Crystal structure of sitagliptin dihydrogen phosphate monohydrate, C16H16F6N5O(H2PO4)(H2O)

Abstract

The crystal structure of sitagliptin dihydrogen phosphate monohydrate (sometimes referred to as sitagliptin phosphate monohydrate) has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Sitagliptin dihydrogen phosphate monohydrate crystallizes in space group P212121 (#19) with a = 6.137 108(12), b = 9.304 018(14), c = 38.307 67(10) Å, V = 2187.359(8) Å3, and Z = 4. The sitagliptin cation folds so that the two planar portions are roughly parallel. The ammonium group of the sitagliptin cation, the phosphate anion, and the water molecule form a network of strong hydrogen bonds. The result is a two-dimensional network, parallel to the ab plane. Halfway between these hydrogen bond planes, there are planes of high fluorine density. The powder pattern is included in the Powder Diffraction File™ as entry 00-064-1500.