Аннотация:It was shown by ESR that the addn. of photochem. generated carboranyl radicals to branched fluoroalkenes affords stable spin-adducts. Reaction of B-centered radicals with 1-alkyl-2-fluoroalkenyl-o-carborane leads to stable α-carboranyl radicals. The stability of carborane conformation with respect to unpaired electron 2pz-orbitals was confirmed by negligible changes in hyperfine consts. of unpaired electron interaction with β-11B nuclei in radicals of different structure. This effect may be due to both the steric interaction and hyperconjugation of the B nucleus with the unpaired electron.