Crystallographic structure magnesium

Griffin et al. showed the Mg NMR parameters have been determined for two polymorphs of enstatite (MgSi03), an important magnesium silicate phase present as a major component of the Earth s upper mantle. The crystal structures of both polymorphs contain two crystallographically distinct magnesium sites however, only a single resonance is observed in... 

Figure 7 The functionalization of MOFs and their interactions with COj. (a) The crystallographic structure of Ni-MOF-74 in the presence of COj, where the CO2 coordinates to unsaturated nickel centers in an end-on manner. (b) The introduction of Lewis base (mmen) into an analogous Mg-MOF with larger cavities, where the mmen coordinates to the unsaturated magnesium centers. (Figure 7b Reprinted with permission from Ref 5. Copyright (2012) American Chemical Society.)...

Magnesium chloride has a crystal structure very similar to violet titanium trichloride. This dictates the possibility of an epitaxial coordination of TiCU units (or TiCl3 units, after reduction) on the lateral coordinatively unsatured faces of MgCl2 crystals, giving rise to relieves crystallographically coherent with the matrix.150... 

Only the NaCl region has been measured for magnesium and calcium orthovanadates (57) thus no data are available for either of the bending vibrations. Previously the IR spectrum of Ca3(V04)2 had been discussed with incorrect crystallographic data. An X-ray structural analysis has only recently been reported 54) which shows that in the lattice crystallographicaUy non-equivalent VO4 groups are present. Also in the case of Mg3(V04)2 it was not previously possible to differentiate between two possible site symmetries, C2 or Cj 51). A recently reported crystallographic study shows that the VO4 ions sit on C, sites (55). 

The magnesium atom of compound 62a lies on a crystallographic inversion center, and consequently the substituents are in awft-configuration. The structure of 62b shows an eclipsed conformation and leads to steric repulsion between the dicyclopropy-Imethyl groups (Figure 36). As a consequence a slight deviation from linear structure is observed. 

The magnesium aluminate spinels that we have tested are MgAl204 and Mg Al Og. The latter is a solid solution (2,3) of pure spinel (MgAl204) and MgO. The spinel structure (4) is. based on a cubic close packed array of oxide ions. Typically, the crystallographic unit cell contains 32 oxygen atoms one eighth of the tetrahedral holes are occupied by the divalent metal ions (Mg2+), and one half of the octahedral holes are occupied by the trivalent metal ions (Al3+). 

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