Formation of indium(III) 1,3-dithiole-2-thione-4,5-dithiolate anions, [In(dmit)2]1− and [In(dmit)]3−. Crystal structure of Cs[In(dmit)2]: Strong cation–anion interactions

•Controlled formations of InIII(dmit)2]− salts.•Controlled formations of InIII(dmit)3]−3 salts.•Crystal structure of [Cs][InIII(dmit)2].•Cation–anion interactions in [Cs][InIII(dmit)2].•Comparison of the crystal structures of [Cs][InIII(dmit)2] and [NBu4][InIII(dmit)2].

The preparations of [InIII(dmit)n]m− (m,n = 1,2 or 3,3) salts, using [Na]2[dmit] and [Cs]2[dmit] as dmit sources, are reported ([dmit]2− = 1,3-dithiole-2-thione-4,5-dithiolate). Characterizations were generally achieved via elemental analyses and IR spectroscopy. Compounds, [Q][InIII (dmit)2] (Q = NMe4, PPh4 and AsPh4) were generally obtained using mole ratios of [Na]2[dmit]:QX (X = halide):InCl3 of 2:1:1. However, using [Cs]2[dmit] with the same addition sequence of reagents and a similar mole ratio of reagents, mixed cation salts, [Q]y[Cs]1−y[In(dmit)2] (e.g., Q, y = NBu4, 0.323; PPh4, 0.437), were isolated. Tris(dmit) salts, [InIII(dmit)3]3−, were invariably obtained using reagent mole ratios of [Cs]2[dmit]:[Q]X:InCl3 = 3:3:1 in MeOH solution. However only with the bulkiest cations, (Q+ = [AsPh4]+ or [PPh4]+), were single salts, [Q]3[In(dmit)3], obtained. For less bulky cations, such as (Q+ = [NBu4]+ or [NMe4]+), compounds isolated had mixed cations, [Q]x[Cs]3−x[InIII(dmit)3].The crystal structure of [Cs][InIII(dmit)2] was determined from data collected at 120 K. Primary coordination to indium is through the thiolato sulfurs of two chelating dmit ligands, which provides four equal bonds of length 2.4678(7) Å, in a distorted tetrahedral array. Strong cation–anion interactions are present, providing four Cs–S bonds of length 3.6433(3) and four of length 3.6828(7) Å to thione and thiolato sulfurs, respectively, and a three dimensional array. Thus caesium is eight coordinate in [Cs][InIII(dmit)2].

Graphical abstractThe preparations of [InIII(dmit)n]m− (m,n = 1,2 or 3,3) salts, using [Na]2[dmit] and [Cs]2[dmit] as dmit sources, are reported ([dmit]2− = 1,3-dithiole-2-thione-4,5-dithiolate).Figure optionsDownload full-size imageDownload as PowerPoint slide