Structural characterization of polymeric potassium salts with 2-thiobarbituric acid: influence of organotin(IV) chlorides on potassium cation solvation

Slow evaporation of the filtrate derived from the reaction in water between 2-thiobarbituric acid (H(2)TBA) and equimolar amount of potassium hydroxide results in the formation of crystals of two coordination polymers: unhydrated [K(mu(3)-S,O-HTBA)](n) (1) and hydrated [K(mu(2)-S,O-HTBA)(mu(2)-S,O-H(2)TBA)(mu-H2O)](n) (2), which depend on the absence (1) or presence (2) of methanol solutions of organotin chloride. The hydrate 2 was isolated from the filtrates when di-n-butyltin dichloride, dimethyltin(IV) dichloride, diphenyltin(IV) dichloride, tri-n-butyltin chloride, or triphenyltin(IV) chloride were used during the reaction. The crystal structures show that coordination of potassium occurs through the S and O donors. The potassiums have distorted tetragonal bipyramidal and distorted cubic coordination environments in 1 and distorted square antiprism coordination in 2. Both structures exhibit intermolecular N-H center dot center dot center dot O hydrogen-bond interactions, which form TBA chains while the water in 2 produces a richer hydrogen-bonded structure.