Phenyl-Substituted Thiaboranes─Linked 2D and 3D Aromatics as Noncovalent Organic Framework Materials

A series of 12-phenyl-<i>closo</i>-thiaboranes (12-(4-X-C₆H₄)-<i>closo</i>-1-SB₁₁H₁₀, where X = OMe (<b>2</b>), X = SMe (<b>3</b>), X = Ph (<b>4</b>), and X = NMe₂ (<b>5</b>)) has been prepared. Except for <b>2</b>, all compounds exhibit a chalcogen bond of thiaborane to the phenyl ring or the neighboring molecule as major supramolecular structural motif. <b>5</b>, having the strongest (-12.47 kcal/mol) structure-making intermolecular interaction via noncovalent S···π(phenyl) chalcogen bond, was crystallized from different solvents in the form of various solvatopolymorphs. <i>n</i>-Hexane and diethyl ether can be removed from <b>5</b> easily upon the formation of a porous material with large cavities (up to 20.5% of the unit cell). This first stable and useful noncovalently bound organic framework material with an ultramicroporous structure exhibits a molecular sieve effect. The selective and repeatable adsorption of CO₂ to the material crystallized from <i>n</i>-hexane was explained on the basis of cooperative and consecutive machine-like molecular interactions of quadrupolar CO₂ molecule with B-H and amino groups inside rectangular cavities.