Nickel Complexes of C-Substituted Cyclams and Their Activity for CO and H Reduction.

Several nickel(II) complexes of cyclams bearing aryl groups on the carbon backbone were prepared and evaluated for their propensity to catalyze the electrochemical reduction of CO to CO and/or H to H, representing the first catalytic analysis to be performed on an aryl-cyclam metal complex. Cyclic voltammetry (CV) revealed the attenuation of catalytic activity when the aryl group bears the strong electron-withdrawing trifluoromethyl substituent, whereas the phenyl, -tolyl, and aryl-free derivatives displayed a range of catalytic activities. The gaseous-product distribution for the active complexes was determined by means of controlled-potential electrolysis (CPE) and revealed that the phenyl derivative is the most active as well as the most selective for CO reduction over proton reduction.

Cr(III)-HMC (HMC = 5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane) Alkynyl Complexes: Preparation and Emission Properties.

Presented here is the chemistry of Cr(III) alkynyl complexes based on the rac-HMC and meso-HMC ligands (HMC = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Thus far, two pairs of cis/trans-[Cr(rac/meso-HMC)(C2R)2]Cl (R = Ph, C2H/C2SiMe3) complexes have been synthesized from reactions between cis/trans-[Cr(rac/meso-HMC)Cl2]Cl and LiC2R. These complexes were characterized using single crystal X-ray diffraction, UV-vis spectroscopy, FT-IR spectroscopy, and fluorimetry.

Turning a New Leaf on Metal-TMC Chemistry: Ni(II)(TMC) Acetylides.

Novel [Ni(TMC)C≡CY](+)-type compounds 1-4 [TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane; Y = SiMe3 (1), Si(i)Pr3 (2), Ph (3), and C2H (4)] have been synthesized and characterized. Single-crystal X-ray diffraction studies revealed that these compounds adopt a distorted square-pyramidal geometry, with the acetylide ligand occupying the apical position and a RSRS isomer for the TMC ligand. The room temperature magnetic properties of 1-4 are consistent with an S = 1 ground state, as corroborated by CASSCF and density functional theory calculations, which indicate that the singly occupied molecular orbitals are d(z(2)) and d(x(2)-y(2)).

Diruthenium-polyyn-diyl-diruthenium wires: electronic coupling in the long distance regime.

Reported herein is a series of Ru2(Xap)4 capped polyyn-diyl compounds, where Xap is either 2-anilinopyridinate (ap) or its aniline substituted derivatives. Symmetric [Ru2(Xap)4](μ-C4k)[Ru2(Xap)4] (compounds 4ka (X = 3-isobutoxy) and 4kc (X = 3,5-dimethoxy) with k = 2, 3, 4, and 5) was obtained from the Glaser coupling reaction of Ru2(Xap)4(C2kH). Unsymmetric [Ru2(Xap)4](μ-C(4k+2))[Ru2(ap)4] (compounds 4k+2b with k = 2, 3, and 4) were prepared from the Glaser coupling reaction between Ru2(Xap)4(C(2k+2)H) and Ru2(ap)4(C2kH).