Nickel and Palladium Complexes of Pyridine-Phosphine Ligands Bearing Aromatic Substituents and Their Behavior as Catalysts in Ethene Oligomerization

A Simple Manganese(I) Catalyst for the Efficient and Selective Hydrophosphination of Olefins with PH3, Primary, and Secondary Phosphanes

A tridentate ligand L with a P,NH,N donor motif was synthesized in few steps from commercially available precursors. Upon reaction with [MnBr(CO)5], an octahedral 18-electron complex [Mn(CO)3(L)]Br (1) is obtained in which L adopts a facial arrangement. After deprotonation of the NH group in the cationic complex unit, a neutral Mn(I) amido complex [Mn(CO)2(L-H)] (2) is formed under loss of CO. Rearrangement of L-H leads to a trigonal bipyramidal structure in which the P and N donor centers are in trans position. Further deprotonation of 2 results in a dep-blue anionic complex fragment [Mn(CO)2(L-2H)]- (3). DFT calculations and a QTAIM analysis show that the amido complex 2 contains a Mn-N bond with partial double bond character and 3 an aromatic MnN2C2 ring. The anion [Mn(CO)2(L-2H)]- reacts with Ph2PH to give a phosphido complex, which serves as phosphide transfer reagent to activated olefins. But the catalytic activity is low. However, the neutral amido complex 2 is an excellent catalyst and with loadings as low as 0.04 mol %, turn over frequencies of >40'000 h-1 can be achieved. Furthermore, secondary and primary alkyl phosphines as well as PH3 can be added in a catalytic hydrophosphination reaction to a wide range of activated olefins such as α,β-unsaturated aldehydes, ketones, esters, and nitriles. But also, vinyl pyridine and some styrene derivatives are converted into the corresponding phosphanes.

A cavity-shaped cis-chelating P,N ligand for highly selective nickel-catalysed ethylene dimerisation

The presence of a permethylated α-cyclodextrin (α-CD) cavity in a chelating P,N ligand promotes exclusive formation of 1 : 1 ligand/metal complexes. In MX₂ complexes, one of the two halido ligands is forced to reside inside the CD hollow while the second one is pointing outside. Unlike its cavity-free analogue, a Ni(II) complex of the CD ligand is a highly selective precatalyst for ethylene dimerisation (96% C₄ selectivity with up to 95% of 1-butene within the C₄ fraction).

Ni-Based Complexes in Selective Ethylene Oligomerization Processes

Linear alpha-olefins are widely used in the petrochemical industry and the world demand for these compounds increases annually. At present, the main method for producing linear alpha-olefins is the homogeneous catalytic ethylene oligomerization. This review presents modern nickel catalysts for this process, mainly systems for obtaining of one of the most demanded oligomer—1-butene—which is used for the production of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE). The dependence of the catalytic performance on the composition and the structure of the used activated complexes, the electronic and coordination states of the nickel center was considered.

t-BuOK-mediated reductive addition of P(O)–H compounds to terminal alkynes forming β-arylphosphine oxides

A novel and efficient t-BuOK-mediated reductive addition of P(O)–H compounds to terminal alkynes forming β-arylphosphine oxides was developed. This reaction may proceed via a tandem process involving regio-selective addition and subsequent transfer hydrogenation.

Ethylene oligomerization studies by nickel(ii) complexes chelated by (amino)pyridine ligands: experimental and density functional theory studies

Activation of (amino)pyridine nickel(ii) complexes 1–4 with either EtAlCl₂ or methylaluminoxane (MAO), produced active ethylene oligomerization catalysts to afford mostly butenes and hexenes and octenes as minor products.

Acetonitrile-[2-(1-{bis-[2,4,6-tris-(trifluoro-meth-yl)phen-yl]phosphan-yloxy}-1-methyl-eth-yl)pyridine]-methyl-palladium(II) hexa-fluoridoanti-monate dichloro-methane hemisolvate

In the title compound, [Pd(CH(3))(C(26)H(14)F(18)NOP)(C(2)H(3)N)][SbF(6)]·0.5CH(2)Cl(2), the Pd(2+) cation has a distorted square-planar environment, being coordinated by the acetonitrile [Pd-N = 2.078 (8) Å] and methyl [Pd-C = 2.052 (9) Å] groups and the bidentate ligand 2-(1-{bis-[2,4,6-tris-(trifluoro-meth-yl)phen-yl]phosphan-yloxy}-1-methyl-eth-yl)pyridine (L). In L, one -CF(3) group is rotationally disordered between two orientations in a 1:1 ratio. The solvent mol-ecule was treated as disordered between two positions related by an inversion center with occupancies fixed at 0.5. The crystal packing exhibits weak inter-molecular C-H⋯F contacts.