PHOTOLYSIS OF SUBSTITUTED BENZENEDIAZONIUM SALTS - SPIN-SELECTIVE REACTIVITY OF ARYL CATIONS

The photolysis of a series of substituted benzenediazonium salts was s tudied by low-temperature and time-resolved spectral methods and by an alysis of products formed in alcohol solutions at room temperature. Th e spin multiplicity of the ground state aryl cations formed by nitroge n loss from the diazonium salt is known to depend on the nature of the substituent. The low-temperature spectroscopic experiments confirm a triplet ground state when the cation contains a p-amino group. These t riplet cations are detected directly in fluid solution for the first t ime, and their lifetimes are estimated. Analysis of products reveals t hat these cations react predominantly from the initially formed single t state rather than their triplet ground state.