Crystal structure of poly[[di-μ2-aqua-aquasodium] 4-amino-3,5,6-trichloropyridine-2-carboxylate trihydrate], the sodium salt of the herbicide picloram

In the structure of the title complex, {[Na(H2O)3](C6H2Cl3N2O2)·3H2O}n, the sodium salt of the herbicide picloram, the cation adopts a polymeric chain structure, based on μ2-aqua-bridged NaO5 trigonal–bipyramidal complex units which have, in addition, a singly bonded water molecule. Each of the bridges within the chain, which extends parallel to the a axis, is centrosymmetric, with Na...Na separations of 3.4807 (16) and 3.5109 (16) Å. In the crystal, there are three water molecules of solvation and these, as well as the coordinating water molecules and the amino group of the 4-amino-3,5,6-trichloropicolinate anion, are involved in extensive inter-species hydrogen-bonding interactions with carboxyl and water O atoms, as well as the pyridine N atom. Among these associations is a centrosymmetric cyclic tetrawater R44(8) motif, resulting in an overall three-dimensional structure.

Abstract licence: CC BY

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