A PACKING OF MONOMERIC AND DIMERIC Rh(III) COMPLEXES IN THE CRYSTAL STRUCTURES OF [Rh(H2O)6]F3.4H2O è [N(CH3)4][Rh2Cl9] G.V.Romanenko, N.V.Podberezskaya Institute of Inorganic Chemistry, Sib. Branch, Novosibirsk, Russia
The crystal structures of two novel Rh(III) compounds - [Rh(H2O)6]F3[[dotaccent]]4H2O (I) è [N(CH3)4][Rh2Cl9] (II), containing halogen ions, have been determined. In these compounds, a radically different functional role of the F- and Cl- ions is due to their size and a composition of outer-sphere components. The octahedral environment of Rh in I is provided by six H2O molecules which have displaced the F- ions into the outer sphere involving the additional four H2O. In II, the Rh-octahedra, formed by the Cl--ions, are combined into dimers via a common face. The packing of the [Rh(H2O)6]3+ ions formed pseudohexagonal layers with Rh-Rh distances equal to [010], 1/2[110] è 1/2[1 -1 0] in the trigon loops of the layer in structure I. The one-layer stacking explains a strong quasiperiodicity (c/2) in this structure. In vacancies of the trigon loops there are F- ions; the common faces of triangular prisms, formed by complex cations, are occupied by F- ions and outer-sphere H2O molecules.
In II , Rh atoms of dimeric anions (on the z>0, 0.35, 0.5 and 0.85 levels) in combination with C atoms of the cations (situated on the axes 3) form regular hexagonal nets of the 1/3a[[radical]]3 dimension. The one-layer packing (with a pseudoperiod c/4) is formed without regard for atomic sorts.
Crystal data (SYNTEX P21, [[lambda]]MoKo, [[theta]]/2[[theta]]-scan) for I: a=11.910(2), b=6.877(1), c=13.590(3) Å, [[beta]]=90.00(3)deg., V=1113.1(3) Å3, space group C2/c, Z=4, dcalc=2.029 g.cm-1, R=0.0257, 919 Fhkl; for II: a=9.083(1), c=20.705(4) , V=1479.3(4) Å3, space group P31c, Z=2, dcalc=1.714 g[[dotaccent]]cm-1, R=0.0737, 612 Fhkl.