The trihydrated sodium salt of the herbicide picloram comprises a cationic μ 2-aqua-bridged chain structure that is linked to the picloramate anions through amine N—H⋯O and water O—H⋯O and O—H⋯N hydrogen bonds.
In the structure of the title complex, {[Na(H 2O) 3](C 6H 2Cl 3N 2O 2)·3H 2O} n , the sodium salt of the herbicide picloram, the cation adopts a polymeric chain structure, based on μ 2-aqua-bridged NaO 5 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 R 4 4(8) motif, resulting in an overall three-dimensional structure.