Catalytic Ammonia Synthesis Mediated by Molybdenum Complexes with PNP Pincer Ligands: Influence of P/N Substituents and Molecular Mechanism.

Three molybdenum trihalogenido complexes supported by different PNP pincer ligands were synthesized and investigated regarding their activity towards catalytic N-to-NH conversion. The highest yields were obtained with the H-PNP ligand. The corresponding Mo(V)-nitrido complex also shows good catalytic activity.

Crystal structure of [{FeCl}(μ-PCP)] [PCP = 1,3-bis-(2-di-phenyl-phosphanyleth-yl)-3-imidazol-1-ium] with an unknown solvent.

The crystal structure of the title compound, bis-{μ-1,3-bis-[2-(di-phenyl-phosphan-yl)eth-yl]-1-imidazole-κ :'}bis-[tri-chlorido-iron(III)], [FeCl(CHNP)] or [{FeCl}(μ-PCP)] (PCP = CHNP), consists of dinuclear complexes that are located about centres of inversion. The Fe cation is in a distorted trigonal-bipyramidal coordination with three chloride ligands located in the trigonal plane and two P atoms of symmetry-related PCP ligands occupying the axial positions. Within the centrosymmetric complex, a pair of intra-molecular C-H⋯Cl hydrogen bonds between aromatic CH groups and chloride ligands are found.

Influence of a Metal Substrate on Small-Molecule Activation Mediated by a Surface-Adsorbed Complex.

Activating small molecules with transition metal complexes adsorbed on metal surfaces is a novel approach combining aspects of homogeneous and heterogeneous catalysis. In order to study the influence of an Au(111) substrate on the activation of the small-molecule ligand carbon monoxide, a molybdenum tricarbonyl complex containing a PN P pincer ligand was synthesized and investigated in the bulk, in solution, and adsorbed on an Au(111) surface. By means of a platform approach, a perpendicular orientation of the molybdenum complex was achieved and confirmed by IRRAS and NEXAFS.

Molybdenum complexes supported by mixed NHC/phosphine ligands: activation of N2 and reaction with P(OMe)3 to the first meta-phosphite complex.

Molybdenum(0) dinitrogen complexes, supported by the mixed NHC/phosphine pincer ligand PCP, exhibit an extreme activation of the N2 ligand due to a very π-electron-rich metal center. The low thermal stability of these compounds can be increased using phosphites instead of phosphines as coligands. Through an amalgam reduction of [MoCl3(PCP)] in the presence of trimethyl phosphite and N2 the highly activated and room-temperature stable dinitrogen complex [Mo(N2)(PCP)(P(OMe)3)2] is obtained.