The structure of two solid zinc dipicolinate complexes

When equal amounts of dipicolinic (pyridine-2,6-dicarboxylic) acid and zinc sulfate were incubated at 277K, two different zinc dipicolinate compounds of composition Zn 2 (C 7 H 3 NO 4 ) 2 .7H 2 O and Zn(C 7 H 4 NO 4 ) 2 .3H 2 O were formed. In both compounds the coordination polyhedra are distoted octahedra with Zn-N=2.003-2.016A and Zn-O=2.078-2.349A. The compounds crystallize in the monoclinic space group P2 1 /c with four formula units in the unit cell.