Single-Crystal Transformation and Catalytic Properties of New Hybrid Perhalidometallates

Abstract

Two new organic-inorganic salts of perhalidometallates with protonated organic amine cations have been synthesized and characterized by X-ray diffraction and thermal analysis. (CHBMAH(2))ZnBr4 center dot 3/2H(2)O 1 and (CHBMAH(2))ZnCl4 4 [(CHBMAH(2))(2+): 1,3-cyclohexanebis(methylammonium)] were obtained in single-crystal form. The crystal packing in all of the obtained compounds is governed by the formation of various non-covalent intermolecular forces between tetrahalidometallate anions and organic cations, assisted by water molecules in the hydrates. Hirshfeld surface analysis denotes that the most important contributions to the crystal packing are X center dot center dot center dot H/H center dot center dot center dot X (X: Cl, Br, I) and H center dot center dot center dot H interactions. Interestingly, the compound 1,3-cyclohexanebis(methylammonium)tetrachloridozincate (II) dihydrate, (CHBMAH(2))ZnCl4 center dot 2H(2)O 2, undergoes thermally-triggered single-crystal-to-single-crystal (SCSC) transformation upon dehydration to produce a supramolecular solid compound, 1,3-cyclohexanebis(methylammonium) tetrachloridozincate (II), (CHBMAH(2))ZnCl4 4. The SCSC transformation causes changes in the lattice parameters and a structural rearrangement. Furthermore, the catalytic properties of (CHBMAH(2))ZnCl4 center dot 2H(2)O 2 and (CHBMAH(2))CdI4 center dot 2H(2)O 3 have been explored in the acetalization process using various uncommon alcohols, beyond methanol or ethanol, for the first time in the literature, with outstanding results, and opening the door to the formation of alternative acetals.