The crystal structure of 4-aminopyridinium heptamolybdate hexahydrate

Abstract
The title compound, (C 5 H 7 N 2 ) 6 [Mo 7 O 24 ] · 6H 2 O, crystallizes in the monoclinic system, space group P 2 1 / c , a = 14.345(2), b = 19.662(2), c = 18.909(5) Å, β = 95.47(1)°, V = 5309(2) Å 3 , Z = 4, D o = 2.16(1), D x = 2.17 Mg m −3 . The crystal structure has been refined to R = 0.041 and R w = 0.045 for 4311 observed reflexions. The unit cell contains [Mo 7 O 24 ] 6− discrete polyanions linked to 4-aminopyridinium cations and water molecules through mono- and bifurcated hydrogen bonds. Some of these hydrogen bonds may play an important role in the possible UV-induced photochromism of this compound.