C.F. Nobile

Oxidative carbonylation of aniline catalyzed by Pd(II)-2,2'-bipyridyl complex intercalated in α-zirconium-phosphate

Abstract Palladium(II) and palladium(II)-copper(II) complexes (with N-donor ligands intercalated between the layers of α-zirconium phosphate) have been employed in the oxidative carbonylation of aniline. The catalytic activity of the materials has been studied together with the properties of α-zirconium phosphate as a supporting agent. Their very low activity observed in an initial induction period slowly increases to more marked levels in mild working conditions (80 °C, atmospheric pressure); in more drastic conditions diphenylurea and methyl carbamate are produced in a non-selective way due to a concomitant oxidation of aniline. By pre-heating the materials at 130 °C under CO or CO/O2, an increase of the catalytic activity is obtained, and the treated systems are able to catalyze selectively the carbonylation of aniline in mild conditions. By submitting the pretreated systems to a series of catalytic cycles and by re-employing the same catalyst in each cycle, a decrease in activity is observed until complete deactivation of the catalyst, when Pd is almost completely eliminated by the solid. On the basis of the analysis of the pretreated sample before and after deactivation, this behaviour is ascribed to migration of the Pd from the inner layers to the surface of the solid matrix and to its subsequent solubilization in the reaction medium.

Carbamoyl and alkoxycarbonyl complexes of palladium(II) and platinum(II)

Abstract Carbamoyl and alkoxycarbonyl complexes of palladium(II) and platinum(II) of the type M(pnp)(CONHR)Cl (pnp = 2,6-bis(diphenylphosphinomethyl)pyridine; M Pd, R  C6H5, p-CH3C6H4, p-CH3OC6H4, C6H11, t-Bu; M  Pt, R  C6H5), Pd(pnp)[CON(Pr)2]Cl (Pr = propyl), M(pnp)(COOR)Cl (M  Pd, R  C6H5, CH3; M  Pt, R  CH3), Pd(pnp)(COOCH3)2 result from reaction of M(pnp)Cl2 with carbon monoxide and amines or alkoxides at room temperature and atmospheric pressure. The carbamoyl complexes react with bases to give urethane or diphenylurea depending upon the experimental conditions.

Synthesis and reactivity toward gas molecules of chloro 2,6-di(diphenylphosphinomethyl)pyridine rhodium(I)

Abstract The synthesis of the title compound and of its adducts with O 2 , CO, CO 2 , SO 2 , tertiary phosphines is described. The reactions of the dioxygen adduct with sulfur dioxide and carbon monoxide are also reported.

Oxidative carbonylation of aliphatic amines catalysed by nickel-complexes

Abstract The catalytic activity of some nickel-complexes in the dioxygen-induced carbonylation of amines has been studied. N,N′-oxamides expected on the basis of a previous report. The study of the reaction mechanism shows that amines are carbonylated in a reductive step, during which either ureas or oxamides can be obtained depending on the amount of water present. When dioxygen is used as the oxidant the oxidative step produces water, which promotes the urea formation. The oxygen is also responsible for the low yields owing to a side reaction involving amine oxidation. These conclusions were confirmed when the carbonylations were carried out under pseudo-catalysis conditions, or when oxidants which do not produce water in the oxidative step were used.

Rhodium and iridium complexes containing nitrosoarene ligands

Abstract A number of new nitrosoarene complexes of rhodium(I) and iridium(I) have been prepared, and characterized by elemental analysis, IR spectroscopy and 1H NMR spectroscopy. Some reactions of the complexes have been studied.

Olefin ligands. Syntheses and structures of 2,6-diallylpyridine (DAP) complexes of rhodium(I); crystal structures of [Rh(COD)(DAP)][RhCl2(COD)] and [Rh(COD)(DAP)][CuCl2]

