Role of 1,4-dioxan in solid adducts of hydrated metal halides. Crystal structures of hexa-aquadichloromagnesium-1,4-dioxan(1/1), trans-tetra-aquadibromonickel(II)–1,4-dioxan(1/2), and cis-diaquatetrabromotin(IV)–1,4-dioxan(1/2)

In each of the title compounds 1,4-dioxan forms extended hydrogen-bond networks between water molecules co-ordinated to the metal atoms. MgCl2·6H2O·C4H8O2, (I), space group P21/n, a= 12.15, b=7.96, c=6.86A, β= 91.23°, Z= 2; R 0.061 for 775 reflections. NiBr2·4H2O·2(C4H8O2), (II), space group I41/a, a= 9.189, c= 19.22 A, Z= 4; R 0.069 for 344 reflections. SnBr4·2H2O·2(C4H8O2), (III), space group Fdd2, a= 26.12, b= 19.07, c= 7.486 A; R 0.064 for 657 reflections. Unit-cell and space group measurements suggest that CoBr2·4H2O·2(C4H8O2), (IV)(I41/a, a= 9.19, c= 19.18 A), and SnCl4·2H2O·2(C4H8O2), (V)(Fdd2, a= 25.92, b= 18.67, c= 7.19 A), are isomorphous with (II) and (III) respectively.