Paramagnetic intermediates in the photolysis of 7-silanorbornadiene studied by means of spin chemistry method

The influence of an external magnetic field on the yield of photo-decomposition products of 7,7′-dimethyl-7-silanorbornadiene derivative has been detected in laser pulse photolysis experiments. The observations of magnetic field effects alterations in the presence of scavengers, O 2 and PPh 3 , in combination with 1 H-CIDNP data form the basis for the identification of the structure of paramagnetic intermediates involved in the process. It has been shown that magnetic field effects originate in biradical intermediates. These species result from both endocyclic SiC bond cleavage in the initial compound and the reaction of dimethylsilylene (in a singlet or a triplet excited state) with starting 7-silanorbornadiene. To explain the influence of O 2 upon the magnetic field effects, the reversible formation of oxygen complex with biradical species has been suggested.