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The spin-lattice relaxation times of 1H and 35Cl as well as the 35Cl NQR frequencies in α-NH4HgCl3 are reported. The proton T1 data are explained in terms of C3 reorientation and S4 flip of NH4+ ions. The latter mode is also largely responsible for the 35Cl quadrupole relaxation rate. A marked change in the proton T1 at 55 K indicates a phase transition, ascribable to the ordering of the NH4+ ions.

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The crystal structure of tin(II) chloride dihydrate, SnCl2·2H2O has been redetermined by a single crystal X-ray diffractometer technique. The crystal is monoclinic, space group P21⁄c with a=9.313, b=7.250, c=8.970 Å, β=114°55′ and Z=4. The structure was solved by three-dimensional Patterson and electron density syntheses. An anisotropic least-squares refinement, based on 1695 independent reflections gave an R value of 0.04. The tin(II) atom forms a pyramidal complex with two chlorine atoms and one oxygen atom; the bond lengths in the pyramid are Sn–O, 2.33 and Sn–Cl, 2.50 and 2.56 Å and the bond angles are 86.9, 85.0, and 87.9°. These results support a view that the bonding in dichloroaquotin(II) complex is considerably ionic in character. This crystal consists of double layers of the aquocomplex, SnCl2·(OH2), parallel to (100) with intervening layers of the second water molecules. Both kinds of the water molecules are linked together by hydrogen bonds of 2.74, 2.79, and 2.80 Å into two-dimensional networks. The structure reported previously was found to be in error, although its essential feature was quite similar to the present one.