Preparation and characterization of novel inorganic-organic hybrid materials containing rare, mixed-halide anions of bismuth(III)

Three new hybrid inorganic-organic salts containing novel mixed haloanions of bismuth were synthesized by the solvothermal reaction of bismuth iodide with a haloacid, HX (X = Cl or Br), and the alkylamine 4,4'-trimethylenedipiperidine (TMDP). All three compounds were structurally characterized by single-crystal X-ray diffraction. Reaction of TMDP and Bil(3) with HCl yielded two crystalline products: [H2TMDP](2)[(Bi(2)l(9))(BiCl(2)l(2))1 (1, major yield) and [H2TMDP](2)[Bi2Cl10-(chi)l(chi)] (2, x = 3.83, minor yield). Compound 1 crystallizes in the monoclinic space group Cc (a = 22.8586(l 1) Angstrom, b = 15.5878(7) A, c = 17.6793(g)Angstrom, beta = 118.7010(10)degrees, Z = 4) and contains the mononuclear mixed-halide anion BiCl(2)l(2)(-) in addition to a face-sharing bioctahedral Bi(2)l(9)(3)- anion and two independent H2TMDP2+ cations. The BiCl(2)l(2)(-) anion has a sawhorse geometry (equatorially vacant trigonal bipyramidal geometry) that is not commonly observed in bismuth chemistry. Compound 2 crystallizes in the monoclinic space group P2(1)/c (a = 14.9471(7) Angstrom, b = 12.7622(6) Angstrom, c = 13.3381(7) Angstrom, beta = 116.1030(10)degrees, Z = 2) and contains an edge-sharing bioctahedral mixed-halide anion in which iodide occupies one and chloride occupies two of the five crystallographically independent halide sites. The remaining two sites have mixed-chloride and -iodide occupancy. Reaction of TMDP and Bil(3) with HBr yielded the crystalline product [H2TMDP][BiBr(5-chi)l(chi)] (3, x = 0.99), which contains, in addition to the organic cation, a polymeric, mixed-haloanion of bismuth(III). Compound 3 crystallizes in the chiral, orthorhombic space group P2(1)2(1)2(1) (a = 8.5189(5) Angstrom, b = 14.8988(9) Angstrom, c = 17.9984(11) Angstrom, Z = 4) and consists of an H2- TMDP2+ cation in addition to the anion, which is built up of corner-sharing BiX6 octahedra. Of the five crystallographically independent halide sites in this anion, two are occupied solely by Br and the remaining three have mixed-bromide and -iodide occupancy. Other anion stoichiometries have been observed crystallographically for 3, as the specific stoichiometry is dependent on the relative concentration of the haloacid starting material used.