The chemistry of the salts of strong acids

Baillie, Matthew James (1965) The chemistry of the salts of strong acids. PhD thesis, University of Glasgow.

Abstract

Solutions of the First Row Transition Metal salts of some strong acids (perehlorates, trifluoro-acetates and tetrafluoroborates) have been prepared in non-aqueous solvents viz. ether, benzene and nitromethane. Two methods of preparation have been employed.1. Dehydration of the hydrates. Hydrated salts of the above acids were prepared by adding excess transition metal oxide, hydroxide or carbonate to an aqueous solution of the strong acid. Recrystallisation was carried out to ensure purity. Dehydration has been attempted by thermal decomposition using a thermogravimetric balance. In many cases, water was completely removed but some decomposition of the anhydrous strong acid salt accompanied the dehydration., The decomposition products e.g. fluorides and chlorides were insoluble in the organic solvents used and solutions could be prepared from the mixtures produced after the dehydration stage. Removal of water using 2,2 dimethoxypropane has also been attempted. Excess of the reagent was added to the hydrate and the mixture stirred for varying periods of time. The reaction proceeded according to the epilation CH3C(OCH3 )2CH3 + H2O = 2 CH3OH + (CH3)2CO. Anhydrous compounds again gave solutions although some doubt exists, due to the decomposition products of the dimethoxypropane, as to the exact nature of the solvent system. 2. Metathesis., The anhydrous silver salt of the strong acid was dissolved in the organic solvent and excess anhydrous metal halide or metal added. After some time, ranging from one week to two months, the silver halide or silver metal was completely precipitated producing a solution of the transition metal salt. For the dipositive metals, two distinct species have been identified in solution corresponding to the formulae M(C1)X and MX2, where X is the strong acid anion. In the tripositive series, the evidence points to the formula MX3 only. Solutions prepared from the dehydration reactions were similar to those obtained for the MX3 or MX3 types. Metals studied were zinc (ll), copper (ll), titanium (lll), vanadium (ill), chromium (lll), iron (ll), iron (lli), nickel (ll) and cobalt (ll). The solutions have been examined by means of ultra-violet and near infra-red spectroscopy, magnetic and conductivity measurements and by analysis., Solid trifluoroacetates, both in chloro and bis forms have been obtained in the divalent series. Only the tris compound could be isolated from the trivalent metal solutions. These solids resulted from the removal of solvent from nitro- methane solution and were studied by similar methods to those used for solutions. Attempts to prepare the anhydrous compound from perehlorate and tetrafiuoraborate solutions always resulted in considerable decomposition in the latter stages of solvent removal. The results have established that the compounds formed in solution are weak-fields, octahedral complexes in which the solvent occupies at least two of the coordination positions round the central metal atom and in which there is considerable anion-cation interaction. Some attempts have been made to prepare solid, strong acid salts of some Group VA trivalent elements by metathesis involving the anhydrous silver salt and the halide as before. Quantitative precipitation of silver halide resulted, but in some cases the solid compound could not be Isolated in a pure state.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: D WA Sharp
• Keywords: Inorganic chemistry
• Date of Award: 1965
• Depositing User: Enlighten Team
• Unique ID: glathesis:1965-72240
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 24 May 2019 15:12
• Last Modified: 24 May 2019 15:12
• URI: https://theses.gla.ac.uk/id/eprint/72240