Materials Data on LaMg2NiH7 by Materials Project
LaMg2NiH7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to five H1- atoms. There are a spread of Mg–H bond distances ranging from 1.95–2.30 Å. In the second Mg2+ site, Mg2+ is bonded to six H1- atoms to form distorted MgH6 pentagonal pyramids that share corners with two equivalent MgH6 pentagonal pyramids and corners with three equivalent NiH4 tetrahedra. There are a spread of Mg–H bond distances ranging from 1.89–2.17 Å. In the third Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six H1- atoms. There are a spread of Mg–H bond distances ranging from 1.96–2.38 Å. In the fourth Mg2+ site, Mg2+ is bonded to six H1- atoms to form distorted MgH6 pentagonal pyramids that share corners with two equivalent MgH6 pentagonal pyramids and corners with three equivalent NiH4 tetrahedra. There are a spread of Mg–H bond distances ranging from 1.90–2.18 Å. There are two inequivalent La2+ sites. In the first La2+ site, La2+ is bonded in a 12-coordinate geometry to twelve H1- atoms. There are a spread of La–H bond distances ranging from 2.32–2.76 Å. In the second La2+ site, La2+ is bonded in a 12-coordinate geometry to twelve H1- atoms. There are a spread of La–H bond distances ranging from 2.31–2.88 Å. There are two inequivalent Ni1+ sites. In the first Ni1+ site, Ni1+ is bonded to four H1- atoms to form NiH4 tetrahedra that share corners with three equivalent MgH6 pentagonal pyramids. There is one shorter (1.57 Å) and three longer (1.58 Å) Ni–H bond length. In the second Ni1+ site, Ni1+ is bonded to four H1- atoms to form NiH4 tetrahedra that share corners with three equivalent MgH6 pentagonal pyramids. There are a spread of Ni–H bond distances ranging from 1.56–1.60 Å. There are fourteen inequivalent H1- sites. In the first H1- site, H1- is bonded in a 2-coordinate geometry to one Mg2+, two La2+, and one Ni1+ atom. In the second H1- site, H1- is bonded in a 2-coordinate geometry to one Mg2+, two equivalent La2+, and one Ni1+ atom. In the third H1- site, H1- is bonded to two Mg2+, one La2+, and one Ni1+ atom to form distorted corner-sharing HLaMg2Ni trigonal pyramids. In the fourth H1- site, H1- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg2+, one La2+, and one Ni1+ atom. In the fifth H1- site, H1- is bonded in a 1-coordinate geometry to two equivalent Mg2+, two La2+, and one Ni1+ atom. In the sixth H1- site, H1- is bonded in a 2-coordinate geometry to one Mg2+, two equivalent La2+, and one Ni1+ atom. In the seventh H1- site, H1- is bonded to two Mg2+, one La2+, and one Ni1+ atom to form distorted corner-sharing HLaMg2Ni trigonal pyramids. In the eighth H1- site, H1- is bonded in a 3-coordinate geometry to two equivalent Mg2+, one La2+, and one Ni1+ atom. In the ninth H1- site, H1- is bonded in a distorted water-like geometry to two Mg2+ and two equivalent La2+ atoms. In the tenth H1- site, H1- is bonded to two Mg2+ and two La2+ atoms to form distorted HLa2Mg2 tetrahedra that share corners with two equivalent HLa2Mg2 tetrahedra and corners with four HLaMg2Ni trigonal pyramids. In the eleventh H1- site, H1- is bonded in a distorted water-like geometry to two Mg2+ and two equivalent La2+ atoms. In the twelfth H1- site, H1- is bonded to two Mg2+ and two La2+ atoms to form HLa2Mg2 tetrahedra that share corners with two equivalent HLa2Mg2 tetrahedra and corners with four HLaMg2Ni trigonal pyramids. In the thirteenth H1- site, H1- is bonded in a distorted trigonal planar geometry to one Mg2+ and two La2+ atoms. In the fourteenth H1- site, H1- is bonded in a distorted trigonal planar geometry to one Mg2+ and two La2+ atoms.