Abstract
Deuterated potassium orthophosphate hepta-hydrate, K3PO4·7D2O, crystallizes in the Sohnke space group P21, and its absolute structure was determined from 2017 Friedel pairs [Flack parameter 0.004 (16)]. Each of the three crystallographically unique K+ cations is surrounded by six water mol-ecules and one oxygen atom from the orthophosphate group, using a threshold for K-O bonds of 3.10 Å. The highly irregular coordination polyhedra are linked by corner- and edge-sharing into a three-dimensional network that is consolidated by an intricate network of O-D⋯O hydrogen bonds of medium strength.