Studies in X-ray Crystallography : I. Calcium Chloride Hexahydrate. II. Hexamethylene Tetramine Complexes with Metal Halides

Citation

Ordway, Fred Delancy, Jr. (1949) Studies in X-ray Crystallography : I. Calcium Chloride Hexahydrate. II. Hexamethylene Tetramine Complexes with Metal Halides. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/15v1-gm05. https://resolver.caltech.edu/CaltechTHESIS:06012025-103610682

Abstract

I. The crystal structure of calcium chloride hexahydrate has been determined by means of Patterson syntheses and stereochemical consideration of the atomic positions allowed by possible space groups. The parameters were determined from peaks in the Patterson syntheses, which were well resolved.

This determination confirms the conclusions of Jensen (7,8), who used a method of successive Fourier syntheses to arrive at the structure of the alkaline earth hexahydrates and to obtain approximate parameters for strontium chloride hexahydrate, but did not refine these parameters.

The results of this investigation were as follows:

Space group: D²₃-C321

Unit cell: a = 7.80 Å., c = 3.95 Å.; contains one molecule

CaCl₂·6H₂O.

Atomic positions: Ca at 1(a) 0 0 0;

Cl at 2(d) ⅓ ⅔ z, ⅔ ⅓ z, z = 0.576

0_I at 3(e) x 00, 0 x 0, x x 0, x = 0.313

0_II at 3 (f) x 0 ½ , 0 x ½, x x ½, x = -0.218

The bonding within the crystal is discussed in the light of the observed interatomic distances.

II. The structures of certain complexes of metal halides with hexamethylene tetramine, C₆H₁₂N₄, have been investigated.

The compound SnCl₄·4C₆H₁₂N₄ and the isomorphous TiCl₄·4C₆H₁₂N₄ have space group C⁵_3v-R3m. The triply primitive hexagonal unit cell has a = c = 8.95 Å. It contains three hexamethylene tetramine molecules and three chlorine atoms. The centers of the hexamethylene tetramines and of the chlorines form two interpenetrating rhombohedral lattices, separated by half the rhombohedral body diagonal. The tin atoms are probably distributed randomly among the gaps between the larger atoms.

the compounds MnCl₂·2C₆H₁₂N₄ and ₂·2C₆H₁₂N₄ give powder photographs considerably different from each other. The former has Laue symmetry D_2h, a = 11.86 Å., b = 21.92 Å., c = 7.23 Å. The lattice is primitive. There is no glide plane normal to a, but possibly an n glide normal to b and probably a b glide normal to c.

A complex of hexamethylene tetramine with SnCl₂ gave the same powder pattern as SnCl₄·4C₆H₁₂N₄. A compound with SbCl₃ gave the same pattern with a few additional lines. The formulas of the complexes are reported (7) to be SnCl₂·2C₆H₁₂N₄ and SbCl₃·3C₆H₁₂N₄.

The main factors determining the structures of these compounds seem to be packing of the anions with hexamethylene tetramine molecules and interactions among the letter as in crystals of the pure compound .

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