Magnesium compounds oxygen complexes

Chrome ore is a basic rock containing chromium, iron, aluminium, magnesium and oxygen combined together as a complex crystalline compound called a spinel. In addition, the mineral serpentine, Mg3Si205(0H)4, is present as an impurity, sometimes called the ganguc. ... 

Mono-n-cyclopentadienylmagnesium compounds have so far only been isolated in the form of adducts with oxygen or nitrogen bases. The bis-(tetrahydrofuran) complexes of cyclopentadienyl(phenyl)- and -(methyl)-magnesium have been synthesized by Whitesides and co-workers (96) according to Eq. (4). 

Alkali-earth metals (calcium, barium, and magnesium) complex with polysaccharides extensively (Reisenhofer et al., 1984). Calcium has a smaller atomic and ionic radius than does sodium and, because it has two valence electrons, it is endowed with greater polarizing and bonding ability than Na+. Ca and Ca2+ easily form insoluble complexes with oxygenated compounds. Polysaccharide salts of alkali-earth metals are generally insoluble. 

The reactivity of organometals increases in the order Li < Na < K alkali metal organometals are more efficient than magnesium and aluminium compounds and the reaction of aryllithium organometals with ketones is more rapid than that of alkyllithium compounds [202], Wittig and Bub [204, 205] postulated the formation of transition complexes with simultaneous nucleophilic attack on the carbonyl and electrophilic attack on the oxygen by the metal. 

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