Alexandre Carneiro Silvino

Synthesis and properties of bis(1,3-dithiole-2-thione-4,5-dithiolato)bismuthate(1-) salts, [Q][Bi(dmit)2]. Crystal structure of [AsPh4][Bi(dmit)2]·1/2DMSO: comparison of the solid state structures of [Q][Bi(dmit)2] and [Q][Sb(dmit)2]

Abstract Ionic complexes, [Q][Bi(dmit)2] (5:QNEt4, NBu4, 1,4-Me2-pyridinium and AsPh4), have been obtained from BiBr3 and [Q]2[Zn(dmit)2] [H2–dmit4,5-dimercapto-1,3-dithiole-2-thione]. As established by the crystal structure determination of [(5:QAsPh4)·1/2DMSO], the cations have near tetrahedral geometries and are well separated from the anions. The anions, containing chelating dmit ligands, are linked into chains via Bi–thiolato–S inter-anion bonds: Bi2S2 rings are formed within the chains, with Bi⋯Bi distances alternating between 3.7760(3) and 3.9092(3) A. The bismuth atoms are six-coordinate, arising from two inter-anion Bi–S [Bi–S=3.0391(13) and 3.1643(14) A] and four intra-anion Bi–S bonds [between 2.6680(13) and 2.8370(13) A], with stereochemistries, including the equatorial-sited stereochemically active lone pair, of distorted pentagonal bipyramids. There are no S⋯S contacts between the anions less than the sum of the van der Waals radii. Comparisons are made between the structure of [(5:QAsPh4)·1/2DMSO] and those reported previously for (5:QNEt4), [(5:QNEt4)·1/2Et2O] and [(5:QNBu4) as well as those for [Q][Sb(dmit)2] (4).

Crystal structures of three [bis(1,3-dithiole-2-thione-4,5-dithiolato)zincate]2− salts: [Q]2[Zn(dmit)2] (Q=1,4-Me2-pyridinium or NEt4) and [PPh4]2[Zn(dmit)2]·DMSO. Comparison of the dianion packing arrangements in [Q]2[Zn(dmit)2]

Abstract [Zn(dmit)2]2− dianions in [Q]2[Zn(dmit)2] complexes (2: Q=1,4-Me2-pyridinium (C7H10N) or NEt4), and [PPh4]2[Zn(dmit)2]·DMSO ((2: Q=PPh4)·DMSO) have distorted tetrahedral geometries, as a result of the 94.49(3) to 95.27(3)° range of the bite angle of the dmit ligands; H2-dmit=4,5-dimercapto-1,3-dithiole-2-thione, H2C3S5. The Zn–S bond lengths are in the range from 2.3285(8) to 2.3520(9) A. In (2: Q=C7H10N) and (2: Q=NEt4), both the cations and the dianions are found in alternating layers, which form columns and sheets. Whereas in (2: Q=C7H10N), there are no S⋯S contacts less than the sum of the van der Waals radii, 3.70 A, S⋯S contacts at 3.5792(13) and 3.6605(12) A, within dianion layers, are found in (2: Q=NEt4). In ((2: Q=PPh4)·DMSO), the steric bulk of the [PPh4]+ cations is such that the dianions cannot be distributed in well-defined sheets: no S⋯S contacts less than 4.0 A are found in ((2: Q=PPh4)·DMSO). The structures are compared with those reported for other [Q]2[Zn(dmit)2] compounds.

Bis(1,3-dithiole-2-one-4,5-dithiolato)antimonate(1-) salts, [Q][Sb(dmio)2]. Structural comparisons of [Q][Sb(dmio)2] and bis(1,3-dithiole-2-thione-4,5-dithiolato)antimonate(1-) salts, [Q][Sb(dmit)2]

Abstract Bis(1,3-dithiole-2-one-4,5-dithiolato)antimonate(1-) salts, [Q][Sb(C3OS4)2], [Q][Sb(dmio)2] (3: Q=NEt4, 1,4-dimethylpyridinium (DMP), PPh4 or ferrocenyl-CH2NMe3) and bis(1,3-dithiole-2-thione-4,5-dithiolato)antimonate(1-) salts, [Q][Sb(C3S5)2], [Q][Sb(dmit)2] (1: Q=AsPh4 or NBu4) have been obtained from SbBr3–NaSCN and [Q]2[Zn(dmio)2]or [Q]2[Zn(dmit)2]. The crystal structures of (1: Q=AsPh4 or NBu4) and (3: Q=NEt4 and DMP) have been determined. In all cases, the Sb centres are 6-coordinated and, with the inclusion of the lone pair, are considered to have pseudo pentagonal bipyramidal structures. The interanion interactions in these and related complexes are compared.

