Topotactic lithium exchange in manganese(III)arsenate hydrate: a switchable Jahn–Teller distorted framework

Abstract

The topotactic lithium exchange reaction of MnAsO4·H20 with LiNO3 at 200 °C to give LiMnAsO4(OH) is accompanied by a drastic change in the framework geometry, resulting from an unusual switch in the Jahn–Teller distortion of the MnIIIO6 octahedra from having four short Mn–O(As) and two long Mn–OH2 bonds to having two short and two long Mn–O(As) bonds plus two intermediate Mn–OH bonds in the lithium derivative, suggesting that frameworks containing Jahn–Teller ions might have potential as flexible host materials.