Distance in crystals

Patterson A L 1934 A Fourier series method for for the determination of the components of interatomic distances in crystals Phys. Rev. 46 372-6... 

Covalent Radii of Atoms and Interatomic Distances in Crystals containing Electron-Pair Bonds. 

In Table VII radius sums from Table VI are compared with observed distances from band spectral data. Agreement to within 0.01 or 0.02 A is usually found in the exceptional case H2C0 the experimental value is not very accurate. In Table VIII a similar comparison is made with observed distances in crystals. These distances depend in all cases on... 

Comparison of Radius Sums from Table VI with Observed Distances in Crystals. 

The Fluorite Structure.—In Table XI are given the observed interatomic distances in crystals with the fluorite structure. There is good... 

A crystallographic scale of acidity has been developed. Measuring the mean C—H O distances in crystal structures correlated well with conventional P a(DMSO) values. An ab initio study was able to correlate ring strain in strained hydrocarbons with hydrogen-bond acidity. ... 

Fig. 2-3. Formation of electron energy bands in constructing a solid crystal X from atoms of X ro = stable atom-atom distance in crystal BB = bonding band ABB = antibonding band e, = band gap.

Fig. 2-12. Electron energy band formation of silicon crystals from atomic frontier orbitals number of silicon atoms in crystal r = distance between atoms rg = stable atom-atom distance in crystals, sp B8 = bonding band (valence band) of sp hybrid orbitals sp ABB = antibonding band (conduction band) of sp hybrid orbitals.

The van der Waals radius is defined as a nonbonded distance of closest approach, and these are calculated from the smallest interatomic distances in crystal structures that are considered to be not bonded to one another. Again, these are average values compiled from many crystal structures. If the sum of the van der Waals radii of two adjacent atoms in a structure is greater than the measured distance between them,... 

A set of values of tetrahedral covalent radii 7 for use in crystals of these types is given in Table 7-13 and represented graphically in Figure 7-7. These values were obtained from the observed interatomic distances in crystals of these tetrahedral types and of other types in which the atom of interest forms four covalent bonds with neighboring atoms which surround it tetrahedraliy. For example, in pyrite, FeS. each sulfur atom is surrounded tetrahedraliy by three iron atoms and one sulfur atom, with all of which it forms essentially covalent bonds (Fig. 7-8) the substance is a derivative of hydrogen disulfide, H2S2. That the Fe—S bonds are essentially covalent is shown by the magnetic eri-... 

In Chapter 11 there will be given a discussion of the observed interatomic distances in crystals of the metallic elements and an account of the derivation from them of a set of values of single-bond metallic radii. These values are shown in Table 7-18. They refer to single covalent bonds for which the bond orbitals have the same hybrid character as in the metals themselves, as discussed in Chapter 11. The relation bc-... 

Tabus 13-12.—Intebionic Distances in Crystals M++X— with the Sodium Chloride Arrangement... 

Table I. Solid State H NMR Chemical Shifts of Imidazoles and Hydrogen Bonding Distances in Crystals...

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