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The title compound, C 6 H 4 BrNS, crystallizes in the space group P 2 1 / n with one complete mol-ecule in the asymmetric unit. The non-H atoms are nearly planar (r.m.s for non-H atoms = 0.071 Å), with the nitrile group oriented anti-periplanar with respect to the thio-phene S atom. Inter-molecular Type I centrosymmetric Br⋯Br halogen inter-actions are present at a distance of 3.582 (1) Å and with a C-Br⋯Br angle of 140.7 (1)°. Additional weaker C-H⋯N, C-H⋯S, and S⋯π inter-actions are also present. A Hirshfeld analysis indicates Br⋯Br inter-actions comprise only 1.9% of all the inter-atomic contacts.

The synthesis and characterization of base-stabilized and base-free pincer-type bis(phosphine)/silylene [P 2 Si]Ru complexes are reported. The base-free complex readily reduces CO 2 and CS 2 via silylene-assisted hydride transfer, affording structurally distinct products with silicon-to-ruthenium formate and dithioformate bridges.

In the structures of the 2,6-bis-(1,2,4-triazoly-3-yl)methyl-substituted pyridine compound, C11H11N7, (I) and the iodide triiodide salt, C13H17N7 (2+)·I(-)·I3 (-), (II), the dihedral angles between the two triazole rings and the pyridine ring are 66.4 (1) and 74.6 (1)° in (I), and 68.4 (2)° in (II), in which the dication lies across a crystallographic mirror plane. The overall packing structure for (I) is two-dimensional with the layers lying parallel to the (001) plane. In (II), the triiodide anion lies within the mirror plane, occupying the space between the two triazole substituent groups and was found to have minor disorder [occupancy ratio 0.9761 (9):0.0239 (9)]. The overall packing of structure (II) can be described as two-dimensional with the layers stacking parallel to the (001) plane. In the crystal, the predominant inter-molecular inter-actions in (I) and (II) involve the acidic hydrogen atom in the third position of the triazole ring, with either the triazole N-atom acceptor in weak C-H⋯N hydrogen bonds in (I), or with halide counter-ions through C-H⋯I inter-actions, in (II).

The title compounds, C36H28OP2S2, (1), and C36H28OP2Se2, (2), exhibit remarkably similar structures although they are not isomorphous. The whole mol-ecule of compound (2) is generated by twofold symmetry, with the ether O atom located on the twofold axis. Both compounds have intra-molecular π-π inter-actions between terminal phenyl rings with centroid-centroid distances of 3.6214 (16) and 3.8027 (14) Å in (1) and (2), respectively. In the crystal of (1), short C-H⋯S hydrogen bonds link the mol-ecules, forming chains along [001], while in (2) there are no analogous C-H⋯Se inter-actions present.

The crystal structure of the title salt, C8H12N(+)·C4H3O4 (-), consists of a 2,5-di-methyl-anilinium cation and an hydrogen maleate anion. In the anion, a strong intra-molecular O-H⋯O hydrogen bond is observed, leading to an S(7) graph-set motif. In the crystal, the cations and anions pack in alternating layers parallel to (001). The ammonium group undergoes inter-molecular N-H⋯O hydrogen-bonding inter-actions with the O atoms of three different hydrogen maleate anions. This results in the formation of ribbons extending parallel to [010] with hydrogen-bonding motifs of the types R (4) 4(12) and R (4) 4(18).

The title compounds, [Mo(C5H5)(COCH3)P(CH3)2(C6H5)(CO)2], (1), and [Mo(C5H5)(COCH3)P(C2H5)(C6H5)2)(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. Both complex mol-ecules exhibit a four-legged piano-stool geometry with trans-disposed carbonyl ligands along with Mo-P bond lengths and C-Mo-P angles that reflect the relative steric pressure of the respective phosphine ligand. The structure of compound (1) exhibits a layered arrangement parallel to (100). Within the layers mol-ecules are linked into chains along [001] by non-classical C-H⋯O inter-actions between the acetyl ligand of one mol-ecule and the phenyl and methyl phosphine substituents of another. In the structure of complex (2), a chain motif of centrosymmetrical dimers is found along [010] through C-H⋯O inter-actions.

In the title compound, C13H10N2O4, the nitro groups are twisted significantly relative to the benzene rings [dihedral angles = 16.64 (18) and 28.02 (11)°]. The benzene groups are nearly perpendicular to each other [dihedral angle = 87.72 (6)°]. Short inter-molecular N⋯O and C⋯O [2.981 (2) and 3.060 (2) Å, respectively] contacts suggest possible weak π-inter-actions between nitro groups and between benzene and nitro groups. In addition, there are π-π inter-actions between one benzene group and an inversion-related equivalent [inter-planar separation = 3.494 (2) Å].

