Crystal structure analyses of reduced (CuI) poplar plastocyanin at six pH values.

Pterin-Dependent Amino Acid Hydroxylases.

Model systems for type I copper proteins: structures of copper coordination compounds with thioether and azole-containing ligands

Dinuclear iron- and manganese-oxo sites in biology

Mononuclear iron(II) α-keto carboxylate and carboxylate compounds of the sterically hindered tridentate face-capping ligand TpPh2 (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate) were prepared as models for the active sites of nonheme iron oxygenases. The structures of an aliphatic α-keto carboxylate complex, [FeII(TpPh2)(O2CC(O)CH3)], and the carboxylate complexes [FeII(TpPh2)(OBz)] and [FeII(TpPh2)(OAc)(3,5-Ph2pzH)] were determined by single-crystal X-ray diffraction, all of which have five-coordinate iron centers. Both the α-keto carboxylate and the carboxylate compounds react with dioxygen resulting in the hydroxylation of a single ortho phenyl position of the TpPh2 ligand. The oxygenation products were characterized spectroscopically, and the structure of the octahedral iron(III) phenolate product [FeIII(TpPh2*)(OAc)(3,5-Ph2pzH)] was established by X-ray diffraction. The reaction of the α-keto carboxylate model compounds with oxygen to produce the phenolate product occurs with concomitant oxidativ...

Oxygen Activation by Nonheme Iron(II) Complexes: α-Keto Carboxylate versus Carboxylate

Small molecule analogs for the specific iron-binding site of lactoferrin: a single-crystal x-ray structure of bis(methanol)bis[2-(5-methylpyrazol-3-yl)phenolato]iron(III) nitrate-methanol and spectroscopic studies on iron(III) phenolate complexes

Crystals of (Me4N)2Ga2Cl6 are cubic, a= 13·097 A, space group Pa3, Z= 4. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by least-squares techniques to R 0·076 for 384 observed reflections. The analysis confirms the existence of a Ga2Cl62– ion, of symmetry D3d, with a Ga–Ga bond of length 2·39 A.

Crystal structure of tetramethylammonium hexachlorodigallate(II)

Crystals of [(CuClL2)22(CuClL2)][L2= bis(diphenylphosphinothioyl)methane] are triclinic, space group P, with a= 11.345(2), b= 16.569(3), c= 14.512(2)A, α= 81.05(1), β= 78.76(1), γ= 109.09(1)°, and Z= 2. The structure was solved by direct methods and refined to R= 0.098 full-matrix least squares for 4 267 diffractometer data. It shows [(CuClL2)22(CuClL2)] to be structurally mixed complex with three-co-ordinate monomers tetrahedral sulphur-bridged dimers, co-existing in the same crystal. The formation of [(CuClL2)22(CuClL2)] from [CuClL2]. Me2CO (a three-co-ordinate monomer) has been followed by differential scanning calorimetry. The interaction of L2, PMe2PhS, and P(NEt2)3S with copper(II) ions has allowed the identification of Ph2P(S) CH2P(O)Ph2, PMe2PhO, and [(Et2N)3 P–S–S–P(NEt2)3]2+ respectively, as oxidised ligand species.

Sulphur-ligand–metal complexes. Part 8. Bis(diphenylphosphinothioyl)methane complexes of copper(I)

