Through-space interaction between nonconjugated naphthalene and phenanthrene in a rigid molecule

Abstract

The transannular interaction between naphthalene and phenanthrene in 4H-cyclopenta[def]phenanthrene-4-spiro-7′-(6b,7a-dihydro-7H-cyclopropa[a]acenaphthylene)(1) and between naphthalene and fluorene in 6b,7a-dihydro-7H-cyclopropa[a]acenaphthylene-7-spiro-9′-fluorene (2) was studied spectroscopically and photochemically. The difference between electronic absorption of these rigid model compounds and that of their component chromophores was examined by an SCF–Cl–CNDO–MO procedure with partial through-space bonding of the nonconjugated π-systems. Satisfactory agreement between theoretically predicted absorption spectra and those determined experimentally was found for both (1) and (2) and their continuously conjugated photoproducts.