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The reaction of 2,2-dimethylpropane-1,3-diamine (dmpn) with an excess of concentrated aqueous hydrochloric acid yielded colorless crystals of 2,2-dimethylpropane-1,3-diaminium dichloride, dmpnH2Cl2 (1), in addition to small amounts of a monohydrate, dmpnH2Cl2∙H2O (2). The compounds were studied via X-ray crystallography, IR and Raman spectroscopy, NMR spectroscopy and thermal analysis. Single crystal structure determinations on 1 and 2 showed that dmpnH2Cl2 exists in two polymorphic forms, 1a and 1b. The crystal structure of 1b showed to be much more complex than that of 1a. In the crystal structure of 2, four (dmpnH2)2+ cations and eight chloride anions form a cage constructed by N−H∙∙∙Cl hydrogen bonds. In the center of these cages water dimers with a O∙∙∙O distance of 2.776 (8) Å are present. In addition, a conformational analysis of the 2,2-dimethylpropane-1,3-diaminium cation was performed. The results are compared to the experimental findings of 1a, 1b, 2 and other related hydrogen bonded salt structures from the Cambridge crystallographic structure database (CCDC). Last, a topological classification of the solid-state structures of 1a and 2 was performed and the simplified topological networks are discussed. [ABSTRACT FROM AUTHOR]

The reaction of ytterbium metal with ammonium trifluoroacetate in liquid ammonia resulted in a green substance comprising a substantial amount of ytterbium(II) trifluoroacetate that is a useful precursor for the oxidative synthesis of the new ytterbium(III) compound, [(NH4)1-x(H3O)x]2[Yb6F8-(O2CCF3)12(H2O)4].4H2O (x = 1/4), in aqueous trifluoroacetic acid. This mixed ammonium/oxonium crystalline solid is the first example of a substance containing an octahedro-hexanuclear ytterbium(III) complex with μ3-facecapping fluorido ligands. The main structural features of its [Yb6F8] core are non-bonding Yb...Yb distances and Yb--F bond lengths of 3.7576 (3)-3.9413 (5) and 2.2375 (17)-2.3509 (17) Å, respectively. Yb--O bond lengths involving the O atoms of O,O0-bridging carboxylato ligands and vertexsubstituting aqua ligands are in the ranges 2.23 (4)-2.329 (2) and 2.448 (2)-2.544 (3) Å, respectively. These bond lengths are in accordance with expectations, taking into account lanthanoid contraction. Interestingly, there is a significant ammonium versus oxonium ion site dependence, not only of the hydrate water molecule positions within the solid's hydrogen-bonding framework, but also of the coordination sites of one carboxylato and one aqua ligand in the hexanuclear complex. [ABSTRACT FROM AUTHOR]