Exploring weak intermolecular interactions in thiocyanate-bonded Zn(ii) and Cd(ii) complexes with methylimidazole: crystal structures, Hirshfeld surface analysis and luminescence properties

We report the synthesis, spectroscopy and X-ray crystal structures of four Cd(ii) and Zn(ii) coordination compounds with imidazole derivatives and thiocyanate as co-ligands.

A detailed exploration of intermolecular interactions in 4-(4-dimethylaminobenzylideneamino)-N-(5-methyl-3-isoxazolyl)benzenesulfonamide and related Schiff bases: Crystal structure, spectral studies, DFT methods, Pixel energies and Hirshfeld surface analysis

The Schiff base of the title has been synthesized and its crystal structure determined by single-crystal X-ray diffraction. The compound was characterized by IR, Raman, ¹H NMR, ¹³C NMR and electronic absorption spectra. DFT calculations provide the quantum chemical basis for the observed molecular conformation. A study of intermolecular interactions of the title compound is compared with seven other closely related structures and reveals that molecules in most of the compounds are linked by a cooperative effect of strong and weak hydrogen bonds, CH^…π, and π^…π stacking interactions, and also lp^…π contacts. Lattice energy calculations indicate that the dispersion component is the major contribution, with the coulombic term playing a significant role in the total energy. Interaction energies for molecular pairs involving NH···N bonds indicate a dominant contribution to packing stabilization coming from coulomb component. Hirshfeld surfaces and 2D-fingerprint plots allowed us to visualize different intermolecular contacts and its relative contributions to total surface in each compound. The analysis of electrostatic potential (ESP) maps correlates well with the computed energies providing evidences on the dominant electrostatic nature of NH···N and NH···O interactions.

Gold(I) Hydrides as Proton Acceptors in Dihydrogen Bond Formation

Wavefunction and DFT calculations indicate that anionic dihydride complexes of Au^I form strong to moderate directed Au-H⋅⋅⋅H bonds with one or two HF, H₂ O and NH₃ prototype proton donor molecules. The largely electrostatic interaction is influenced by relativistic effects which, however, do not increase the binding energy. Very weak Au⋅⋅⋅H associations-exhibiting a corresponding bond path-occur between neutral AuH and HF units, although ultimately F becomes the preferred donor atom in the most stable structure. Increasing the hydridicity of AuH by attachment of an electron donating NHC ligand effects Au-H⋅⋅⋅H bonding of moderate strength only with HF, whereas competing Au⋅⋅⋅H interactions dominate for H₂ O and NH₃ . Rare η² coordinated and HX (X=F or OH) associated H₂ complexes are produced during interaction with a single ion of stronger acidity, H₂ F⁺ or H₃ O⁺ . Theoretically, reaction of excess [AuH₂ ]^- as proton acceptor with H₃ O⁺ or NH₄⁺ in 3:1 or 4:1 ionic ratios, respectively, affords H⋅⋅⋅H bonded analogues of Eigen-type adducts. Outstanding analytical relationships between selected bonding parameters support the integrity of the results.