Crystal structure of tetrabutylammonium [bis(1,3-dithiole-2-thione-4,5-dithiolato)bismuthate(1-)], [NBu4][Bi(dmit)2]

Abstract The crystal structure of ionic [NBu4][Bi(dmit)2] (5: Q=NBu4), obtained from BiBr3 and [NBu4]2[Zn(dmit)2], has been determined. The bismuth atoms are six coordinate, as a consequence of two inter-anion Bi–S contacts with two neighbouring anions. In addition to the four intra-anion Bi—S bonds to the two thiolato S atoms of the dmit ligands [Bi–S between 2.5872(14) and 2.8082(13) A: the inter-anion bonds involve thione S atoms [Bi—S(10)i=3.2548(11) and Bi–S(10)ii 3.4628(13) A]. Excluding consideration of any lone pair effect, the Bi atoms have very distorted octahedral geometries. The anions form centrosymmetric pairs of chains with the shortest Bi–Bi distance of 4.180 A being between the pairs of chains; overlapping parallel dmit ligands, within the pairs of chains, are separated by a perpendicular distance of 3.477(2) A, with the dmit centroid–dmit centroid separation of 3.529 A, ideal for π–π interaction.

Bis(tetra-n-butylammonium) (a redetermination at 150 K) and bis(tetraphenylarsonium) bis(1,3-dithiole-2-thione-4,5-dithiolato)zinc(II) (at 300 K)

The title compounds are salts of the general form (Q(+))(2)[Zn(dmit)(2)](2-), where dmit corresponds to the ligand (C(3)S(5))(-) present in both and Q(+) to the counter-cations ((n)Bu(4)N)(+) [or C(16)H(36)N(+)] and (Ph(4)As)(+) [or C(24)H(20)As(+)], respectively. In the first case, Zn is in the 4e special positions of space group C2/c and hence the [Zn(dmit)(2)](2-) dianion possesses twofold axial crystallographic symmetry. Including these, there are now 11 known examples of [Zn(dmit)(2)](2-) or its analogues, with O replacing the exocyclic thione S, and [Zn(dmio)(2)](2-) dianions in nine structures with various Q. Comparison of these reveals a remarkable variation in details of the conformation which the dianion may adopt in terms of Zn coordination, equivalence of the Zn-S bond lengths, displacement of Zn from the plane of the ligand and overall dianion shape.

Crystal structure of 1,2-bis­[(2-tert-butyl­phen­yl)imino]­ethane

The whole molecule of the title compound, C22H28N2, (I), is generated by inversion symmetry. The molecule is rather similar to that of 2,3-bis[(2-tert-butylphenyl)imino]butane, (II), a diimine ligand comprising similar structural features [Ferreira et al. (2006 ▸). Acta Cryst. E62, o4282–o4284]. Both ligands crystallize with the –N=C(R)—C(R)=N– group around an inversion centre, in a trans configuration. Comparing the two structures, it may be noted that the independent planar groups in both molecules [the central link, –N=C(R)—C(R)=N–, and the terminal aromatic ring] subtend an angle of 69.6 (1)° in (II) and 49.4 (2)° in (I). Ferreira and co-workers proposed that such angle deviation may be ascribed to the presence of two non-classical intramolecular hydrogen bonds and steric factors. In fact, in (I), similar non-classical hydrogen bonds are observed, and the larger angular deviation in (II) may be assigned to the presence of methyl groups in the diimino fragment, which can cause steric hindrance due to the presence of bulky tert-butyl substituents in the aromatic rings. The C=N bond lengths are similar in both compounds and agree with comonly accepted values.