Computational Characterization of Redox Non-Innocence in Cobalt-Bis(Diaryldithiolene)-Catalyzed Proton Reduction.

Localized orbital bonding analysis (LOBA) was employed to probe the oxidation state in cobalt-bis(diaryldithiolene)-catalyzed proton reduction in nonaqueous media. LOBA calculations provide both the oxidation state and chemically intuitive views of bonding in cobalt-bis(diaryldithiolene) species and therefore allow characterization of the role of the redox non-innocent dithiolene ligand. LOBA results show that the reduction of the monoanion species [1Br](-) is metal-centered and gives a cobalt(II) ion species, [1Br](2-), coordinated to two dianionic ene-1,2-dithiolates.

Mechanism of the electrocatalytic reduction of protons with diaryldithiolene cobalt complexes.

A series of dimeric cobalt-diaryldithiolene complexes [Co(S2C2Ar2)2]2, possessing various aryl para substituents (OMe, F, Cl, and Br), were studied as electrocatalysts for proton reduction in nonaqueous media, in an effort to correlate dithiolene donor strength with catalyst activity. Cyclic voltammetry data acquired for the cobalt-diaryldithiolene dimers guided the isolation of chemically reduced monoanionic ([Co(S2C2Ar2)2](-)) and dianionic ([Co(S2C2Ar2)2](2-)) monomers. The potassium and tetrabutylammonium salts of dianionic cobalt-diaryldithiolene complexes have been characterized by single crystal X-ray crystallography.

Ligand effects on the overpotential for dioxygen reduction by tris(2-pyridylmethyl)amine derivatives.

A series of copper complexes based on the tris(2-pyridylmethyl)amine (TPA) ligand are examined for their oxygen reduction reaction (ORR) activity. Increasing the potential of the Cu(I/II) couple from 0.23 V vs RHE for [Cu(TPA)(L)](2+) to 0.

Influence of second coordination sphere hydroxyl groups on the reactivity of copper(I) complexes.

We report the enhanced reactivity of hydroxyl substituted CuN(3)(+) derivatives, where N(3) = tris(picolinyl)methane (tripic) and related derivatives, upon deprotonation of the O-H functionality. The work capitalizes on new methodology for incorporating hydroxyl groups into the second coordination sphere of copper centers. The key synthetic methodology relies on Pd-catalyzed coupling reactions of dilithiated 6-methyl-2-pyridone with bromopyridyl derivatives.

Dioxygen and hydrogen peroxide reduction with hemocyanin model complexes.

Three copper polypyridyl complexes were examined as electrocatalysts for the oxygen reduction reaction (ORR): a Cu-N(3) complex, [Cu-[tris(6-methylpyridin-2-yl)methane]-(NCMe)]PF(6) (1); a related Cu(2)N(6) derivative, [Cu(2)-[1,2-bis(6-(bis(6-methylpyridin-2-yl)methyl)pyridin-2-yl)ethane]-(NCMe)(2)](PF(6))(2) (2); and the CuN(4) species [Cu-[tris(pyridin-2-ylmethyl)amine]](ClO(4))(2) [3](ClO(4))(2). Compared to other copper complexes, [3](ClO(4))(2) exhibits the highest reported ORR onset potential for a Cu complex of 0.53 V vs reversible hydrogen electrode at pH 1.

Coordination chemistry of the soft chiral Lewis acid [Cp*Ir(TsDPEN)]+.

The paper surveys the binding of anions to the unsaturated 16e Lewis acid [Cp*Ir(TsDPEN)](+) ([1H](+)), where TsDPEN is racemic H(2)NCHPhCHPhNTs(-). The derivatives Cp*IrX(TsDPEN) were characterized crystallographically for X(-) = CN(-), Me(C═NH)S(-), NO(2)(-), 2-pyridonate, and 0.5 MoS(4)(2-).

Air- and water-stable catalysts for hydroamination/cyclization. Synthesis and application of CCC-NHC pincer complexes of Rh and Ir.

The scope of CCC-NHC pincer complex synthetic methodology by metalation/transmetalation has been extended to Ir. Structural characterization revealed that it is isomorphous with the Rh complex. Both Rh and Ir complexes are efficient catalysts for the hydroamination/cyclization of secondary amines in the presence of air and/or water.