Structures of the chain metaphosphates NaM(PO 3 ) 3 (M = Ca or Sr)

Solid‐state 23 Na and 31 P magic‐angle spinning nuclear magnetic resonance spectroscopy and X‐ray crystallography have been used to study the structures of the chain metaphosphates NaCa(PO 3 ) 3 and NaSr(PO 3 ) 3 . The compounds are isostructural and crystallise in space group P −1 with the following parameters: NaCa(PO 3 ) 3 , a = 6.711 Å, b = 6.934 Å, c = 7.619 Å, α = 83.44° , β = 81.41° , γ = 82.80° ; NaSr(PO 3 ) 3 a = 6.805 Å, b = 7.133 Å, c = 7.720 Å and α = 83.71° , β = 80.48° , γ = 82.87° . Both structures contain anionic metaphosphate chains of (PO 3 ) n n with ionic contacts to Na + ions in distorted octahedral sites and Ca 2+ (or Sr 2+ ) in distorted dodecahedral sites. 31 P and 23 Na NMR are entirely consistent with the crystallographic data and an empirical method for assigning 31 P resonances to particular crystallographically unique P atoms is described. Copyright © 2008 John Wiley & Sons, Ltd.