The competition between positions C 1 and C 3 in homoadamantane upon oxidation was studied both theoretically and experimentally. B3PW91 and MP2 calculations in the 6-31+G* basis were used to study the structure of the homoadamantane radical-cation and its complexes with acetonitrile. The reaction was found to proceed predominantly at the homoadamantane C 1 position in the reaction with photoexcited 1,2,4,5-tetracyanobenzene.Petroleum and natural gas are the source of virtually all types of saturated hydrocarbons, from linear to polycyclic, but at least 90% of this valuable raw material is used as fuel. The use of saturated hydrocarbons in organic synthesis is limited in light of the low selectivity of their transformations. Reactions with radical reagents lead to complex product mixtures [1], while preparation using metal complexes or peroxo compounds is difficult [2].Methods for the functionalization of saturated hydrocarbons based on electrophilic and oxidative transformations involving cation or radical-cation intermediates hold promise. Radical-cation intermediates may be significantly stabilized both by charge and spin delocalization [3] and solvation. Depending on their symmetry, alkanes undergo Jahn-Teller distortion upon ionization, whose analysis depends decisively on the calculation methods used. Thus, only recently, the structure of the methane radical-cation was reliably interpreted in C 2v symmetry with two elongated C-H bonds [4]. The ionization of linear alkanes more complicated than methane such as ethane and propane has also been studied recently [2]. The structures of cyclic alkane radical-cations provide for more significant spin and charge delocalization. We have previously carried out both theoretical and experimental studies of the radical-cations of adamantane and its alkyl derivatives [5], cubane [2], protoadamantane, propellanes [7], and rotanes [8]. The suitability of the calculation methods selected has recently found experimental support for higher diamondoids [9].The ionization potential of alkanes is usually high (190-240 kcal/mol). Thus, the generation of alkane radical-cations requires the use of strong outer-sphere one-electron oxidants in photochemical (PET) or chemical (CET) one-electron transfer (SET) [2]. The electron affinity of the electrophiles usually employed for the oxidative activation of alkanes is rather high (200-350 kcal/mol) and the transformations proceed as inner-sphere hydrogen-bonded electron transfer in linear transition 246 0040-5760/09/4504-0246