title: Cooperative hydrogen-bonding effects in a water square: a single-crystal neutron and partial atomic charges and hardness analysis study.
abstract: Four isomorphous complexes of formula [M(L)(4)(H(2)O)(2)]SO(4).2H(2)O (M = Co, 1a; Ni, 1b; Cu, 1c; Zn, 1d) have been isolated and characterized by single-crystal X-ray diffraction and neutron diffraction using the quasi-Laue diffractometer VIVALDI at the Institut Laue-Langevin as well as by thermogravimetric analysis. The structures contain a discrete, strongly hydrogen-bonded water tetramer which causes a significant distortion of the metal coordination sphere in each case. Partial atomic charges and hardness analysis (PACHA) calculations reveal that the shortest hydrogen bonds are not the strongest in this constrained, cyclic solid-state structure and show that the distortion at the metal center is caused by the drive to maintain the integrity of the water tetramer. The system undergoes a disorder-order transition on slow cooling that provides insight into the nature of communication between water squares.
authors.affiliation: Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, U.K.
authors.forename: David R
authors.initials: DR
authors.lastname: Turner
authors.forename: Marc
authors.initials: M
authors.lastname: Henry
authors.forename: Clive
authors.initials: C
authors.lastname: Wilkinson
authors.forename: Garry J
authors.initials: GJ
authors.lastname: McIntyre
authors.forename: Sax A
authors.initials: SA
authors.lastname: Mason
authors.forename: Andres E
authors.initials: AE
authors.lastname: Goeta
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Steed