A neutron structure analysis of tetragonal NH4(H2PO4)

The structure of tetragonal NH4H2PO 4 has been determined in a single-crystal neutron-diffraction study.The N-If • • • O and O-H • • • O bond systems suggested in earlier X-ray investigations were confirmed.The H2PO [ network is very similar to that found in KH2PO 4 ; the only significant difference observed was in the angle between the P-O and O-i • • • O bonds.The ammonium ion was found to be only slightly distorted from a regular tetrahedral arrangement.Considerable distortion would be necessary for linear N-i • • • O bonds.The observed angle between the Eli bond and the line joining nitrogen and oxygen centers was about 14 °.In order to achieve good agreement between calculated and observed data it was necessary to introduce anisotropic thermal vibration parameters.The final value of the discrepancy factor was 8.9 %.