Biomedical subjects
Publications and source records attributed to A Hazell.
A mixed-valence dimanganese complex with two water ligands bound to the Mn(II) ion and two methoxide ligands bound to the Mn(III) ion in a H-bonded arrangement has been structurally characterised and models possible resting state water/hydroxide coordination in purple acid phosphatases.
The title compound, C9H9NS3, crystallizes with two molecules in the asymmetric unit. In both molecules, the dithiane-2-thione rings adopt a symmetric half-boat conformation with the C atom opposite the C--S(thione) bond out of the plane. The pyridine ring is in an equatorial position and is twisted out of the plane of the half-boat by 82.7 (2) and 84.5 (2) degrees in the two molecules, so that the N atom is trans to the axial C--H bond in both cases.
The use of the additive methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline has resulted in increased attention to the potential toxic effects of manganese (Mn). Hypothetically, people with chronic liver disease may be more sensitive to the adverse neurotoxic effects of Mn. In this work, bioaccumulation of Mn, as well as histopathology and neurobehavioral damage, in end-to-side portacaval anastomosis (PCA) rats exposed to Mn phosphate via inhalation was investigated. During the week before the PCA operation, 4 wk after the PCA operation, and at the end of exposure, the rats were subjected to a locomotor evaluation (day-night activities) using a computerized autotrack system. Then a group of 6 PCA rats (EXP) was exposed to 3050 microg m(-3) (Mn phosphate) for 8 h/day, 5 days/wk for 4 consecutive weeks and compared to a control group (CON), 7 PCA rats exposed to 0.03 microg m(-3). After exposure, the rats were euthanized and Mn content in tissues and organs was determined by neutron activation analysis. The manganese concentrations in blood (0.05 microg/g vs. 0.02 microg/g), lung (1.32 microg/g vs. 0.24 microg/g), cerebellum (0.85 microg/g vs. 0.64 microg/g), frontal cortex (0.87 microg/g vs. 0.61 microg/g), and globus pallidus (3.56 microg/g vs. 1.33 microg/g) were significantly higher in the exposed group compared to the control group (p <.05). No difference was observed in liver, kidney, testes, and caudate putamen between the two groups. Neuronal cell loss was assessed by neuronal cell counts. The loss of cells in globus pallidus and caudate putamen as well as in frontal cortex was significantly higher (p <.05) for the EXP group. Assessment of the locomotor activities did not reveal any significant difference. This study constitutes a first step toward our understanding of the potential adverse effects of Mn in sensitive populations.
N-(Phosphonomethyl)glycine, glyphosate, reacts with bis(tributyltin) oxide to form a ligand--tin (1:3) complex in which all five O atoms are coordinated to tin. The complex, [Sn(3)(C(4)H(9))(9)(C(3)H(5)NO(5)P)], is polymeric, with the glyphosate and two tributyltin groups forming a two-dimensional network and with the third Sn atom alternately above and below the plane of the net. The Sn atoms in the network have a trigonal-bipyramidal coordination, with O atoms in the axial positions and C atoms in the equatorial positions; the pendant tributyltin group is tetrahedrally coordinated to one O atom and to three butyl groups. Sn--O distances vary from 2.030 (3) to 2.408 (3) A. The Sn--O distances for O atoms trans to carboxylate groups are shorter than those trans to phosphonate groups and d(Sn--O) decreases with increasing d(C/P--O) (Delta(Sn--O) approximately -4.6 Delta(C/P--O)). The amino N atom in the ligand is neither protonated nor involved in coordination to the Sn atoms.
The title compound, aqua[bis(salicylidene)ethylenediaminato-O,N,N',O']oxovanadium(V) nitrate, [VO(C(16)H(14)N(2)O(2))(H(2)O)]NO(3), crystallizes as two polymorphs in the triclinic and monoclinic crystal systems. In both, the V atom has a distorted octahedral coordination geometry with a long V--O(water) bond trans to V==O. The coordinated water molecules are hydrogen bonded to the nitrate ions so that pairs of cations are linked to give neutral centrosymmetric dimers. The V==O and V--O(water) distances are 1.598 (2) and 2.257 (2) A, respectively, in the triclinic form, and 1.588 (3) and 2.230 (3) A, respectively, in the monoclinic form. In the triclinic form, the dimers pack so that the salen [bis(salicylidene)ethylenediaminate] ligands are parallel to each other, whereas in the monoclinic form, which is the denser, there is a herring-bone arrangement.
In the aqueous chemistry of molybdenum(IV) and tungsten(IV), trinuclear, incomplete cubane-like, oxo and sulfido clusters of the type [M3E4]4+ (M = Mo, W; E = O, S) play a central role. We here describe how formato complexes of all these cluster cores can be prepared in high yields by crystallization from methanol-water or ethanol-water mixtures. Since potassium and ammonium formate are very soluble in these alcohol-water mixtures, high formate concentrations could be accomplished in the solutions from which the corresponding salts of cluster formato complexes crystallized. The [Mo3O4]4+ compounds could be synthesized without requiring the use of noncomplexing acids in the process. Some [M3E4]4+ compounds were characterized by single-crystal structure determinations. [NH4]3.20[K]0.80[H3O][Mo3O4(HCO2)8][HCO2].H2O was triclinic, space group P1 (No. 2) with a = 11.011(2) A, b = 13.310(2) A, c = 9.993(1) A, alpha = 106.817(7) degrees, beta = 91.651(9) degrees, gamma = 88.340(9) degrees, and two formula units per cell. [K]6[W3S4(HCO2)9][HCO2].2.27H2O.0.73CH3OH was monoclinic, space group C2/m (No. 12) with a = 19.605(6) A, b = 14.458(7) A, c = 13.627(5) A, beta = 118.94(2) degrees, and four formula units per cell. Generally, the nine coordination sites of [M3E4]4+ were occupied either by a mixture of monodentate and mu 2-bridging formato ligands or by monodentate formato ligands only. By dissolution in noncomplexing strong acid, all the formato complexes immediately hydrolyzed to form [M3E4(H2O)9]4+ aqua complexes. This allows, for example, high concentrations of [Mo3S4(H2O)9]4+ in CF3SO3H to be obtained and these solutions to be used for the synthesis of bimetallic clusters containing the cubane-like motif Mo3M'S4.
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