Non-heme iron and manganese species with terminal oxo ligands are proposed to be key intermediates in a variety of biological and synthetic systems; however, the stabilization of these types of complexes has proven difficult because of the tendency to form oxo-bridged complexes. Described herein are the design, isolation, and properties for a series of mononuclear Fe(III) and Mn(III) complexes ...

A chromatographic method was developed for simultaneous determination of Fe(III), Fe(II), Mn(II), and other transition metals. A high-performance polymer-coated silica-based cation exchange column was used for the separation of metals from hydrochloric acid-extracted environmental samples. After separation, the metals were mixed with PAR [4-(2-pyridylazo)resorcinol] and passed through a superco...

Minerals constitute a primary ecosystem control on organic C decomposition in soils, and therefore on greenhouse gas fluxes to the atmosphere. Secondary minerals, in particular, Fe and Al (oxyhydr)oxides-collectively referred to as "oxides" hereafter-are prominent protectors of organic C against microbial decomposition through sorption and complexation reactions. However, the impacts of Mn oxid...

The synthesis and characterization of the monomeric, two-coordinate transition-metal complexes (2,6-Mes(2)C(6)H(3))(2)M (Mes = mesityl, 2,4,6-Me(3)C(6)H(2), M = Mn, Fe, Co) are reported; (2,6-Mes(2)C(6)H(3))(2)Co is the first structurally authenticated two-coordinate, homoleptic cobalt(II) complex featuring sigma-bonded aryl ligands.

metalloporphirins; cu(tpp), mn(tpp)cl, co(tpp), fe(tpp)cl, zn(tpp) and mn(obp)cl catalyze region and chemoselective silylation of hydroxyl groups with hmds. fe(tpp)cl is the most effective catalyst and silylation occurs immediately in its presence at room temperature.

When a number of metal ions were tested as activators over a lOO-fold range of metal ion concentration (0.01 to 1.0 mM), aconitase was specifically activated by Fe(II). Manganese(I1) does not activate aconitase but binds to the enzyme, as shown indirectly by inhibition of the enzyme activation by Fe(I1) and directly by electron paramagnetic resonance. A titration of the enzyme with Mn(I1) may b...

At the Clarabelle mill, significant amounts of rock minerals float inadvertently during nickel and copper sulfide flotation, causing poor concentrate grades. It is known that the rock minerals that report to the concentrates are amphiboles and phyllosilicates. However, the latter are found only on concentrates obtained by processing highly altered ores. The amphiboles, which occur as both prima...

We explore Fe/Mn and Nb/Ta ratios of basalts as potential tracers for differentiating melts of recycled mafic crustal lithologies from peridotitic melts. Trace elements and Fe/Mn ratios of the Mesozoic and Cenozoic basalts from East China were analyzed by ICP-MS. Low Nb/Ta ratios (15.4 ± 0.3 (2r, n = 45)), high Nb and Ta contents (60.1 and 4.01 ppm) and high Fe/ Mn ratios (64.7 ± 1.5 (2r, n = 4...

The uptake of Mn(2+), a cofactor for several enzymes in Escherichia coli, is mediated by MntH, a proton-dependent metal transporter, which also recognizes Fe(2+) with lower affinity. MntH belongs to the NRAMP family of eukaryotic Fe(2+) and Mn(2+) transporters. In E. coli strains with chromosomal mntH-lacZ fusions, mntH was partially repressed by both Mn(2+) and Fe(2+). Inactivation of fur resu...