Davis 1 Manganese

An X-ray diffraction study of MnRe(CO)io has shown the solid to exhibit a reversible structural change at 343 K with a transition enthalpy of 3.23 kcal moP The concept of the semi-bridging carbonyl group has been extended to the Group VIIB carbonyls. MO calculations on M2(CO)iq (M = Mn or Re) suggest that the equatorial carbonyl groups of the former, but not the latter, can be considered as semi-bridging.  

Alkali-metal reduction of Mn2(CO)io in hexamethylphosphoramide yields the new anion Mn(CO)4 [v(CO), 1805, 1670 cm ], which reacts with PhjECl to give 

Electrochemical oxidation of (7t-Cp)Mn(CO)3 and Mn(CO)5Br at the platinum electrode in CF3COOH yields the corresponding 17-electron cations however, Mn2(CO)io gives Mn(C0)s(CF3C02)  

Structural studies on cis- and trans-[Mn(CO)2 P(OMe)2Ph 4]PFg were performed in order to see if any variations in Mn—C bond lengths are apparent and if the more inert nature of the cations, compared with the neutral compounds, is paralleled by a reduction in Mn—C lengths. It was found that the Mn—P distances were almost 

Reactions of cis-Mn(CO)4LBr (L = PPh3, AsPh3, or SbPhj) with C 0 suggest that while all four carbonyls exchange eventually, there is an initial stereochemical preference for axial substitution. A related study of exchange with cis- 

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Some aspects of the chemistry of manganese(III) in aqueous solution. G. Davies, Coord. Chem. Rev., 1969,4,199-224(101). 

Davies, S. and Morgan, J. J. (1989). Manganese (II) oxidation kinetics on metal oxide surfaces, /. Colloid... 

Carl Wilhelm Scheele (1742-1786) discovered chlorine in the reaction of hydrochloric acid with manganese dioxide (pyrolusite or brownstone ore). Recognized as an element by Sir Humphry Davy (1778-1829). 

The processes described and their kinetics is of importance in the accumulation of trace metals by calcite in sediments and lakes (Delaney and Boyle, 1987) but also of relevance in the transport and retention of trace metals in calcareous aquifers. Fuller and Davis (1987) investigated the sorption by calcareous aquifer sand they found that after 24 hours the rate of Cd2+ sorption was constant and controlled by the rate of surface precipitation. Clean grains of primary minerals, e.g., quartz and alumino silicates, sorbed less Cd2+ than grains which had surface patches of secondary minerals, e.g., carbonates, iron and manganese oxides. Fig. 6.11 gives data (time sequence) on electron spin resonance spectra of Mn2+ on FeC03(s). 

Adsorption may influence precipitation by means other than the processes mentioned above. Davies (Chapter 23) discusses the role of the surface as a catalyst for oxidation of adsorbed Mnz+. Redox reactions may contribute substantially to the formation of manganese oxide coatings on mineral surfaces in soils and sediments. 

When Sir Humphry Davy isolated a little magnesium metal in the famous experiments already described, he called it magnium because, as he said, the word magnesium is easily confused with manganese. Nevertheless, the name magnesium has persisted, and the metal is no longer known by the one which Davy gave it. 

By the action of marine acid on the black oxide of manganese, Scheele obtained chlorine gas and described its principal characteristic properties. He called it dephlo-gisticated marine acid. The name was reasonable from his point of view, since inflammable air (hydrogen) was conceived to be chiefly phlogiston and the above action deprived marine acid of its hydrogen. Chlorine was not conceived to be elementary in its nature even by Lavoisier Sir Humphry Davy, in 1810, was the discoverer of its elementary nature, and he it was who suggested the name chlorine. ... 

Hohmeier, H.E., Thigpen, A., Tran, V. V., Davis, R. andNewgard, C.B. (1998) Stable expression of manganese superoxide dismutase (MnSOD) in insulinoma cells prevents IL-1 beta-induced cytotoxicity and reduces nitric oxide production. J. Clin. Invest., 101, 1811-1820. 

In 1808 Davy first called magnesium magnium, since magnesium had been used for another metal, which we now call manganese in 1812, Davy withdrew magnium and used magnesium, in spite of its former use. 

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