The 1,2,3,5-ditelluradiazolyl [HCN₂Te₂] species. Theoretical characterizations of the cation, radical, and radical dimers

Abstract

Dithia-and diselena-diazolyl radicals (HCN,E, E = S, Se) and dimers are important building blocks in the design of low-dimensional molecular conductors. Research on the tellurium-based analogues is much rarer. This work reports the molecular and electronic structures of the cation, radical, and radical dimers of 1,2,3,5-ditelluradiazolyl using ab initio theory including electron correlation by Moller-Plesset perturbation theory up to partial fourth order (MP4SDQ). A face-to-face C2v dimer is predicted to be bound with respect to two radicals by approximately 18 kcallmol. A C,, dimer also has been studied and is ca. 2 kcaVmol less stable than the C,, conformer. Relaxing symmetry constraints on the dimers led to more energetically stable structures at the Hartree-Fock level but the C2" structure remains the most stable at a level of theory including electron correlation effects. The results for the Te compounds along with our earlier research on the S and Se analogues provide predictions for the geometries, vibrational frequencies, and ionization potentials for the Te species to assist in future experiments.Key words: tellurium, ab initio, ditelluradiazolyl, dimers, binding.RCsurnC : Les radicaux dithia-et disCltnadiazolyles (HCN2E2, E = S, Se) et leurs dimkres sont des blocs de construction importants dans le dCveloppement de conducteurs moltculaires de faibles dimensions. Des recherches sur des analogues ayant le tellure comme base sont beaucoup plus rares. Dans ce travail, on a calculC les structures moleculaires et electroniques du cation, du radical et des radicaux dimkres du 1,2,3,5-ditelluradiazolyle en utilisant la theorie ab initio, y compris la corrClation d'tlectrons par la thiorie des perturbations de Moiler-Plesser jusqu'au quatrikme ordre partiel (MP4SDQ). I1 est prCvu qu'un dimkre face B face C2v sera lie par environ I8 kcaVmol par rapport aux deux radicaux. On a aussi CtudiC un dimkre C2, et il est moins stable que le conformkre C2, par environ 2 kcallmol. Au niveau de Hartree-Fock, des contraintes de symttrie de relaxation appliquees aux dimkres ont conduit B des structures CnergCtiquement plus stables, mais la structure C2v demeure la plus stable B un niveau de la thCorie qui inclut les effets de correlation d'klectrons. Les rCsultats pour les composCs du Te en relation avec nos Ctudes antkrieures sur les analogues du S et du Se conduisent B des predictions au sujet des gComCtries, aux frCquences vibrationnelles et aux potentiels d'ionisation des espkces du Te qui pourront aider dans des experiences futures.

Synthesis, antimicrobial activity, computational and modeling studies of some new organotellurium compounds containing azo moities

“…In addition, the bands at the region 1635-1622cm -1 were assigned to the C=C aromatic group. In the 1 H NMR spectra of synthesized compounds, the hydroxy protons of 8-hydroxy quinoline were resonated as singlets at the regions δ 9.51-9.38 ppm and these values are in agreement with previously reported data [32]. The multiplet at the regions δ 7.22-9.11 ppm were attributed to the aromatic protons.…”

Synthesis and structure of N-arylimines of β-tellurocyclohexenals with the intramolecular coordination N→Te bonds

“….N bonds of the hypervalent type in the compounds 11 was evaluated as the energy difference (DE) between the ring-closed s-cis-and ring-opened strans-isomers of the compounds 18 differing from 11 by only the absence of one or two methyl groups in the N-aryl substituent. Results of the calculations performed with the use of density functional theory B3LYP/LanL2DZ level of approximation successfully employed in a number of previous theoretical studies of organotellurium compounds [37,38] are depicted in Fig. 8 and are given in Table 8 where comparison is also made between computationally predicted and X-ray determined structural parameters for the proper pairs of the compounds 18 and 11.…”

Density Functional Study of Tetra-Atomic Clusters and Complexes of the Group 16 Elements: Trends in Structure and Bonding

“…These X 2 molecules may be considered as the conceptual building blocks for the X 4 clusters which have been observed spectroscopically. 1a-d These tetra-atomic compounds are known to be less stable than larger clusters of the chalcogens, but Se 4 rings are incorporated into infinite chains of amorphous selenium 1e and exist in selenium gas. The use of selenium in the xerographic process has stimulated research on small selenium clusters. 1e,h Dithio-, diselena-, and ditelluradiazolyl dimers contain S 4 , Se 4 , and Te 4 fragments and are important building blocks in the design of low-dimensional molecular conductors. 1f, …”