SYNTHESIS AND STRUCTURES OF LAYERED METAL SULFONATE SALTS

A series of divalent transition metal benzenesulfonates, M(C6H5SO3)2.6H2O where M = Mn, Co, Ni and Zn, have been prepared from reactions of metal salts and sodium benzenesulfonate in aqueous solution. The products have been characterized by single crystal X-ray diffraction techniques (monoclinic, space group P2(1), Z = 2, (M = Co) a = 7.017(2), b = 6.324(2), c = 22.468(4) angstrom, beta = 93.70(3)-degrees, V = 995.0(4) A3, R(F) = 0.052 for 1270 observations and 159 variables). These materials are isostructural and contain alternating layers of benzenesulfonate anions and [M(H2O)6]2+ cations. The reaction of sodium 4-hydroxybenzenesulfonate and nickel(II) chloride in aqueous solution yielded crystals of Ni(HOC6H4SO3)2.8H2O. This compound is also monoclinic, space group P2(1)/c, Z = 4, a = 11.759(2), b = 7.262(4), c = 25.361(1) angstrom, beta = 94.353(8)-degrees, V = 2159(1) angstrom3, R(F) = 0.043 for 2090 observations and 284 variables. The structure is similar to that of the unfunctionalized benzenesulfonates in that it contains layers of sulfonate anions and hexaaquanickel cations. There are also two non-coordinated water molecules of hydration associated with the aqua ions. The presence of the hydroxy groups on the phenyl rings allows for enhanced hydrogen bonding between the layers. The crystal structure of the starting sodium 4-hydroxybenzenesulfonate, Na2(HOC6H4SO3)2.4H2O, has also been determined (monoclinic, space group P2(1)/a, Z = 4, a = 8.029(4), b = 10.086(3), c = 23.185(2) angstrom, beta = 94.07(2)-degrees, V = 1873(1) angstrom3, R(F) = 0.042 for 2198 observations and 254 variables) and it, too, has alternating layers of sulfonate ions and hydrated cations. In this structure, the sodium ions do coordinate directly to the sulfonate oxygen atoms. The crystal structures of these materials are discussed in relation to recently reported layered metal phosphonates.