Search

To improve understanding of copper at the active site of Type 1 copper proteins, CuI and CuII complexes of 1,8-dithia-4,11-diazacyclotetradecane, shown in FIGREFFig. 1/FIGREF, have been successfully isolated and structurally characterized by X-ray crystallography. In these compounds, both CuI and CuII are centered in the plane of the macrocycle containing two sulphur and two nitrogen heteroatoms comprising the distorted tetrahedral/square planar coordination geometry. The UV/VIS spectra, electrochemistry and EPR properties have been obtained for the CuII complex 2. Three absorption bands at 295 nm, 354 nm, and 545 nm are observed in aqueous solution at a pH of 5. These bands have been assigned to the N → CuII and S → CuII charge transfer bands and the d–d transitions respectively. The CuI/II redox midpoint potential of complex 2 in CH3CN is +403 mV versus NHE. [ABSTRACT FROM AUTHOR]

Irradiation of [Ru(bpy)2(bpSOp)](PF6)2 (where bpy is 2,2'-bipyridine and bpSOp is 1,3-bis(phenylsulfinyl)-propane) results in the formation of two new isomers, namely the S,O- and O,O-bonded species. The crystal structure of the bis-thioether and bis-sulfoxide complexes are reported. NMR spectroscopy of the bis-thioether complex in solution is consistent with the molecular structure determined by diffraction methods. Further, NMR spectroscopy of the bis-sulfoxide complex reveals two conformers in solution, one that is consistent with the solid state structure and a second conformer showing distortion in the aliphatic portion of the chelate ring. Time-resolved visible absorption spectroscopy reveals isomerization time constants of 91 ps in dichloroethane (DCE) and 229 ps in propylene carbonate (PC). Aggregate isomerization quantum yields of 0.57 and 0.42 have been determined in DCE and in PC, respectively. The kinetics of the thermal reversion from the O,O- to S,O-bonded isomer are strongly solvent dependent, occurring with rates of 2.41 × 10-3 and 4.39 × 10-5 s-1 in DCE, and 4.68 × 10-4 and 9.79 × 10-6 s-1 in PC. The two kinetic components are assigned to the two isomers identified in solution. [ABSTRACT FROM AUTHOR]

In this report we present a study of a series of Re(CO)3 pyridine–imine complexes with pendant phenol groups. We investigated the effects of the position of the phenol hydroxyl group (para, meta or ortho to the imine) on the steric and electronic characteristics of a series of Re(CO)3X(pyca-C6H4OH) compounds, where X = Cl, Br and pyca = pyridine-2-carbaldehyde imine. These compounds can be generated either via ligand synthesis followed by metal chelation (compound 4) or via a one-pot method (compounds 2, 3, 5 and 6). All six compounds show striking differences in pH-dependent UV-visible absorption based on the position of the phenol hydroxyl group. [ABSTRACT FROM AUTHOR]

Cobalt complexes of N-confused porphyrins and benziphthalocyanine, which both feature organometallic bonds at the macrocycle cores, catalyze the cyclopropanation of styrene with a higher trans-selectivity than the corresponding porphyrin and phthalocyanine complexes. [ABSTRACT FROM AUTHOR]