Solvothermal syntheses, high- and low-temperature crystal structures, and thermochromic behavior of [1,2-diethyl-3,4,5-trimethyl-pyrazolium]4[Bi4I16] and [1,10-phenanthrolinium][BiI4]·(H2O)

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A new iron(II) scorpionate complex, {Fe[HC(3,4,5-Me3pz)3]2}(I)2 (pz = pyrazolyl) (1), and two novel compounds containing low-dimensional poly(iodobismuthate) anions [1,2-Et2-3,4,5-Me3pz]4[Bi4I16] ([1,2-Et2-3,4,5-Me3pz]+ = [1,2-diethyl-3,4,5-trimethyl-pyrazolium]+) (2), and [H(1,10-phen)][BiI4]·(H2O) ([H(1,10-phen)]+ = [1,10-phenanthrolinium]+) (3), have been synthesized and characterized by single crystal X-ray diffraction. Crystals of 2 resulted from the solvothermal reaction of BiI3 and {Fe[HC(3,4,5-Me3pz)3]2}(I)2 in an ethanol/water solvent mixture. The anion of this compound is discrete (0-D) and consists of four slightly distorted BiI6 octahedra joined in an edge-sharing arrangement, and the cation is a decomposition/solvent attack product of the iron scorpionate complex. Crystals of 3 resulted from the solvothermal reaction of BiI3, 1,10-phenanthroline, and CuI in an ethanol/water solvent mixture. [H(1,10-phen)][BiI4]·(H2O) contains 1-D chains of BiI6 octahedra and a protonated phenanthroline/water molecule complex. Both 2 and 3 are thermochromic compounds as their colors change, respectively, from orange at 296 K to yellow upon cooling to 100 K and from red-orange at 296 K to orange at 100 K. Crystallographic data at both temperatures were recorded for each sample and are reported here. The crystallographic data indicate that interatomic distances (Bi–I and Bi⋯Bi) within the inorganic anions change as a function of temperature, and it is believed that these changes are associated with the observation of thermochromism. {Fe[HC(3,4,5-Me3pz)3]2}(I)2 (1) crystallizes in the monoclinic space group P21/n with the following lattice parameters at 150(1) K: a = 10.8489(5) Å, b = 17.6642(9) Å, c = 15.4131(8) Å, β = 102.4860(10)°. [Et2Me3pz]4[Bi4I16] (2) and [H(1,10-phen)][BiI4]·(H2O) (3) both crystallize in the triclinic space group P1¯" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">P1¯ with the following lattice parameters for 2 at 296(1) K and 100(1) K, respectively: a = 11.2923(4) Å, b = 13.6412(5) Å, c = 15.0824(6) Å, α = 78.2090(10)°, β = 71.9670(10)°, and γ = 67.4020(10)°; a = 11.0963(7) Å, b = 13.4158(8) Å, c = 14.9840(9) Å, α = 79.1450(10)°, β = 71.1310(10)°, and γ = 68.1360(10)°. Lattice parameters for 3 at 296(1) K and 100(1) K, respectively, are as follows: a = 7.7590(4) Å, b = 11.1477(5) Å, c = 12.0731(6) Å, α = 77.6570(10)°, β = 79.1900(10)°, and γ = 71.2950(10)°; a = 7.7000(4) Å, b = 10.9265(6) Å, c = 11.9748(7) Å, α = 78.1020(10)°, β = 79.9940(10)°, and γ = 71.8380(10)°.