46 (dd, 3 J H,H = 5.6 Hz,4 J H,H = 1.2 Hz, 1H; H B6 ), 7.91 (td, 3 J H,H = 7.7 Hz,4 J H,H = 1.6 Hz, 1H; H A4 ), 7.47 (d, 3 J H,H = 8.0 Hz, 1H; H A3 ), 7.43 (dd, 3 J H,P = 11.1 Hz, 3 J H,H = 6.7 Hz, 6H; o Ph 3 P), 7.41 (t, 3 J H,H = 7.8 Hz, 3H; p Ph 3 P), 7.35 (m, 7H, m PPh 3 + H B5 ), 7.07 (td, 3 J H,H = 7.8 Hz,4 J H,H = 1.7 Hz, 1H; H B4 ), 6.96 (t, 3 J H,H = 6.6 Hz, 1H; H B5 ), 5.28 (d, 3 J H,H = 8.1 Hz, 1H; H B3 ), 4.90 (δ A , 1H) and 4.42 (δ B , 1H) (ABX spin system, X = P), 2 J A,B = 16.7 Hz,4 J A,X = 13.1 Hz,4 J B,X = 5.3 Hz; H 2 C−N), 4.84 (d, 3 J H,P = 3.8 Hz, 1H; HC�N) 31. P{ 1 H} NMR (202.46 MHz, CD 2 Cl 2 , 25 °C): δ = 31.8 (s, PPh 3 ) 13.…”