Three-dimensional supramolecular H-bonding network in the compounds containing hexamethylenetetramine and aquated Ni(II) or Cd(II) salts

To investigate the interactions between hydrogen bond donor and acceptor giving rise to three dimensional networks, compounds [Ni(H2O)6](ClO4)2 • 2{(CH2)6N4} • 2H2O (1), [Ni(H2O)6]Cl2 • 2{(CH2)6N4} • 4H2O (2) and [Cd(H2O)4{(CH2)6N4}2](ClO4)2 • 2H2O (3) (where (CH2)6N4 = hexamethylenetetramine) have been prepared and their crystal structures were investigated. In all three complexes, the metal coordination is octahedral. The hexamine molecules are complexed in the cadmium compound, 3 but are free in the nickel salts, 1 and 2. The supramolecular structures of 1 and 2 show R44 (16) motif linking the cationic moieties with hexamine which are in turn interwoven with anionic moieties via water molecules. In contrast the supramolecular structure of 3 shows R22 (12) motif