Layered solids based on second-sphere coordination interactions: synthesis, spectroscopic characterization, crystal structure and packing of two copper(II) naphthalene-2-sulfonates

[Cu(H2O)6](C10H7SO3)21 was obtained from reaction of CuCO3·Cu(OH)2 and naphthalene-2-sulphonic acid in aqueous medium in 1:4 molar ratio. It crystallizes in the monoclinic space group P21/n with a=7.0582(3) Å, b=6.2666(3) Å, and c=27.1420(10) Å, β=92.678(4)°, Z=2. The structure was determined from 1986 observed reflections and refined to R=0.033. When ethylenediamine was added to hexaaquacopper(II) naphthalene-2-sulfonate dissolved in water, [Cu(en)2(H2O)2](C10H7SO3)22 was obtained which crystallizes in the triclinic space group P1¯ with a=7.1491(5) Å, b=7.1949(5) Å, and c=14.6500(10) Å, α=99.025(6)°, β=98.976(6)°, and γ=104.262(6)°, Z=1. The structure was determined from 2296 observed reflections and refined to R=0.0313. X-ray structure determination of 1 revealed an ionic structure consisting of [Cu(H2O)6]+2 and two naphthalene-2-sulfonate anions while that of 2 contains [Cu(en)2(H2O)2]2+ cation and two naphthalene-2-sulfonate anions. Characteristic for the studied crystals is the alternated-layer arrangement of complex cations and naphthalene-2-sulfonate anions, linked together via hydrogen bonding, and the presence of a particularly robust R22(8) hydrogen-bonding motif that joins the complex cation with two oxygen atoms of the same sulfonate group. Elemental analyses, IR, UV/vis spectroscopic studies are consistent with the structures revealed by X-ray structure determination.