Redetermination of bis(2-amino-3-hydroxy-1-phenylpropanolato-κ 2 N , O 1 )(ethylenediamine-κ 2 N , N ′)cobalt(III) iodide monohydrate

New data for the title complex, [Co(C9,H12NO 2)2(C2H8N2)]I-H 2O, allow the modelling of previously unresolved disorder [Wardeska et al. (1979). Inorg. Chem. 18, 1641-1648] in the ethylenediamine ligand coordinated to the octahedral cation

Crystal structure of the ferritin from the hyperthermophilic archaeal anaerobe Pyrococcus furiosus

The crystal structure of the ferritin from the archaeon, hyperthermophile and anaerobe Pyrococcus furiosus (PfFtn) is presented. While many ferritin structures from bacteria to mammals have been reported, until now only one was available from archaea, the ferritin from Archaeoglobus fulgidus (AfFtn). The PfFtn 24-mer exhibits the 432 point-group symmetry that is characteristic of most ferritins, which suggests that the 23 symmetry found in the previously reported AfFtn is not a common feature of archaeal ferritins. Consequently, the four large pores that were found in AfFtn are not present in PfFtn. The structure has been solved by molecular replacement and refined at 2.75-Å resolution to R = 0.195 and Rfree = 0.247. The ferroxidase center of the aerobically crystallized ferritin contains one iron at site A and shows sites B and C only upon iron or zinc soaking. Electron paramagnetic resonance studies suggest this iron depletion of the native ferroxidase center to be a result of a complexation of iron by the crystallization salt. The extreme thermostability of PfFtn is compared with that of eight structurally similar ferritins and is proposed to originate mostly from the observed high number of intrasubunit hydrogen bonds. A preservation of the monomer fold, rather than the 24-mer assembly, appears to be the most important factor that protects the ferritin from inactivation by heat

A Solvent Directed Synthesis of Mixed-Valence Cobalt(III,II) Compounds

The cobalt(III) complexes, [Co(acac)2(amine)2]X, have been reported for a variety of amines and counter ions, X. While synthesizing a series of thiocyanato complexes, two complexes, [Co(acac)2(pyr)2]SCN and (Co(acac)2(4-Mepyr)2]SCN, were observed to undergo a reaction (Equation 1) forming green products in chloroform and acetic acid solution. These products have been characterized as [Co(acac)2(amine)2]2Co(NCS)4, which contain paramagnetic Co(II) and diamagnetic Co(m) moieties

Characterization of a Dimeric Copper(II) Complex of a Dissymmetric Schiff Base and Its Ligand Adducts

The synthesis and characterization of a binuclear copper(II) complex of a Schiff base derived from salicylaldehyde and (1S,25)-(+)D-1-phenyl-2-amino-1,3-propanediol are described. A distorted square-planar configuration about the copper centers is proposed on the basis of its spectral properties and its reduced magnetic moment in solution. The complex reacts in solution with a series of ligands to form bis(ligand) adducts in which the dimeric unit remains intact. The bis(imidazole) adduct exhibits catalase activity, and in the presence of hydrogen peroxide a band near 440 nm is observed that is most probably a 022−–Cu(II) charge-transfer transition

Cobalt(III) Complexes of Amino Alcohols. Structural Consequences of Protonation

The crystal structure of the diprotonated form of cis-α-Δ-(-)589-[Co|(+)-PAHP)2en-δδγ]+ (PAHP = monoanion of 1-phenyl-2-amino-l,3-dihydroxypropane), Co(C9H12NO2H)2 (C2N2H8)C13-2H2O, has been determined by single-crystal X-ray diffraction methods. The crystals are orthorhombic, space group P212121 with a = 14.113 (2) Å, b = 18.782 (5) Å, c = 10.175 (2) Å, and Z = 4. Full-matrix least-squares refinement gave an R index of 0.044 for 2060 observed reflections with intensities greater than 3cr. The absolute configuration was determined by refinement of both enantiomorphs. The protonation sites were inferred to be the alcohol oxygens bonded to cobalt from the very short Cl-O interatomic distances. As a consequence, the Co-O and C-O bonds are lengthened. The effect of protonation upon other structural features is described