A neutron diffraction determination of the structure of deuterated aluminium nitrate nonahydrate, A1(NO3)3.9D2O

Mr=393.26, monoclinic, P2 1/ c, a=13.8937 (14), b=9.6258 (7), c=10.9127 (7) Aring, beta=95.66 (1)deg, V=1452.3 (2) Aring 3, T=295K [the cell parameters were determined from the refinement of 39 theta values from a Guinier-Hagg X-ray powder film (Cr Kalpha radiation, lambda=2.28975 Aring, using a CoP 3 standard: a=7.70778 Aring)], Z=4, Dx=1.80 Mg m -3, final Rw( F2)=0.069 for all 4480 independent reflections collected out to sintheta/lambda=0.69 Aring -1. The crystal structure of Al(NO 3) 3.9D 2O has been studied by three-dimensional neutron diffraction data collected at 295K. The asymmetric unit contains Al(D 2O) 63+ octahedra, NO 3- ions and three D 2O molecules which are not coordinated to Al 3+ ions. All nine water molecules in the formula unit are crystallographically independent and the 19 hydrogen bonds donated have O...O distances in the range 2.650 (2)-3.054 (2) Aring. The hydrogen bonds donated by the D 2O molecules which are coordinated to Al 3+ ions are shorter than the other hydrogen bonds. A distinct correlation exists between the O-D and D...O distances.