Abstract The olefinic ligand 2,6-diallylpyridine (DAP) has been shown to react with various rhodium(I) compounds to give complexes of the type [RhCl(DAP)] n , RhCl(L)(DAP) (L = CO, PPh 3 ), [Rh(diene)(DAP)]Y (diene = cycloocta-1,5-diene (COD), bicyclo[2.2.1]hepta-2,5-diene (NBD); Y = [RhCl 2 (diene)], [CuCl 2 ], ClO 4 ). These complexes have been characterised by chemical and spectroscopic means. In addition, the crystal structures of [Rh(COD)(DAP)][RhCl 2 (COD)] ( 1 ) and [Rh(COD)(DAP)][CuCl 2 ] ( 2 ) have been determined by X-ray methods. Crystal of 1 are triclinic, space group P 1 , with Z = 2 in a unit cell of dimensions a 10.481(4), b 13.041(4), c 10.456(4) A, α 106.77(2), β 112.10(2), γ 79.57(1)°. Crystals of 2 are monoclinic, space group P 2 1 / c , with Z = 4 in a unit cell of dimension a 14.303(8), b 10.453(5), c 13.412(6) A, β 110.95(4)°. Both structures were solved from diffractometer data by direct and Fourier methods and refined by blocked full-matrix least-squares to R = 0.0316 (2204 observed reflections) for 1 and by full matrix least-squares to R = 0.0545 (1897 observed reflections) for 2 . The crystals consist of cationic [Rh(COD)(DAP)] + and anionic [Rh(COD)Cl 2 ] − ( 1 ) and [CuCl 2 ] − ( 2 ) complexes. The cations are similar in the two compounds, and the coordination around the Rh I atoms can be described as trigonal bipyramidal, with a “short” RhN axial bond and four η 2 -CC olefinic interactions. The DAP acts as a tridentate ligand.

Tetraco-ordinated complexes of cobalt(I)

Abstract The preparation and properties of cobalt(I) complexes of general formula Co(dp) 2 X [dp = C 2 H 4 (PPh 2 ) 2 ; X = Br, ClO 4 , BPh 4 ] are reported. The bromide derivative is tetraco-ordinated in polar solvents and pentaco-ordinated in non polar solvents, while the perchlorate and the tetraphenylborate are tetraco-ordinated both in solution and in the solid state. These compounds easily add hydrogen, carbon monoxide and sulfur dioxide. The reactions with benzoyl chloride and nitrogen monoxide are also reported.

Carbon dioxide-transition metal complexes. IV. New Ni(0)CO2 complexes with chelating diphosphines: influence of PNiP angle on complex stabilities

Abstract The reaction between Ni(0) complexes (dp) (dp = 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(dicyclohexylphosphino)propane, 1,4-bis(dicyclohexylphosphino)butane; dcpe, dcpp, dcpb, respectively) and carbon dioxide is described. The influence of the PNiP bond angle on the stability of the corresponding adducts is discussed. The reactions of Ni(dcpp)CO2 and Ni(dcpb)CO2 with dioxygen are also described.

2,6-Bis(diphenylphosphinomethyl)pyridine complexes of nickel(II), cobalt(II), iron(II)

Abstract Some new 2,6-bis(diphenylphosphinomethyl)pyridine (pnp) complexes of nickel(II), cobalt(II) and iron(II) were prepared and their physical properties were determined and compared with those of some previously described nickel(II) complexes. A pentaco-ordinate molecular structure (distorted tirgonal bipyramidal), instead of the previous square-planar, is now suggested for [Ni(pnp) 2 ] 2+ . For Ni(pnp)-(NCS) 2 , previously described as a mixture of low-spin and high-spin forms of a five-co-ordinated molecule, the interallogon formulation [Ni(pnp)NCS] [Ni(pnp)-(NCS) 3 ], which receives strong support from the experimental data, is suggested. The hexa-co-ordinated Ni(pnp)(NO 3 ) 2 , the penta-co-ordinated high spin Co(pnp)(NO 3 ) 2 and Fe(pnp)(NO 3 ) 2 , and the hexaco-ordinated low-spin [Co(pnp) 2 ](ClO 4 ) 2 and [Fe(pnp) 2 ](ClO 4 ) 2 are also described. The equilibrium constant for the hydration reaction of Ni(pnp)Cl 2 in n-BuOHH 2 O solution is determined.

New nickel(O) complexes with bulky diphosphine ligands

Abstract The synthesis and characterization of new complexes of formula Ni(dp), Ni(dp)C 7 H 8 (dp = 1,2-bis(dicyclohexylphosphino)ethane [dcpe]; 1,3-bis(dicyclohexylphosphino)propane [dcpp]; 1,4-bis(dicyclohexylphosphino)butane [dcpb]),Ni 2 (dcpe) 3 , Ni 2 (dcpb) 3 , Ni(depe) 2 and Ni(depe) 2 (depe = 1,2-bis(diethylphosphino)ethane) are described. The electronic spectra of these complexes are discussed.