ExperimentalGeneral Remarks. All manipulations were performed in air, except where otherwise noted. The solvents thf and hexane (analytical grade) were freshly distilled from sodium/potassium alloy, dichloromethane was distilled from calcium hydride, the other solvents (acetonitrile, diethylether, acetone) were used as purchased. Deuterated solvents for NMR measurements were distilled from the appropriate drying agents under N 2 immediately prior to use following standard literature methods. 15 Air-sensitive compounds were stored and weighed in a glovebox. The reagents 1,2-dibromoethane, 1,3dibromopropane, 1,4-diiodobutane, 2,6-dimethylaniline, 2,4,6-trimethylaniline, 2,6-diisopropylaniline, triethylorthoformate, sodium tetrafluoroborate, and potassium bis(trimethylsilyl)amide were used as received. 1 H and 13 C NMR spectra were obtained on Bruker Avance AMX 400, 500 or Jeol Eclipse 300 spectrometers. The chemical shifts are given as dimensionless values and are frequency referenced relative to TMS. Coupling constants J are given in hertz (Hz) as positive values regardless of their real individual signs. Abbreviations used: st = septet, br = broad. Mass spectra (MS) and high-resolution mass spectra (HRMS) were obtained in positive electrospray (ES) mode unless otherwise reported, on a Waters Q-TOF micromass spectrometer. 1,3-Bis-(2,4,6-trimethylphenyl)-4,5,6,7-tetrahydro-3H-[1,3]diazepin-1-ium iodide, 7-Mes•HI. The reaction was performed on a 71.0 mmol scale of amidine (19.90 g), 5.00 g of K 2 CO 3 (36.0 mmol) and 22.00 g of 1,4-diiodobutane (71.0 mmol) in 1 L of acetonitrile. The solution was heated under reflux for 5 hours to yield 29.20 g (63.0 mmol, 89%) of white, crystalline material. 1,3-Bis-(2,6-dimethylphenyl)-4,5,6,7-tetrahydro-3H-[1,3]diazepin-1-ium iodide, 7-Xyl•HI. The reaction was performed on a 43.3 mmol scale of amidine (10.93 g), 5.8 mL of 1,4-diiodobutane (13.63 g, 44 mmol), 3.01 g of K 2 CO 3 (22.5 mmol) in 0.5 L of acetonitrile. The solution was heated under reflux for 5 hours to yield 14.85 g (34.2 mmol, 79%) of white, crystalline material. 1,3-Bis-(2,6-diisopropylphenyl)-4,5,6,7-tetrahydro-3H-[1,3]diazepin-1-ium iodide, 7-Pr i •HI. The reaction was performed on a 11.0 mmol scale of amidine (4.00 g), 0.78 g of K 2 CO 3 (5.6 mmol), 1.6 mL of 1,4-diiodobutane (3.76 g, 12.1 mmol) in 400 mL of acetonitrile. The solution was heated under reflux for 17 hours to yield 3.87 g (7.1 mmol, 64%) of white, crystalline material. 2,4-Bis-(2,4,6-trimethylphenyl)-4,5-dihydro-1H-benzo[e][1,3]diazepin-2-ium bromide, Xyl7-Mes•HBr. The reaction was performed on a 35.8 mmol scale of amidine (10.03 g), 36.0 mmol of , 'dibromo-o-xylene (9.49 g), 2.49 g of K 2 CO 3 (18.0 mmol) in 0.5 L of acetonitrile. The solution was heated under reflux for 5 hours to yield 12.42 g (26.2 mmol, 73%) of white, crystalline material. 1 H

