Chloride, bromide, nitrate, perchlorate, bisulfate, tetrachloro -and tetra-bromo ferrate salts of a number of normallong-chain (eight or more carbon atoms per chain) aliphatic primary, secondary and tertiary amines were prepared in solid crystalline form and their infrared spectra recorded at 25'C as mulls in Nujol and as KBr pellets. Hydrogen bonding in all these salts was shown to exist by the shift of the N-H stretching frequency. With a common proton donor the magnitude of f!,. IJ was found to vary with the nature of the anion. A closely linear relationship between f!,.1J and the ionic radii and the proton affinity of the anions has been observed. From this relationship the ionic radii of FeCI. and FeSr, have been estimated. The chain length has apparently no effect on the hydrogen bond strength, contrary to the effect reported for low molecular weight (four or less carbon atoms per chain) amine salts.
Primary normal alkylammonium halides crystallize in a preferred crystallographic orientation, forming single or twinned layers. The basal spacings are related to the number of carbon atoms within the homologous series, and are doubled in the twin layers. The orientation of the hydrocarbon chains between the ionic heads is discussed.
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