Hydroxyl ions, bond angle

The Raman spectra of nitric and deuteronitric acids have been examined by Redugh and Nielsen who found that the characteristic frequencies of the hydroxyl oup were changed by the substitution of deuterium for hydrogen. Solution in water brings about the formation of the nitrate ion in which all the oxygen atoms arc identical and the O— N—O bond angle... 

Figure 5. Schematic representation in two dimensions of a dehydrated but fully hydroxylated colloidal silica particle. The fourth oxygen coordinated with Si is above or below the plane of the paper. The figure is only a diagram, not a model. In an amorphous silica model the Si-O-Si bond angle may vary, but the Si-O distances are constant each oxygen ion is linked to not more than two cations the coordination number of oxygen ions about the control cation is 4 or less oxygen tetrahedra share comers, not edges or faces and at least two comers of each tetrahedron are shared.

P2i/c Z = 4 Dx = 1.56 R = 0.073 for 2,433 intensities. The Mg2+ ion is octahedrally coordinated by four water molecules and two vicinal hydroxyl groups, leading to small distortions of the torsion angles of the cyclohexane ring, 50-60°. The Cl- ions are four- and five-coordinated by water and hydroxyl oxygen atoms. There is also extensive, intermolecular hydrogen-bonding. 

The intramolecular Oeq 1 to Oax2 distance is shortened 0.33 A and that for Oeq3 to Oax2,0.11A from a normal value of 2.89 A [99]. The decrease in the C-C-0 angles for the C1-C2 bond could be an effect of the magnesium ion attraction to the hydroxyl groups. The torsion angles for bond C1-C2 differ by as much as 14° from those of myo-inositol. 

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