An Extremely Porous Hydrogen-Bonded Framework Composed of d-Penicillaminato Co(III)2Au(I)(3) Complex Anions and Aqua Cobalt(II) Cations: Formation and Stepwise Structural Transformation.

A unique example of a hydrogen-bonded ionic solid with a porosity of 80 %, [Co(H2O)6]3 [Co2Au3 (d-pen-N,S)6]2 (1; d-H2 pen=d-penicillamine), composed of [Co(H2O)6](2+) cations and [Co2Au3 (d-pen-N,S)6 ](3-) anions, is reported. Solid 1 was kinetically produced and was then transformed stepwise into two more thermodynamically stable solids with lower porosities, [Co(H2O)4 ][Co(H2O)6]2 [Co2Au3 (d-pen-N,S)6]2 (2) and [Co(H2O)4]3 [Co2 Au3 (d-pen-N,S)6]2 (3), through the coordination of the free carboxylate groups in [Co2Au3 (d-pen-N,S)6](3-) to Co(II) centers. Solids 1-3 were structurally characterized, and the selective adsorption of small molecules into their pores was investigated.