Magnesium interatomic distance

The magnesium complexes 53 (72) and 54 (73) are structurally very similar to 6 and 7. Methyl and phenyl groups bridge the two metal atoms. The lithium-magnesium interatomic distances in 53 and 54 (2.62 and 2.94 A, respectively) are less than the sum of the atomic radii for these metals (3.15 A), (74), indicating that some degree of metal-metal interaction may be present. 

The ratio Rnt /Ro- is 0.46, so that in magnesium oxide the mutual repulsion of the oxide ions is beginning to have influence, and the interatomic distance is increased by 0.05 A. (2.5%) through the effect of double repulsion. 

Solution X-ray diffraction measurements for saturated aqueous solutions of the KCl-MgCl2-6H20 and CsCl-MgCl2-6H20 double salts at 25°C reveal that magnesium(II) ions in the solutions are fully hydrated as [Mg(H20)6]2+ with a Mg-0 bond length of 208-209 pm. This is essentially the same bond length as in the double salt crystals, and the K+ and Cs+ ions have both water molecules and chloride ions in their first coordination sphere. The coordination numbers for water molecules and chloride ions around a K+ ion are 4.7 and 2.4, respectively, and those around a Cs+ ion are 4.7 and 2.0, respectively. The K+-OH2 and K+-C1 interatomic distances are found to be 227 and 320 pm, respectively, and the Cs+-OH2 and Cs + -Cl distances are 315 and 339 pm, respectively (58). The interatomic distances determined are essentially the same as those that have been reported in the literature for aqueous solutions of potassium and cesium salts. 

Interatomic Distance Figure 56. Variation of electron density in metallic magnesium with distance between two neighbouring atoms A and B by Fourier anafysis)... 

These circumstances suggest that the -electrons of the five-mem-bered ring are not incorporated in the magnesium ion, which already has an inert gas configuration, and that they therefore act as a buffer and make the interatomic distance greater. 

Fig. 4.9 Energies of free cations and of ionic compounds as a function of the oxidation state of the cation. Top Lines represent the ionization energy necessary to form the +1. +2, +3, and + 4 cations of sodium, magnesium, and aluminum. Note that although the ionization energy increases most sharply when a noble gas configuration is broken, isolated cations are always less stable in Itiifher oxidation states. Bottom Lines represent the sum of ionization energy and ionic bonding energy for hypothetical molecules MX, MXj, MXj, and MX in which the interatomic distance, r, has been arbitrarily set at 200 pm. Note that the most stable compounds (identified by arrows) arc NaX, MgXj, and AlXj. (All of the.se molecules will be stabilized additionally to a small extent by the electron affinity of X.)...

Figure 15. Interatomic distances in H-bonds (A, in parentheses), their energies (kcal/mol) of interactions, and estimated aromaticity descriptors for the /j-nitrosopheno-iate anion in two salts sodium and magnesium, respec-tiveiy. (Reprinted with permission from ref 47. Copyright 1998 Elsevier Science.)...

A third type of crown ether magnesium complex includes compounds containing an Mg-C bond to a carbon atom of the macrocycle, formed as internally com-plexed Grignard reagents 101 [375, 387, 388]. The crystal structure determination of 101 (X=Br) shows that the metal coordination is distorted pentagonal pyramidal, with bromine in apical position (Mg-Br 2.517 A) and two normal Mg-O distances (2.12 and 2.13 A) and two large interatomic distances (2.33 and 2.49 A) [388]. 

Table 4.8 Forsterite interatomic distances. There are two independent magnesium atoms in the structure, although each has essentially the same environment.

Table 4.9 Tourmaline interatomic distances the data are from a sample of dravite which is a sodium- magnesium variety. The 9- 6- and 4-coordinated groups are shown as polyhedra with the boron shown as individual atoms. In this view, the six tetrahedra are shown with their bases toward the viewer.

Consequently, in the present study, the proposed formalism is demonstrated for the rate-limiting chemical step in the OER, that is, 2[Mn=O Mn—0 ] Mn—O—O—Mn. Above, the force constants of the dioxo and peroxo species comprise fcreact and fcprod. respectively. By solving for Xjs and adding the equilibrium 0-0 bond lengths of the peroxo system, the interatomic 0-0 distance at the transition state is obtained. In what follows, the reactivity of a biomimetic binuclear molecular manganese catalyst will be contrasted by that of the binuclear Mn site supported on a magnesium oxyhydroxide rig. 

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