Synthesis and Characterization of Ca 2 (PO 2 NH) 4 ·8H 2 O

Ca 2 (PO 2 NH) 4 · 8H 2 O was obtained as single‐phase crystalline powder starting from aqueous solution of K 4 (PO 2 NH) 4 · 4H 2 O and Ca(NO 3 ) 2 · 4H 2 O. A small fiber‐like specimen has been used for single‐crystal X‐ray structure determination. In the structure of Ca 2 (PO 2 NH) 4 · 8H 2 O ( Pbcn (no. 60), a = 1700.6(3), b = 1069.3(2), c = 963.2(2) pm, Z = 4) there are (PO 2 NH) 4 4– ions in saddle conformation which are interconnected by N–H ··· O hydrogen bonds forming infinite columns running along [001]. These columns are hold together by a complex hydrogen bonding network with crystal water molecules involved. The FTIR spectrum of the title compound has been measured and the relevant bands were assigned. 31 P solid‐state NMR investigations yielded three resolved resonances with chemical shift values of –3.1, –4.9 and –7.9 ppm. DTA / TG data are also discussed.