A comparison between observed and DFT calculations on structure of 5-(4-chlorophenyl)-2-amino-1,3,4-thiadiazole

Abstract

The crystal and molecular structure of 5-(4-chlorophenyl)-2-amino-1,3,4-thiadiazole 3 was reported, which was characterized by various spectroscopic techniques (FT-IR, NMR and HRMS) and single-crystal X-ray diffraction. The crystal structure 3 (C8H6ClN3S) crystallized in the orthorhombic space group Pna21 and the unit cell consisted of 8 asymmetric molecules. The unit cell parameters were a = 11.2027(2) Å, b = 7.6705(2) Å, c = 21.2166(6) Å, α = β = γ = 90°, V = 1823.15(8) Å3, Z = 8. In addition, the structural geometry (bond lengths, bond angles, and torsion angles), the electronic properties of mono and dimeric forms of compound 3 were calculated by using the density functional theory (DFT) method at B3LYP level 6-31+ G(d,p), 6-31++ G(d,p) and 6-311+ G(d,p) basis sets in ground state. A good correlation was found (R2 = 0.998) between the observed and theoretical vibrational frequencies. Frontier molecular orbitals (HOMO and LUMO) and Molecular Electrostatic Potential map of the compound was produced by using the optimized structures. The NBO analysis was suggested that the molecular system contains N-H…N hydrogen bonding, strong conjugative interactions and the molecule become more polarized owing to the movement of π-electron cloud from donor to acceptor. The calculated structural and geometrical results were in good rational agreement with the experimental X-ray crystal structure data of 1,3,4-thiadiazol-2-amine, 3. The compound 3 exhibited n→π* UV absorption peak of UV cutoff edge, and great magnitude of the first-order hyperpolarizability was observed. The obtained results suggest that compound 3 could have potential application as NLO material. Therefore, this study provides valuable insight experimentally and theoretically, for designing new chemical entities to meet the demands of specific applications.

The Balance between Hydrogen Bonds, Halogen Bonds, and Chalcogen Bonds in the Crystal Structures of a Series of 1,3,4-Chalcogenadiazoles

“…All iodine-containing structures not undergoing halogen bonding show that despite the predictability of the MEPs, it was not always perfect; however, in general, the increased structural influence can be attributed to larger σ-hole potentials of the more polarizable iodine atom. The lack of halogen bonds in previously reported fluorine [38] and chlorine [39] analogs further validates the expectation that a more polarizable halogen atom is more likely to influence the solid-state assembly in ways to go beyond simple (and less directional) packing forces. A comparison of the frequency of occurrence of hydrogen, halogen, and chalcogen bonds in the crystal structures of these 1,3,4-chalcogendiazole shows that the former was the most prominent; hydrogen bonding exists in all of them and 4/5 exist as hydrogen bond dimers and 5/5 as single hydrogen bond formation.…”

“…With an improved insight into how chalcogen atoms form intermolecular interactions, we may be able to (i) deepen our understanding of the origins of photophysical behavior of chargetransfer complexes and (ii) develop more effective bottom-up syntheses for new classes of semi-conductors and other high-value molecular materials. Based on relevant structures in the CSD [36][37][38][39], as well as on preliminary hydrogenbond propensity calculations (Table S1, Scheme S1) [40], it was deemed likely that a dimer formation through a pair of identical hydrogen bonding (hydrogen-bond dimer) would be most prominent in this system. However, the tunability of the different interactions that can be produced within single component systems (Figure 2) can, in principle, lead to a range of different synthons and structural arrangements.…”

Solution and Solid-State Photophysical Properties of Positional Isomeric Acrylonitrile Derivatives with Core Pyridine and Phenyl Moieties: Experimental and DFT Studies

“…The NBO I – V were performed using the NBO program carried out through the GAUSSIAN software [ 64 ] at the DFT/B3LYP level. The natural bond orbital analysis is a method for studying intra- and intermolecular bonding and interactions among bonds, besides providing a convenient basis for investigating charge transfer or conjugative relations in molecular structure [ 92 , 93 , 94 , 95 , 96 ]. The greater stabilization energy E(2) value indicates more intensive interaction amongst the electron acceptors and donors, i.e., the higher electron donating ability and superior degree of conjugation of the whole system.…”

Synthesis, identification, density functional and Hirshfeld surface studies of 2,2′‐disulfanediylbis(tetrahydro‐4H‐cyclopenta[d][1,3,2]dioxaphosphole‐2‐sulfide)

“…Recently and according to the great progress in the supercomputers, quantum chemical methods become very useful tools in determining the molecular structures, electronic structure andreactivity of the molecules. The conceptual density functional theory (DFT) as one of the quantum chemical methods has been effectively used to compare the experimental data with the theoretical ones 25–27 …”