Computational confirmation of C5N2 observed in rare-gas matrices

The structures and vibrations of several linear centrosymmetrical isomers o f C5N2 were investigated by DFT. Tripler ((3)Sigma(g)(-)) and open-shell si nglet ((1)Sigma(g)(-)) states of NCCCCCN were found to have the lowest ener gies. The calculated frequencies and isotope shifts are in excellent agreem ent with the experimental results of prominent vibrational bands observed i n rare-gas matrices [Chem, Phys. 184 (1994) 233], thus confirming the concl usion that linear centrosymmetrical NCCCCCN was generated in rare-gas matri ces. However, the calculated results are not in reasonable agreement with t he observed frequencies of weaker bands, suggesting these weaker bands orig inate from something else. (C) 1999 Elsevier Science B.V. All rights reserv ed.