The ligand 2-(3,3-dimethyl-2-thiabutyl)pyridine (L) and its protonated cation, 2-(3,3-dimethyl-2-thiabutyl)-pyridinium ion (LH+), have been used to prepare the copper(I) complexes [CuLnBr](n= 1 or 2) and [Cu(LH)X2](X = Cl or Br). Electronic and i.r. spectroscopic data for these complexes are presented, and the chemical relationships between them discussed. The crystal and molecular structures of [CuL2Br] and [{Cu(LH)Br2}2] have been determined by single-crystal X-ray diffraction techniques, from diffractometer data. Crystals of [CuL2Br] are monoclinic, space group P21/n, with a= 16.927(3), b= 8.867(1), c= 15.371(2)A, β= 100.61(1)°, and Z= 4. Crystals of [{Cu(LH)Br2}2] are also monoclinic, space group P21/n, with a= 15.700(3), b= 9.038(3), c= 9.926(2)A, β= 98.66(1)°, and Z= 2. After full-matrix least-squares refinement final R values are 0.066 (for 2 032 observed reflections) and 0.047 (for 1 538 observed reflections) respectively. The complex [CuL2Br] is monomeric, the distorted tetrahedral geometry round the copper atom being completed by a bromide ion [Cu–Br 2.424(2)A], the pyridyl nitrogen and thioether sulphur of a bidentate ligand L [Cu–N 2.109(9), Cu–S 2.357(3)A], and the thioether sulphur of a unidentate ligand L [Cu–S 2.310(3)A]. The complex [{Cu(LH)Br2}2] exists as a centrosymmetric dimer with the distorted tetrahedral copper(I) centres dibromo-bridged [Cu–Br 2.597(1)A]. The two remaining co-ordination positions round each copper are occupied by a terminal bromide ion [Cu–Br 2.363(1)A] and the thioether sulphur [Cu–S 2.276(2)A] of an LH+ cation.

Copper co-ordination to thioether ligands. Chemical, spectroscopic, and crystallographic studies on copper(I) complexes of 2-(3,3-dimethyl-2-thiabutyl)pyridine and the 2-(3,3-dimethyl-2-thiabutyl)pyridinium cation

The interaction of 1,1′-biphenyl-2,2′-diol (H2L) with iron(III) perchlorate in the presence of piperidine yields the title complex [C5H12N]2[(FeL2)2]·2EtOH, the crystal and molecular structure of which has been determined by single-crystal X-ray diffraction techniques. Crystals of the complex are triclinic, space group P, with a= 14.058(2), b= 9.976(1), c= 12.517(1)A, α= 73.41 (1), β= 65.29(1), γ= 61.48(1)°, and Z= 1. After full-matrix least-squares refinement the final R value is 0.052 for 3 473 observed reflections. The complex contains [(FeL2)2]2– dimers with seven-membered chelate rings, as well as piperidinium ions and ethanol molecules of crystallization. Each FeIII is bonded to five oxygen atoms from L2– ligands to give a distorted trigonal-bipyramidal co-ordination. The iron atoms are bridged by phenolate oxygens. The ethanol molecules, piperidinium ions, and L2– ligands are linked by hydrogen bonds. Spectroscopic and magnetic data are in keeping with the dimeric [(FeL2)2]2– structure, with weak antiferromagnetic coupling via the bridging oxygen atoms. Spectroscopic evidence indicates that the dimers are dissociated by nitrogen-donor solvents.

The reaction of 1,1′-biphenyl-2,2′-dial with iron(III) and the crystal structure of piperidinium bis[µ-(1,1′-biphenyl-2,2′-diolato-O,µ-O′)(1,1′-biphenyl-2,2′-diolato-O,O′)ferrate(III)]–ethanol(½)

Kevin L. Brown

Papers

Small molecule analogs for the specific iron-binding site of lactoferrin: a single-crystal x-ray structure of bis(methanol)bis[2-(5-methylpyrazol-3-yl)phenolato]iron(III) nitrate-methanol and spectroscopic studies on iron(III) phenolate complexes

Crystal structure of tetramethylammonium hexachlorodigallate(II)

Sulphur-ligand–metal complexes. Part 8. Bis(diphenylphosphinothioyl)methane complexes of copper(I)

Copper co-ordination to thioether ligands. Chemical, spectroscopic, and crystallographic studies on copper(I) complexes of 2-(3,3-dimethyl-2-thiabutyl)pyridine and the 2-(3,3-dimethyl-2-thiabutyl)pyridinium cation

The reaction of 1,1′-biphenyl-2,2′-dial with iron(III) and the crystal structure of piperidinium bis[µ-(1,1′-biphenyl-2,2′-diolato-O,µ-O′)(1,1′-biphenyl-2,2′-diolato-O,O′)ferrate(III)]–ethanol(½)