title: Bonding effects and the crystal structures of (NH4)2
abstract: The crystal structures of the Tutton salts (NH4)2[Cu(H2O)6](SO4)2, diammonium hexaaquacopper disulfate, formed with normal water and isotopically substituted H2(18)O, have been determined by X-ray diffraction at 9.5 K and are very similar, with Cu-O(7) the longest of the Cu-O bonds of the Jahn-Teller distorted octahedral [Cu(H2O)6]2+ complex. It is known that structural differences accompany deuteration of (NH4)2[Cu(H2O)6](SO4)2, the most dramatic of which is a switch to Cu-O(8) as the longest such bond. The present result suggests that the structural differences are associated with hydrogen-bonding effects rather than with increased mass of the water ligands affecting the Jahn-Teller coupling. The Jahn-Teller distortions and hydrogen-bonding contacts in the compounds are compared with those reported for other Tutton salts at ambient and high pressure.
authors.affiliation: School of Chemistry, University of Western Australia, Nedlands, Australia. bnf@crystal.uwa.edu.au
authors.initials: BN
authors.lastname: Figgis
authors.initials: AN
authors.lastname: Sobolev
authors.initials: CJ
authors.lastname: Simmons
authors.initials: MA
authors.lastname: Hitchman
authors.initials: H
authors.lastname: Stratemeier
authors.initials: MJ
authors.lastname: Riley