William H. Ilsley

Crystal structure of zinc citrate

Abstract The crystal structure of zinc citrate [Zn(II) (C 6 H 5 O 7 ) 2 ·4NH 4 + ] shows isolated zinc ions octahedrally coordinated to two equivalent citrates via a central hydroxyl, central carboxyl, and one terminal carboxyl from each citrate. The clusters are linked through hydrogen bonds to ammonium ions in the lattice. The structure is distinctly different from that of other divalent cation triply ionized citrate complexes, which are polymeric. Crystal data : space group P 2 1 / C , a = 8.784(3) A, b = 13.499(4) A, c = 9.083(3) A, β = 113.4°(1), V = 988(1) A 3 . Citrate has been identified as the low molecular weight ligand that complexes zinc in human milk; this may be of interest in relation to intestinal zinc absorption.

The reactivity of ruthenium textroxide towards aromatic and etheric functionalities in simple organic compounds

The reactivity of ruthenium tetroxide towards coal-like organic functionalities was investigated by oxidizing model substrates containing aromatic and etheric functionalities with RuO2.3H2O in the presence of variable amounts of NaIO4 as the cooxidant. Molar cooxidant/substrate ratios (cs) of between 2 and 8 were employed. Most substrates gave low product yields at low cs ratios, but product distributions obtained at the various cs ratios indicate that most functionalities are initially attacked at more than one site, forming products which can themselves be further oxidized. Phenyl groups are rapidly oxidized to CO2 when the ring is activated by electron donating substituents, but slowly, or not at all when an electron withdrawing group is present. The alkyl benzyl ether group is oxidized rapidly and exclusively to the alkyl benzoate derivative with two equivalents of cooxidant, and the product ester is inert towards further oxidation at a higher cs ratio. Phenylpentadecane is oxidized at the aromatic ring and at the benzylic methylene, even at low cs ratios, to form hexadecanoic acid, pentadecanophenone, and pentadecanoic acid, Higher cs ratios produce significant amounts of shorter chain acids with no increase in the yield of phenone. Dihydroanthracene is oxidized rapidly to anthracene, but small amounts of anthrone and anthraquinone are also formed. At higher cs ratios anthracene is slowly oxidized to the latter products.

Preparation and characterization of bis(2-thiopyrimidinato)bis(pyridine)dioxodi(μ-oxo)dimolybdenum(V)

Abstract The reaction of Mo2(O2CCH3)4 with 2-mercaptopyrimidine gave a green solid which was transformed by dissolving in pyridine in air to a red-orange crystalline product which has been shown by X-ray crystallography to be [MoO(NC5H5)(SN2C4H3)] 2(μ-O)2. The molecule has the familiar oxo-bridged dinuclear structure with the MoO bonds cisoid and distorted octahedra completed about each metal atom by a pyridine nitrogen atom, a pyrimidine nitrogen atom and the pyrimidine sulfur atom. No crystallographic symmetry is imposed but the molecule closely approximates C2 symmetry. The MoMo distance is 2.576(1)A. The crystallographic parameters are: Space group, P 1 ; a = 12.063(7)A; b = 12.149(5)A; c = 10.362(5)A; α = 98.51(3)°; β = 104.84(4)°; γ = 102.91(4)°; V = 1396(1)A3; Z = 2. Using 3389 data with Fo2 >; 3σ(Fo2) and 313 variables, the structure was refined bu full-matrix least squares to final discrepancy indices of R1 = 0.044 and R2 = 0.073.

Chelate rings in a quadruply bonded dimetal compound: Preparation and structure of diacetatodi(4-phenylimino-2-pentanonato)dimolybdenum

Abstract Lithium (4-phenylimino)-2-pentanonide reacts with Mo 2 (O 2 CCH 3 ) 4 to replace two acetate ligands and afford red, crystallineMo 2 (O 2 CCH 3 ) 2 [PhNC(CH 3 )CHC(CH 3 )O] 2 . The crystal and molecular structures have been determined by X-raycrystallography. The crystals belong to space group P 1 with a = 11.723(3) A , b = 10.402(2) A , c = 12.624(2) A ; α = 112.88(1)°, β = 95.04(1)°, γ = 107.01(1)°, and Z = 2. The structure has a cisoid arrangement of the bridging acetate ligands and one chelate ring on each metal atom. The unsymmetrical chelate ligands are so arranged that the virtual symmetry is C 2 . The MoMo distance is 2.131(1) A .