STRUCTURE OF BIS(2-AMINO-5-NITROPYRIDINIUM) DICHROMATE AS A STEP TOWARDS THE DESIGN OF EFFICIENT ORGANIC INORGANIC NONLINEAR OPTICAL-CRYSTALS

The orthorhombic crystal structure of 2C5H6N3O2+.-Cr2O72- [a = 22.454 (6), b = 15.129 (2), C = 5.189 (2) angstrom, Z = 4, orthorhombic, P2(1 )nb, D(x) = 1.866 g cm-3] has been solved using direct methods and ref ined to wR = 0.029 for 2514 reflections. This study provides a step to wards a new route to obtain non-linear optical crystals which aims at combining the highly polarizable 2-amino-5-nitropyridinium cation with inorganic anionic host matrices. The shielding effect of dichromate a nions in the building of an acentric polar framework is discussed. The structure is compared with other structures containing 2-amino-5-nitr opyridine moieties. The cations are completely or partly arranged in a 'herringbone' structure in all these frameworks.