Acid-Driven Dimensionality Control of Cd(II) Complexes: From Discrete Double Open Cubane to One- and Three-Dimensional Networks

Reaction of CdCl2 with hep-H [hep-H = 2-(2-hydroxyethyl)pyridine] in MeOH at 298 K yields the double open cubane tetramer [Cd-2(mu-Cl)(2)(mu(3)-Cl)(hep-H)(2)Cl](2) (1). 1 on reaction with methanolic HCl, HNO3, and H2SO4 transforms into a one-dimensional (ID) polymeric chain [Cd(mu(2)-Cl)(2)(Cl)(hep-H-2)](n) (2), ribbon-shaped polymeric structure [[Cd5Cl12(H2O)(3)]-(hep-H-2)(2)](n) (3), and three-dimensional network [Cd(SO4)(H2O)](n) (4) with topology seh-4,6-C2/c net, respectively. The similar reactions of CdCl2 with other pyridine alcohols such as hmp-H [hmp-H = 2-(2-hydroxymethyl)pyridine] and hpp-H [hpp-H = 2-(2-hydroxypropyl)pyridine] yield ID polymeric chains [Cd(mu(2)-Cl)(2)(hmp-H)](n) (5) and [Cd(mu(2)-Cl)(2)(hpp-H)] (6), respectively. Similar to 1, upon treatment with methanolic HCl 5 and 6 also transform into respective ID polymeric chains [Cd-2(mu(2)-Cl)(4)-(Cl)(2)(hmp-H-2)(2)](n) (7) and [Cd(mu(2)-Cl)(2)(Cl)(hpp-H-2)](n) (8), analogous to 2. However, their reactions with methanolic HNO3 and H2SO4 result in nonisolable products. In 1, 5, and 6, the pyridine alcohols are bonded to Cd(II) in bidentate fashion via their O and N atoms, whereas in 2, 7, and 8 due to protonation of pyridine nitrogen these ligands are bonded in a monodentate fashion via the alcoholic O atom.