Synthesis, crystal structures and thermal behaviour of organic-inorganic hybrids incorporating a chiral diamine

Abstract

A series of noncentrosymmetric metal sulfates [R-C 5H 14N 2][M II(H 2O) 6](SO 4) 2 and [S-C 5H 14N 2][M II(H 2O) 6](SO 4) 2 (M II = Mn (1, 2), Fe (3, 4), Co (5, 6) and Ni (7, 8)) have been synthesized by slow evaporation conditions through the use of enantiomorphically pure sources of either R-2-methylpiperazine (R)-C 5H 12N 2 or S-2-methylpiperazine (S)-C 5H 12N 2. These materials crystallize in the polar, noncentrosymmetric space group P2 1 (No. 4), crystal class 2 (C 2). Isolated [M II(H 2O) 6] 2+, [(R)-C 5H 14N 2] 2+ or [(S)-C 5H 14N 2] 2+ cations and (SO 4) 2- anions linked together via two types of hydrogen bonds, O w-H w⋯O and N-H⋯O, from which supramolecular structures are formed. The use of single enantiomer of either R-2-methylpiperazine or S-2-methylpiperazine precludes inversion symmetry within the crystal lattices and forces crystallization in noncentrosymmetric structures. Compounds 1-8 were characterized using single crystal X-ray diffraction, infrared spectroscopy and thermal analyses. The structural arrangements and the intermolecular interactions such as hydrogen-bonding are discussed. © 2011 Elsevier B.V. All rights reserved.