Search

Orange-red trinuclear nickel(II) complexes are obtained by reacting Ni(ClO4)2(H2O)6 with 3(5)-arylpyrazoles in the presence of a base. Herein, the diamagnetic nickel centers are coordinated in a square-pyramidal manner by four pyrazolato ligands, each of which bridges two nickel sites. The structurally unique complexes were investigated by NMR, IR, fluorescence, and X-ray spectroscopy. All seven compounds described here were structurally elucidated by single-crystal X-ray diffraction. With 3(5)-ferrocenylpyrazole as the substrate, a nonametallic system that possesses six redox-active ferrocenyl moieties was obtained. [ABSTRACT FROM AUTHOR]

A series of bimetallic silyl halido cuprates consisting of the new tripodal silicon-based metalloligand [κ3 N-Si(3,5-Me2pz)3Mo(CO)3]− is presented (pz=pyrazolyl). This metalloligand is straightforwardly accessible by reacting the ambidentate ligand tris(3,5-dimethylpyrazolyl)silanide ({Si(3,5-Me2pz)3}−) with [Mo(CO)3(η6-toluene)]. The compound features a fac-coordinated tripodal chelating ligand and an outward pointing, 'free' pyramidal silyl donor, which is easily accessible for a secondary coordination to other metal centers. Several bimetallic silyl halido cuprates of the general formula [CuX{μ-κ1 Si:κ3 N-Si(3,5-Me2pz)3Mo(CO)3}]− (X=Cl, Br, I) have been synthesized. The electronic and structural properties of these complexes were probed in detail by X-ray diffraction analysis, electrospray mass spectrometry, infrared-induced multiphoton dissociation studies, cyclic voltammetry, spectroelectrochemistry, gas-phase photoelectron spectroscopy, as well as UV/Vis and fluorescence spectroscopy. The heterobimetallic complexes contain linear two-coordinate copper(I) entities with the shortest silicon-copper distances reported so far. Oxidation of the anionic complexes in methylene chloride and acetonitrile solutions at ${E{{0\hfill \atop 1/2\hfill}}}$=−0.60 and −0.44 V (vs. ferrocene/ferrocenium (Fc/Fc+)), respectively, shows substantial reversibility. Based on various results obtained from different characterization methods, as well as density functional theory calculations, these oxidation events were attributed to the Mo0/MoI redox couple. [ABSTRACT FROM AUTHOR]