In the title complex, [Co(C6H15N2)Cl3], the Co(2+) ion is coordinated in a distorted tetra-hedral fashion by three chloride ions and one N atom of the piperazine ring; the ring adopts a chair conformation with the N-Co and N-CEt bonds in equatorial orientations. In the crystal, mol-ecules are connected by N-H⋯Cl hydrogen bonds, generating (10-1) sheets.

In the title mol-ecular salt, (C10H16N2)[CoCl4], the piperazine ring of the phenyl-piperazine dication adopts a chair conformation and the phenyl ring occupies an equatorial orientation. In the tetra-chlorido-cobaltate(II) dianion, the Co-Cl bond lengths for the chloride ions not accepting hydrogen bonds are significantly shorter than those for the chloride ions accepting such bonds. In the crystal, the components are linked by N-H⋯Cl hydrogen bonds, generating [001] chains.

The title compound, [Mo(C5H5)(C2H3O)(C12H9O3P)(CO)2], was prepared by reaction of [Mo(C5H5)(CO)3(CH3)] with tris-(furan-2-yl)phosphane. The Mo(II) atom exhibits a four-legged piano-stool coordination geometry with the acetyl and phosphine ligands trans to each other. The O atom of the acetyl ligand points down, away from the Cp ring. In the crystal, mol-ecules form centrosymmetrical dimers via π-π inter-actions between furyl rings [the centroid-centroid distance is 3.396 (4) Å]. The dimers are linked by C-H⋯O hydrogen bonds into layers parallel to (100).

The title compound, [Mo(C(5)H(5))(C(2)H(3)O)(C(13)H(13)P)(CO)(2)], was prepared by reaction of [Mo(CH(3))(C(5)H(5))(CO)(3)] with methyl-diphenyl-phosphane. The Mo(II) atom exhibits a four-legged piano-stool coordination geometry with the acetyl and phosphane ligands trans to each other. There are several inter-molecular C-H⋯O hydrogen-bonding inter-actions involving carbonyl and acetyl O atoms as acceptors. A close nearly parallel π-π inter-action between the cyclo-penta-dienyl plane and the phenyl ring of the phosphane ligand is present, with an angle of 6.4 (1)° between the two least-squares planes. The centroid-to-centroid distance between these groups is 3.772 (3) Å, and the closest distance between two atoms of these groups is 3.449 (4) Å. Since each Mo complex is engaged in two of these inter-actions, the complexes form an infinite π-stack coincident with the a axis.

In the title compound, (C(16)H(36)N)(2)[Pd(C(4)N(2)S(2))(2)], the Pd(II) center adopts a distorted square-planar geometry due to the four-membered chelate rings formed by coordination of the 2,2-dicyano-ethyl-ene-1,1-dithiol-ate (i-mnt) ligands [bite angle 75.0159 (17)°]. The bond distances in the coordinated i-mnt ligands indicate some delocalization of the π-system.

In the title compound, (C(16)H(36)N)(2)[Pt(C(4)N(2)S(2))(2)], the Pt(II) center adopts a distorted square-planar geometry due to the 4-membered chelate rings formed by coordination to the S atoms of the 1,1-dicyano-ethyl-ene-2,2-dithiol-ate (i-mnt) ligands [bite angle 74.35 (4)°]. The bond distances in the coordinated i-mnt ligands indicate some delocalization of the π-system.

A series of tricyanovinyl (TCV)-substituted oligothiophenes was synthesized and investigated with a number of physical methods including UV/Vis, IR, and Raman spectroscopy, nonlinear optical (NLO) measurements, X-ray diffraction, and cyclic voltammetry. Mono- or disubstituted oligomers were prepared by the reaction of tetracyanoethylene with mono- or dilithiated oligomers. The comparative effects of the symmetric and asymmetric substitutions in the electronic and molecular properties have been addressed. These oligomers display dramatic reductions in both their optical and electrochemical band gaps in comparison with unsubstituted molecules. The analysis of the electronic properties of the molecules was assisted by density functional theory calculations, which are in excellent agreement with the experimental data. TCV substitution influences the energies of the frontier orbitals, especially with respect to the stabilization of LUMO orbitals. X-ray structural characterization of a monosubstituted oligomer exhibits pi-stacking with favorable intermolecular interactions. NLO results agree with the role of the intramolecular charge-transfer feature in the asymmetric samples. These results furthermore exalt the role of conformational flexibility in the disubstituted compounds and reveal an unexpected nonlinear optical activity for symmetric molecules. Regarding the electronic structure, the interpretation of the vibrational data reflects the balanced interplay between aromatic and quinoid forms, finely tuned by the chain length and substitution pattern. The electronic and structural properties are consistent with the semiconducting properties exhibited by these materials in thin film transistors (TFTs).