Crystal structures of two new divalent transition-metal salts of carb-oxy-benzene-sulfonate anions.

Hexa-aqua-nickel(II) bis-(3-carb-oxy-4-hy-droxy-benzene-sulfonate) dihydrate, [Ni(HO)][CH(COH)(OH)SO]·2HO, (I), crystallizes in the triclinic space group with the nickel(II) aqua complexes on centers of inversion. The carboxyl-ate group is protonated and neither it nor the sulfonate group is involved in direct coordination to the metal ions. The structure consists of alternating layers of inorganic cations and organic anions linked by O-H⋯O hydrogen bonds that also include non-coordinated water mol-ecules of crystallization.

The low-temperature triclinic crystal structure of silver 3-sulfo-benzoic acid.

Poly[(μ-3-carboxybenzenesulfonato)silver(I)], Ag(OSCHCOH) or [Ag(CHOS)] , has been found to undergo a reversible phase transition from monoclinic to triclinic between 160 and 150 K. The low-temperature triclinic structure (space group ) has been determined at 100 K. In contrast to the reported room temperature monoclinic structure, in which the nearly equivalent carboxyl-ate C-O distances indicate that the acidic hydrogen is randomly distributed between the O atoms, at 100 K the C-O (protonated) and C=O (unprotonated) bonds are clearly resolved, resulting in the reduction in symmetry from 2/ to .