CRYSTAL-STRUCTURE AND PHASE-TRANSITIONS IN BETA-NH3(CH2)(2)NH3HPO4

Chemical preparation and main crystallographic, calorimetric, dielectric and structural features are given for a new monophosphate. beta-NH3(CH2)(2)NH3HPO4 salt is monoclinic P2(1)/c with unit cell dimensions a=10.189(2); b=7.881(1); c=8.021(1) Angstrom; beta=92.11(1)degrees; Z=4; D-m=1.604 Mg m(-3); D-x=1.632 Mg m(-3); mu=1.945 mm(-1); F(000)=336; T=298 K; R=0.044 and R(W)=0.047 for 1773 observed reflexions. The examination of the structure shows a layer arrangement: planes of HPO42- alternate with planes of [(CH2)(2)(NH3)(2)](2+). These planes are linked together through hydrogen bonds. Physical measurements carried our at high temperature show clearly that the beta variety presents calorimetric and dielectric behaviours different from those observed for the alpha variety.