Sladjana B. Novaković

Electronic features and hydrogen bonding capacity of the sulfur acceptor in thioureido-based compounds. Experimental charge density study of 4-methyl-3-thiosemicarbazide

Sulfur atom is generally considered as a weak hydrogen bonding acceptor which is mostly explained by its low electronegativity. This is a background, and motivation, for this study that aims to provide additional insight into electronic features of the sulfur acceptor. The analysis of sulfurs electronic features uses high-resolution, low-temperature X-ray diffraction datasets on 4-methyl-3-thiosemicarbazide (MeTSC) and salicylaldehyde thiosemicarbazone (SalTSC). The total electron density distribution was modeled using Hansen–Coppens multipole model. The fact that MeTSC crystallizes with two crystallographically independent (but chemically equivalent) molecules, engaging in partly different D–H⋯S interactions, has, quite conveniently, enabled the examination of fine effects of the D–H⋯S interactions on the lone pairs electron density of the two S acceptors. The deformation density distribution, topological analysis of the total experimental charge density ρ(r) and its Laplacian (∇2ρ(r)), and, finally, electrostatic potential all point to the great flexibility of the S acceptor and its ability to adjust to the spatial distribution of the interacting donor groups. Toroidal accumulation of the S lone pairs electron density, strong value of the negative electrostatic potential even at a distance of 3.1 A from the S nucleus, and interpenetration of the van der Waals spheres for the donor and S acceptor atoms are all an indication of sulfurs capacity to simultaneously engage in a greater number of interactions than conventional acceptors such as O and N.

Different intermolecular interactions in azido[2-(diphenylphosphino)benzaldehyde semicarbazonato-kappa2P,N1,O]nickel(II).

The title compound, [Ni(C(20)H(17)N(3)OP)(N(3))], is the first complex with a semicarbazide-based ligand having a P atom as one of the donors. The influence of the P atom on the deformation of the coordination geometry of the Ni(II) ion is evident but less expressed than in the cases of complexes with analogous seleno- and thiosemicarbazide ligands. The torsion angles involving the two bonds formed by the P atom within the six-membered chelate ring have the largest values [C-P-Ni-N = 24.3 (2) degrees and C-C-P-Ni = -24.2 (4) degrees ], suggesting that the P atom considerably influences the conformation of the ring. Two types of N-H...N hydrogen bond connect the complex units into chains.

Rigid ferrocene–ferrocene dimer as a common building block in the crystal structures of ferrocene derivatives

The CSD study shows that 46.8% of ferrocene (Fc) containing crystal structures form a ferrocene–ferrocene dimer (FcD). In all those 2120 structures the FcD exhibits very similar geometry. An outstanding electrostatic complementarity between the Fc units within the dimer explains very frequent formation and constrained geometry of this building block.

1-Ferrocenyl-3-(4-methyl­anilino)propan-1-one

In the title ferrocene derivative, [Fe(C5H5)(C15H16NO)], the dihedral angle between the best planes of the benzene and the substituted cyclopentadienyl ring is 83.4 (1)°. The presence of a methyl substituent in the para position of the aniline group does not alter the crystal packing compared to that of 3-anilino-1-ferrocenylpropan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m229]. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

3-Anilino-1-ferrocenylpropan-1-one

In the title ferrocene derivative, [Fe(C5H5)(C14H14NO)], the dihedral angle between the mean planes of the phenyl ring and the substituted cyclopentadienyl ring is 84.4 (1)°. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

A new polymorph of 1-ferrocenyl-3-(3-nitroanilino)propan-1-one.

Recrystallization of the title compound, [Fe(C(5)H(5))(C(14)H(13)N(2)O(3))], from a mixture of n-hexane and dichloromethane gave the new polymorph, denoted (I), which crystallizes in the same space group (P1) as the previously reported structure, denoted (II). The Fe-C distances in (I) range from 2.015 (3) to 2.048 (2) Å and the average value of the C-C bond lengths in the two cyclopentadienyl (Cp) rings is 1.403 (13) Å. As indicated by the smallest C-Cg1-Cg2-C torsion angle of 1.4° (Cg1 and Cg2 are the centroids of the two Cp rings), the orientation of the Cp rings in (I) is more eclipsed than in the case of (II), for which the value was 15.3°. Despite the pronounced conformational similarity between (I) and (II), the formation of self-complementary N-H···O hydrogen-bonded dimers represents the only structural motif common to the two polymorphs. In the extended structure, molecules of (I) utilize C-H···O hydrogen bonds and, unlike (II), an extensive set of intermolecular C-H···π interactions. Fingerprint plots based on Hirshfeld surfaces are used to compare the packing of the two polymorphs.

Crystal structure of tetra­aqua­(5,5′-dimethyl-2,2′-bipyridyl-κ2N,N′)iron(II) sulfate

In the crystal structure of the title compound, [Fe(dmbpy)(H2O)4][SO4], the charged components form an extensive hydrogen-bonding network. Eight O—H⋯O hydrogen bonds [d(O⋯H) < 2.00 Å], form a two-dimensional network parallel to the ab plane.

1-Ferrocenyl-3-(3-fluoro-anilino)propan-1-one.

The title ferrocene derivative, [Fe(C5H5)(C14H13FNO)], crystallizes in the same space group with similar unit-cell parameters as the derivatives 3-anilino-1-ferrocenylpropan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m229] and 1-ferrocenyl-3-(4-methylanilino)propan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m230]. The dihedral angle between the best planes of the benzene ring and the substituted cyclopentadienyl ring is 83.4 (1)°. The presence of the electronegative fluoro substituent in the meta position of the aniline group does not alter the crystal packing compared to the other two derivatives. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

Transition metal complexes with ­thiosemicarbazide‐based ligands. XLIII.

In the title compound, [ZnCl(C(2)H(7)N(3)S)(2)]Cl, the Zn(II) ion is five-coordinated in a distorted trigonal-bipyramidal arrangement, with the hydrazine N atoms located in the apical positions. The structure is stabilized by N[bond]H...Cl hydrogen bonds, which involve both the Cl atoms and all the hydrogen donors, except for one of the two thioamide N atoms. A comparison of the geometry of thiosemicarbazide and S-methylisothiosemicarbazide complexes with Zn(II), Cu(II) and Ni(II) shows the pronounced influence of the hydrogen-bond network on the coordination geometry of Zn(II) compounds.

(E)-4-[(2-Carbamoylhydrazinylidene)methyl]-3-hydroxy-5-hydroxymethyl-2-methylpyridin-1-ium nitrate

The title compound, C9H13N4O3(+)·NO3(-), is the first structurally characterized Schiff base derived from semicarbazide and pyridoxal. Unusually for an unsubstituted semicarbazone, the compound adopts a syn conformation, in which the carbonyl O atom is in a cis disposition relative to the azomethine N atom. This arrangement is supported by a pair of hydrogen bonds between the organic cation and the nitrate anion. The cation is essentially planar, with only a hydroxymethyl O atom deviating significantly from the mean plane of the remaining atoms (r.m.s. deviation of the remaining non-H atoms = 0.01 Å). The molecules are linked into flat layers by N-H···O and C-H···O hydrogen bonds. O-H···O hydrogen bonds involving the hydroxymethyl group as a donor interconnect the layers into a three-dimensional structure.