Magnesium, tris salts complexes

Tris(indenyl)lanthanide complexes of all rare earth metals can be prepared analogously from the lanthanide trichlorides with alkali or magnesium indenyl salts. All five-membered rings are -bonded to the metal. They form base adducts with... 

Chromates are usually yellow or red in colour, and, except those of ammonium, the alkali metals, calcium, strontium, and magnesium, are practically insoluble in w ater. They are obtained by oxidation of chromites, by fusion of chromium sesquioxide with the appropriate base in presence of air or of an oxidising agent by oxidation of chromium salts in solution or by double decomposition. Normal, di-, and tri-clrromates, etc., are derived from one and the same acid oxide KaCrOj behaves like an alkali torvards CrOg, since it is quantitatively converted into dichromate. A large number of complex double chromates are known. 

In analogy to aromatic C-H bonds, alkenyl C-H bonds can also be activated by iron(III) salts in coupling reactions with magnesium or zinc organyls (Scheme 4-250). The reaction requires a pyridine or an imine moiety in proximity to the double bond that supports the C-H bond activation step by chelation of the intermediate iron complex. Tris(acetylacetonato)iron is employed in catalytic amounts and l-bromo-2-chIoroethane or l,2-dichloro-2-methylpropane functions as oxidant. In addition, in most cases a diamine base is added. The reaction results in the stereospecific substitution of the olefinic C-H bond syn to the coordinating group. ... 

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