The synthesis of the novel seven-membered N-heterocyclic carbene (NHC) 1,3-dicyclohexyl-1,3diazepan-2-ylidene (3) and its 5,6-dioxolane derivative 4 is reported and their coordination chemistry with Rh(I), Ir(I), and Pt(0) discussed. The M(cod)(3)Cl, where M ) Rh and Ir, complexes display a high rotation barrier at room temperature about the M-C NHC bond, whereas for the M(CO) 2 ( 3)Cl and Pt-(nbe) 2 (3) complexes rapid rotation of the carbene ligand is observed at ambient temperature. The infrared ν(CO) values of the Rh(I) and Ir(I) derivatives M(CO) 2 (3)Cl give a measure of the donor ability of the new carbene ligands. The crystal structures of the amidinium salts 3‚HPF 6 and 4‚HPF 6 together with those of M(cod)(3)Cl [M ) Rh, Ir], Ir(cod)(4)Br, Ir(CO) 2 (3)Cl, and Pt(nbe) 2 (3) are reported. Both the salts and the coordinated carbene ligands exhibit extremely large NCN angles; for the complexes the angles are in the range 115.5(3)°[Pt(3)] to 122(11)°[Ir(4)].

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The synthesis of new functionalised 6- and 7-membered NHC (N-heterocyclic carbene) precursors bearing anisidyl or pyridine N-substituents, both symmetrically and non-symmetrically substituted is reported. Their corresponding rhodium(i) and iridium(i) complexes, M(COD)(NHC)Cl, were also prepared and characterised. The unusual Rh(iii)/Rh(i) salt, [Rh(eta(2)-NHC-py)(2)Cl(2)][Rh(COD)Cl(2)], was obtained with one of the pyridyl-functionalised NHC ligands. Single-crystal X-ray analyses have been obtained for the majority of the complexes and NHC salts. The activity of these complexes was tested in the hydrogenation of a range of substrates with molecular hydrogen, including 1-cyclooctadiene and 2-methyl styrene, where they show enhanced activity and stability in comparison to non-functionalised NHC analogues, operating under exceptionally mild conditions (ambient temperature and atmospheric pressure).

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The performances of a number of RhI and IrI complexes of type [M(NHC)(COD)Cl] in the transfer hydrogenation of ketones were tested under a variety of reaction conditions, and with a variety of substrates, allowing comparison of Rh‐ and Ir‐NHC complexes, and also comparison of the influence of the NHC ligand on catalytic performance. Notably, of the RhI and IrI complexes with symmetrically substituted NHCs only those bearing cyclohexyl substituents were active, with RhI complexes of saturated 5‐, 6‐ and 7‐NHCs with N‐Mes substituents, [Rh(5,6,7‐Mes)(COD)Cl], showing no activity in transfer hydrogenation under the test conditions. RhI and IrI complexes of unsymmetrical o‐methoxyphenyl donor‐functionalised NHCs (df‐NHC) with differing carbene ring sizes were also tested in transfer hydrogenations, with the RhI complexes displaying no catalytic activity. However, the corresponding df‐NHC IrI complexes were found to be extremely effective catalysts. Catalyst tests also demonstrated the excellent stability of these complexes.

A Concise Synthesis of a Rigid Isomannide-Based Diphosphine Ligand and Structural Characterization of an Alkoxyphosphonium Intermediate. -The synthesis of the novel C2 diphosphine ligand DDPPM is described and its performance in the asymmetric olefin reduction is investigated. -(CARCEDO, C.; DERVISI*, A.; FALLIS, I. A.; OOI, L.; MALIK, K. M. A.; Chem.

The synthesis of the benzyl phosphinothioether derivatives Ph(2)PCH(2)CH(Et)SR and their corresponding palladium complexes are reported, where R = CH(2)Ph, R = CH(2)-3,5-Me-C(6)H(3) and R = 1-CH(2)C(10)H(7)(5). Crystallographic data obtained for the complexes Pd(3)Cl(2) and Pd(4)Cl(2) show intra- and inter-molecular pi-pi interactions between the aromatic rings on the P and S substituents, and NOE experiments for Pd(4)Cl(2) show that these interactions persist in solution. The performance of the phosphinothioether palladium complexes in aryl-aryl cross-coupling reactions is compared with that of the corresponding complex of the parent phosphinothiolato ligand Ph(2)PCH(2)CH(Et)S(-)(1). High turnover numbers up to 2000000 are reported for the coupling of bromobenzene, using the palladium dimer [Pd(1)I](2) as the catalyst precursor. Kinetic studies show a linear dependence of the reaction on catalyst loading. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported.