HYDROGEN BONDING IN THE CRYSTAL STRUCTURE OF LEGRANDITE: Zn2(AsO4)(OH)(H2O)

The crystal structure of legrandite -- Zn-2(AsO4)(OH)(H2O), monoclinic, a 12.8052(3), b 7.9249(2), c 10.2173(2) angstrom, beta 104.4329(3)degrees, V 1004.13(6) angstrom(3), space group P2(1)/c, Z = 2 -- has been refined to an R-1 value of 1.2% based on 2844 unique [vertical bar F-o vertical bar > 4 sigma F] reflections measured with a Bruker D8 three-circle diffractometer equipped with a rotating-anode generator (MoKa X-radiation), multilayer optics, and an APEX-II detector. The legrandite structure is a heteropolyhedral framework of (AsO4) tetrahedra, (Zn phi(5)) square pyramids, and (Zn phi(6)) octahedra [phi = O, (OH), (H2O)] with extensive hydrogen bonding across its interstices. All hydrogen positions were located, all hydrogen bonds were assigned, and the H center dot center dot center dot O distances are in reasonable accord with the published relation between O-H stretching frequency and H center dot center dot center dot O bond-length.