where X may be CI or Br). The chemical shifts for complexes involving more than one type of halide are used to analyse the effect of halide on Spt in different situations. The platinum chemical shift is shown to be relatively insensitive to the substituents on the donor atoms and to be useful in the identification of the nature of platinum complexes. The results for [PtX,L]-can be reconciled with the theoretical predictions if the covalency of the metal-ligand bond is taken into account.

The use of molecular oxygen as a spin trap in rigid glassy hydrocarbon media at 77 K is investigated. By slight warming of the matrix, oxygen is found to effectively scavenge the isolated alkyl radicals produced by γ-irradiation to give RO2•, but does not react with radical pairs lying in the ionization tracks. The yield of scavengable radicals in 3MP is determined and compared to the findings of other workers. The butyl radical yields for γ-irradiated 1.0 mol l−1 butyl chlorides in 3MP are found to be: t-BuCl, 5.8; i-BuCl, 5.1; 2-BuCl, 4.9; and 1-BuCl, 2.2. Alkyl radicals cannot be recovered from either RO2 or BuO2 by uv photolysis due to solvent abstraction reactions, or because of photon induced reactions of the alkyl radicals. Photolysis of the butyl radicals themselves at 253.7 nm give rise to decomposition and solvent abstraction reactions.

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