Weil Matthias, Veyer Théo
Institute for Chemical Technologies and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria.
IUT Bordeaux 1, 15 Rue Naudet, 33175 Gradignan, France.
Acta Crystallogr E Crystallogr Commun. 2019 Jun 7;75(Pt 7):969-971. doi: 10.1107/S2056989019008065. eCollection 2019 Jul 1.
A new form of NaMnAsO, sodium manganese(II) orthoarsenate, has been obtained under hydro-thermal conditions, and is referred to as the β-polymorph. In contrast to the previously reported ortho-rhom-bic α-polymorph that crystallizes in the olivine-type of structure and has one manganese(II) cation in a distorted octa-hedral coordination, the current β-polymorph contains two manganese(II) cations in [5]-coordination, inter-mediate between a square-pyramid and a trigonal bipyramid. In the crystal structure of β-NaMnAsO, four [MnO] polyhedra are linked through vertex- and edge-sharing into finite {MnO} units strung into rows parallel to [100]. These units are linked through two distinct orthoarsenate groups into a framework structure with channels propagating parallel to the manganese oxide rows. Both unique sodium cations are situated inside the channels and exhibit coordination numbers of six and seven. β-NaMnAsO is isotypic with one form of NaCoPO and with NaCuAsO.
一种新形式的砷酸锰钠（NaMnAsO，正砷酸锰(II)钠）已在水热条件下制得，被称为β多晶型物。与之前报道的以橄榄石型结构结晶且具有一个处于扭曲八面体配位的锰(II)阳离子的正交α多晶型物不同，当前的β多晶型物包含两个处于[5]配位的锰(II)阳离子，介于四方锥和三角双锥之间。在β-NaMnAsO的晶体结构中，四个[MnO]多面体通过顶点共享和棱共享连接成有限的{MnO}单元，这些单元串成平行于[100]的行。这些单元通过两个不同的正砷酸根基团连接成具有平行于氧化锰行传播的通道的骨架结构。两种独特的钠离子位于通道内部，配位数分别为六和七。β-NaMnAsO与一种形式的NaCoPO以及NaCuAsO是同型的。
