Metal Complexes of Organic Molecules Containing Multiple Bonds

Abstract

The kinetics of the rearrangement of benzaldoxime to benzamide, catalysed by nickel acetate tetrahydrate in digol, are reported. The process is exothermic. Apparatus designed to study the rearrangement at a constant temperature and an infrared spectroscopic technique for the detection of benzamide are described.

It is found that the production of benzamide occurs in two, consecutive, psuedo-first order steps. Kinetic isotope studies reveal the first step to involve a nickel dependent cleavage of the carbon-hydrogen bond of benzaldoxime. The second step is observed to be essentially nickel independent and is suggested to be the organic rearrangement of an intermediate, postulated to be a benzimidate. It is thought that benzaldoxime exists in its anti (β) configuration prior to rearrangement. A number of related experiments are cited.

A kinetic investigation of the production of the deep blue solution (blau), found to arise under certain conditions, in aqueous solutions of potassium tetrachloroplatinite and acetonitrile, is presented. The reaction is accompanied by the release of acid. Apparatus designed to enable the reaction to be studied titratiometrically and spectrophotometrically, at constant pH and temperature is described.

A preliminary study of the ligand substitution reactions of the tetrachloroplatinite (II) ion in this system reveals the normal two-term rate law to be obeyed.

The production of the blau is found to depend upon an initial sequence of substitution reactions of platinum(II),followed by several less clearly defined processes, which arebelieved to include the oxidation of platinum (II) to platinum (IV), the hydrolysis of acetonitrile and the chelation of the resultant acetamido anion. The blau is suggested to be dihydroxybis (acetamido) platinum(IV) involved in a set of complex equilibria.

A preliminary investigation of the behaviour of cyanoacetamide towards several transition metal ions is included as an interesting area for further research.

Date of Award	Nov 1974
Original language	English