Crystal and molecular structure of (+)-(S,S ')-alpha,alpha '-(9-oxo-1,5-diphenyl-3,7-diazabicyclo[3.3.1]non-3,7-ylene)dipropionic acid

The crystal and molecular structure of (+)-(S,S')-alpha,alpha-(9-oxo-n-1,5- diphenyl-3,7-diazabicyclo[3.3.1] non-3.7-ylene)dipropionic acid (1) was det ermined by X-ray diffraction: spaer group P2(1)2(1)2(1), a = 11.277(1), b = 17.810(2), c = 21.865(2) Angstrom. Z = 8(C25H28N2O5). The structure of I w as solved by direct methods and refitted by the full-matrix least-squares p rocedure in an anisotropic approximation to R = 0.044 for 3655 independent reflections (CAD-4 automatic diffractometer, lambda CuKalpha). The structur e contains two symetrically independent molecules existing in zwitterionic form (with one protonated N atom) and having similar geometrical parameters of the bicyclic frameworks and different orientations (conformations) of t heir acid substituents. In both molecules, the bicyclic framework consists of two fused six-membered rings and has a chair-chair conformation stabiliz ed by the intramolecular II-bond N-H ... N. The carboxyl H atoms of both in dependent molecules are involved in strong intermolecular H-bonds O-H ... O , some of which are nearly symmetrical.