title: New LaMAsH(x) (M = Co, Ni, or Cu) arsenides with covalent M-H chains.
abstract: A new series of tetragonal LaPtSi-type mixed-anion arsenides, LaMAsH(x) (M = Co, Ni, or Cu), has been synthesized using high-temperature and high-pressure techniques. The crystal structure of these intermetallic compounds determined via powder neutron diffraction is composed of a 3D framework of three connected planes with the La ions filling the cavities in the structure. Each late transition-metal ion M, all of which have relatively large electronegativities, behaves like a main group element and forms a planar coordination configuration with three As ions. The trigonal-bipyramidal coordination adopted by the H in the cavity, HM2La3, is compressed along the C3 axis, and unusual M-H chains run along the x and y directions, reinforcing the covalent framework. These chains, which are unique in solids, are stabilized by covalent interactions between the M 4s and H 1s orbitals.
authors.affiliation: Materials Research Center for Element Strategy, Tokyo Institute of Technology , 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizoguchi
authors.forename: SangWon
authors.initials: S
authors.lastname: Park
authors.forename: Haruhiro
authors.initials: H
authors.lastname: Hiraka
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Ikeda
authors.forename: Toshiya
authors.initials: T
authors.lastname: Otomo
authors.forename: Hideo
authors.initials: H
authors.lastname: Hosono