Phosphorus oxonitridosodalites: Synthesis using a molecular precursor and structural investigation by X-ray and neutron powder diffraction and 31P MAS NMR spectroscopy

Abstract

The oxonitridophosphates M(8-m)H(m)[P12N18O6]Cl2 (M = Cu, Li) with a sodalite-like [P12N18O6]6- framework of corner-sharing PN3O tetrahedra have been synthesized by the reaction of the respective metal chlorides with (NH2)2P(O)NP(NH2)3·NH4Cl. In this precursor the desired molar ratio, P:O=2:1, of the [P12N18O6]6- framework structure has been preorganized on a molecular level. Analogous oxonitridosodalites have also been obtained from the metal salts MX (M = Cu, Li; X = Cl, Br, I) or Li2S, the P/O and P/N components OP(NH2)3 and SP(NH2)3 or HPN2, and NH4X or MX as halogen sources. The crystal structures of the phosphorus oxonitridosodalites Cu4.8H3.2[P12N18O6]Cl2 (1), Li5.5H2.5[P12- N18O6]Cl2 (2), Li6.2H1.8[P12N18O6]Br2 (3), and Li5.8H2.2[P12N18O6]I2 (4) have been investigated by using neutron and X-ray powder diffraction as well as 31P MAS NMR spectroscopy. Rietveld refinements have been performed in the space group I43m (Z=1, a=820.25(1) to 830.81(2) pm for X = Cl to I). No experimental evidence for a crystallographic ordering of the N/O atoms and for other than PN3O tetrahedra in the sodalite frameworks has been obtained.