The crystal and molecular structures of 9,10-dihydro-9, 10-ethano- and etheno-anthracenes

As part of our investigation on histamine receptor antagonists, the structu res of two 9-10-dihydroanthracene derivatives are reported: 4. C22H28N2; he xagonal, P6(1); a = 10.014(1), c = 34.556(7) Angstrom; V = 3001.0(7)Angstro m(3); and Z = 6; 9: C19H19N: triclinic, P-1; a = 8.427(2), b = 12.806(3), c = 15.292(3) Angstrom, alpha = 70.27(3), beta = 80.83(3), gamma = 72.98(3)d egrees; V = 1482.0(6) Angstrom(3); and Z = 4. All non-aromatic rings in bot h molecules adopt a similar conformation. However, the three six-membered r ings in the etheno-anthracene structure adopt a more regular boat form in s pite of two sp(2) carbon bridged atoms.