The influence of (O, N)-deuteration on the crystal and molecular structure, thermal stability and spectroscopic properties of 1,3-propanediammonium hydrogenphosphate monohydrate

Exchange of mobile hydrogen atoms in 1,3-propanediammonium hydrogenphosphat e for deuterium (OH-->OD, NH-->ND) affects the thermal stability of the sal t. Additionally, (O,N)-deuteration induces some unexpected changes in the - CH2- vibrations in the IR spectrum of this compound. The structure of the t itle compound has been determined by single crystal X-ray diffraction analy sis at 290 K (protonated as well as deuterated crystals) and at 25 K (deute rated crystal). In all cases, the crystals are monoclinic, space group, P2( 1)/c. For C3H12N22+. HPO42-. H2O at 290 K (I) a = 7.0030(3), b = 16.7611(7) , c = 7.8417(4) Angstrom, beta = 113.766(4)degrees, V= 842.34(7) Angstrom(3 ); for C3H6D6N22+. DP O-4(2-). D2O at 290 K (II) a = 7.008(1), b = 16.786(3 ), c = 7.861(1) Angstrom, beta = 113.77(1)degrees V= 846.3(2) Angstrom(3); and at 25 K (III) a = 6.938(3), b = 16.634(9), c = 7.893(3) Angstrom, beta = 113.81(5)degrees V = 833.4(7) Angstrom(3). The 1,3-propanediammonium dica tion has the extended all-trans conformation. The structure contains a thre e-dimensional network of hydrogen bonds, in which all available proton dono rs are engaged. The phosphate groups are linked through relatively strong H bonds to form infinite chains along c. The water molecule is closely assoc iated with these chains by donating H bonds to two consecutive phosphate un its along the chain.