Magnesium atomic structure

Crystals of the intermetallic compound magnesium stannide, MgjSn, have been prepared and investigated by means of Laue and spectral photographs with the aid of the theory of space-groups. The intermetallic compound has been found to have the calcium fluoride structure, with dwo = 6.78 0.02 A. U. The closest approach of tin and magnesium atoms is 2.94 0.01 A. U. 

The nature of the structure found for this phase, with strong indication that there are thirty-two magnesium atoms per lattice point, suggests that the quaternary phase should be assigned the general formula Mg32(Al, Zn, Cu)49. 

Figure 113 Schematic crystal structure of one layer of talc. Such layers are stacked to make the complete structure. The large and medium open circles represent oxygen atoms.The cross-hatched large circles represent hydroxyls (OH).The small open circles represent magnesium atoms (Mg) and the cross-hatched small circles represent silicon (Si) atoms. Figure is reproduced from Bragg, Claringbull and Taylor (1965).

Several possible explanations suggest themselves. One possibility is that specific interactions between the ether oxygen of THF and the magnesium atom of the MgP moiety would alter the electronic structure of the dimer such as to increase that is, favorable 0—Mg interactions... 

At the same time the structures in the solid state of Mc2Mg and Et2Mg were determined by X-ray powder diffraction studies . Both compounds form polymeric chains as the result of the bridging of two methyl groups between two magnesium atoms, rendering the magnesium atoms almost perfectly tetrahedrally coordinated. 

The structure of the cationic part of 7 consists of a [Mg3C2] trigonal bipyramidal arrangement (Figure 8) with the magnesium atoms in the equatorial plane and the carbon atoms at the apical positions. The two allyl groups are /r3-bonded (one above and one... 

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