Structure of bis(2-amino-5-nitropyridinium) dichromate as a step towards the design of efficient organic–inorganic non-linear optical crystals

The orthorhombic crystal structure of 2C 5 H 6 N 3 O 2 + .- Cr 2 O 7 2- (a=22.454 (6), b=15.129 (2), c=5.189 (2) A, Z=4, orthorhombic, P2 1 nb, D x =1.866 g cm -3 ] has been solved using direct methods and refined to wR=0.029 for 2514 reflections. This study provides a step towards 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 anions in the building of an acentric polar framework is discussed