The action of nitrogen dioxide and nitric oxide on humulene, C15H24. X-Ray crystallographic determination of the stereochemistries and conformations of humulene nitrosite, dinitrohumulene, and nitronitratohumulene

Abstract

The stereochemistries and conformations of humulene nitrosite (2), dinitrohumulene (3), and nitronitratohumulene (4) have been determined by X-ray analyses of their crystal structures. The compounds are shown to result from cis addition to humulene (1). The common ring conformation in compounds (2), (3), and (4) differs from that in humulene. A spread of C–C–C angles in the eleven-membered rings indicates steric strain and these results are reproduced in force-field calculations on the hexamethylcycloundecadiene (5). Crystallographic data are humulene nitrosite, a= 6.484(2), b= 18.139(8), c= 14.294(3)Å, β= 101.33(2)°, Z= 4, space group P2₁/n; dinitrohumulene, a= 6.422(2), b= 18.177(2), c= 14.218(2)Å, β= 100.69(2)°, Z= 4, space group P2₁/n; nitronitratohumulene, a= 7.665(2), b= 11.908(2), c= 18.170(4)Å, Z= 4, space group Pc2₁n. X-Ray intensity measurements were made on an automatic four-circle diffractometer and least-squares adjustment of the atomic co-ordinates and thermal parameters converged at R 0.071 for compound (2), 0.042 for compound (3), and 0.052 for compound (4).