ESR AND RING INVERSION OF TETRALIN-1-YL AND ESR OF RELATED BENZYL RADICALS

The tetralin-1-yl radical 1 was generated in solution by hydrogen abstraction from tetralin by photoexcited benzophenone. The proton hyperfine splittings and the g value are reported from -69 to 146°C. An alternating line width effect occurs and is ascribed to ring inversion in the saturated portion of the radical. Line widths and amplitudes were analyzed at low and high inversion rates (near -50 and 130°C, respectively) to yield values of the ring inversion rate. Arrhenius parameters for the inversion are E = 30 kJ/mol ±12% and log k = 13.1 ± 0.7. Two azimuthal angles which indicate the extent of ring puckering are determined from the proton splittings at -69°C. The room temperature hyperfine constants and g values of m- and o-xylyl and α-methylbenzyl are reported and support the assignment of proton splittings in tetralin-1-yl. The methyl group splittings in m-and o-xylyl are smaller than expected from comparison with related radicals. © 1979 American Chemical Society.