POLYSELENIDE CHEMISTRY OF INDIUM AND THALLIUM IN DIMETHYLFORMAMIDE, ACETONITRILE, AND WATER - SYNTHESES, STRUCTURES, AND PROPERTIES OF THE NEW COMPLEXES [IN2(SE4)4(SE5)]4-, [IN2SE2(SE4)2]2-, [IN3SE3(SE4)3]3-, AND [TL3SE3(SE4)3]3-

The reaction of InCl3 with Na2Se5 in dimethylformamide (DMF) in the pr esence of Ph4PCl gave (Ph4P)46[In2(Se4)4(Se5)] (I) in 75% yield. Under the same conditions, InCl3 reacted with Na2Se5 in the presence of Pr4 NBr or Et4NBr and afforded (Pr4N)4[In2(Se4)4(Se5)] (II) in 65% yield a nd (Et4N)4[In2(Se4)4(Se5)] (III) in 72% yield, respectively. (I) cryst allizes in the triclinic space group P1BAR (No. 2) with unit cell dime nsions a = 11.417(4) angstrom, b = 12.734(9) angstrom, c = 20.188(9) a ngstrom, alpha = 96.03(5)-degrees, beta = 94.69(3)-degrees, gamma = 11 1.68(4)-degrees, V = 2689(2) angstrom3, Z = 1, and R/R(w) = 0.073/0.0 85. (II) crystallizes in the monoclinic space group P2/c (No. 13) with unit cell dimensions a = 15.997(3) angstrom, b = 15.781(3) angstrom, c = 17.540(4) 17.376(3) angstrom, c = 15.168(2) angstrom, beta = 94.56 (3)-degrees, V = 4202(1) angstrom3, Z = 2, and R/R(w) = 0.069/0.080. ( III) crystallizes in the triclinic space group P1BAR (No. 2) with unit cell dimensions a = 12.428(3) angstrom, b = 15.781(3) angstrom, c = 1 7.540(4) angstrom, alpha = 89.47(2)-degrees, beta = 97.90(2)-degrees, gamma = 94.47(2)-degrees, V = 3397(1) angstrom3, Z = 2, and R/R(w) = 0 .075/0.084. Single-crystal X-ray diffraction studies show that (I), (I I), and (III) contain the same anion, [In2(Se4)4(Se5)]4-. The anion co nsists of In3+ centers in trigonal bipyramidal coordination; each In a tom is chelated by two bidentate Se4(2-) ligands forming a [In(Se4)2]- unit. Two of these [In(Se4)2]- units are bridged by an Se5(2-) chain forming a dimer. The hydrothermal reaction of InCl3 with Na2Se4 in the presence of Pr4NBr and water at 110-degrees-C for 3 days in an evacua ted sealed Pyrex tube afforded deep red crystals of (Pr4N)2[In2Se2(Se4 )2] (IV), in 80% yield. Under the same conditions the reaction with [( Ph3P)2N]Cl yields [(Ph3P)2N]2[ln2Se2(Se4)2] (V) in 60% yield. (IV) cry stallizes in the triclinic space group P1BAR (No. 2) with unit cell di mensions a = 8.938(2) angstrom, b = 11.290(2)angstrom, c = 11.528(2) a ngstrom, alpha = 79.19(1)-degrees, beta = 105.56(l)-degrees, gamma = 9 9.84(l)-degrees, V = 1093(1) angstrom3, Z = 1, and R/R(w) = 0.045/0.04 9. (V) also crystallizes in the triclinic space group P1BAR (No. 2) wi th unit cell dimensions a = 10.931(5) angstrom, b = 11.302(7) angstrom , c = 15.189(s) angstrom, alpha = 84.98(5)-degrees, beta = 94.15(4)-de grees, gamma = 93.86(4)-degrees, V = 1858(1) angstrom3, Z = 1, and R/R (w) = 0.060/0.081. Single-crystal X-ray diffraction studies show that (IV) and (V) contain the same binuclear anion [In2Se2(Se4)2]2-. The an ion contains In3+ with a tetrahedral coordination, bridged by two mono selenides to form a planar [In2Se2]2+ core with an inversion center at the middle of the In--In vector of 3.336(2) angstrom. The remaining t wo coordination sites on each In atom are occupied by the Se4(2-) bide ntate chelates. The reaction of InCl3 with Na2Se5 in 1:2 mole ratio in acetonitrile in the presence of Et4NBr afforded (Et4N)3[In3Se3(Se4)3] (VI). Similar reaction of TlCl with Na2Se5 in 1:2 mole ratio in DMF i n the presence of Et4NBr gave (Et4N)3[Tl3Se3(Se4)3] (VIII). Single-cry stal X-ray diffraction studies show that the two compounds (VI) and (V II) are isostructural and crystallize in the monoclinic space group P2 (1)/c (No. 14). The unit cell dimensions are a = 16.747(4) angstrom, b = 13.701(3) angstrom, c = 22.227(3) angstrom, beta - 94. 16(2)-degree s, V = 5086(2) angstrom3, Z = 4, and R/R(w) = 0.045/0.051 and a = 16.8 13(3) angstrom, b = 13.774(3) angstrom, c = 22.186(4) angstrom, beta = 94.13(1)-degrees; V = 5126(2) angstrom3, Z = 4, and R/R(w) = 0.072/0. 087 for (VI) and (VII), respectively. The trinuclear anion [M3Se3(Se4) 3]3- (M = In, Tl) in (VI) and (VII) contains M3+ with a tetrahedral co ordination. Each M3+ center has a chelating Se4(2-) ligand and is brid ged to the other two M3+ centers by monoselenide, Se2-, ligands formin g a six-membered [M3Se3]3+ core. Variable-temperature Se-77 NMR spectr a of (I)-(VII) are reported. All indium-polyselenide complexes show th e same NMR spectrum at room temperature in DMF suggesting that in solu tion only one In/Se species exists. UV/vis of (I)-(III) are similar, w ith two absorptions at approximately 450 and approximately 650 nm, whi le (IV)-(VII) have a featureless spectra. The electrochemistry of (I) and (VI) is reported. The solid-state far-IR spectra of all the compou nds show strong absorptions in the 300-100 cm-1 region due to the Se-S e and M-Se stretching frequencies; tentative assignments are reported herein. Thermal gravimetric analysis data show that the compounds pyro lyze to give single-phase binary metal chalcogenides (beta-In2Se3 and TlSe).