Thermodynamic targeting of electrocatalytic CO reduction: advantages, limitations, and insights for catalyst design.

Herein is reported the electrocatalytic reduction of CO with the complex [Ni(bis-NHC)(dmpe)] (1) (bis-NHC = 1,l':3,3'-bis(1,3-propanediyl)dibenzimidazolin-2,2'-diylidene; dmpe = 1,2-bis(dimethylphosphino)ethane). The hydricity of 1 was previously benchmarked to be , equating to a driving force of a minimum of ∼3.4 kcal mol for hydride transfer to CO.

Chelated [Zn(cyclam)] Lewis acid improves the reactivity of the electrochemical reduction of CO by Mn catalysts with bulky bipyridine ligands.

This communication reports the use of a soluble Lewis acid complex, [Zn(cyclam)] (cyclam = 1,4,8,11-tetraazacyclotetradecane) as a co-catalyst coupled with Mn(Mesbpy)(CO)Br (Mesbpy = 6,6'-dimesityl-2,2'-bipyridine) for the electrochemical reduction of CO to CO. Utilization of the soluble chelated Lewis acid avoids the use of sacrificial additives and prevents the formation of insoluble products such as MgCO or ZnCO that change the thermodynamics of CO reduction. The use of soluble Lewis acids greatly improves catalysis compared to previously reported systems that used sacrificial anodes.

Incorporation of Pendant Bases into Rh(diphosphine)2 Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO2 Hydrogenation Activity of [Rh(P2N2)2](+) Complexes.

A series of five [Rh(P2N2)2](+) complexes (P2N2 = 1,5-diaza-3,7-diphosphacyclooctane) have been synthesized and characterized: [Rh(P(Ph)2N(Ph)2)2](+) (1), [Rh(P(Ph)2N(Bn)2)2](+) (2), [Rh(P(Ph)2N(PhOMe)2)2](+) (3), [Rh(P(Cy)2N(Ph)2)2](+) (4), and [Rh(P(Cy)2N(PhOMe)2)2](+) (5). Complexes 1-5 have been structurally characterized as square planar rhodium bis-diphosphine complexes with slight tetrahedral distortions. The corresponding hydride complexes 6-10 have also been synthesized and characterized, and X-ray diffraction studies of HRh(P(Ph)2N(Bn)2)2 (7), HRh(P(Ph)2N(PhOMe)2)2 (8) and HRh(P(Cy)2N(Ph)2)2 (9) show that the hydrides have distorted trigonal bipyramidal geometries.

Synthesis and structural studies of nickel(0) Tetracarbene complexes with the introduction of a new four-coordinate geometric index, τδ.

The synthesis and characterization of two homoleptic chelating nickel(0) tetracarbene complexes are reported. These are the first group 10 M(0) (M = Ni, Pd, Pt) tetracarbene complexes. These species have geometries intermediate between C2v sawhorse and tetrahedral and show high UV-vis absorption in the 350-600 nm range, with extinction coefficients (ϵ) between 5600 and 9400 M(-1) cm(-1).