TY - JOUR

T1 - New Charge-Transfer Complexes with 1,2,5-Thiadiazoles as Both Electron Acceptors and Donors Featuring an Unprecedented Addition Reaction

AU - Chulanova, Elena A.

AU - Pritchina, Elena A.

AU - Malaspina, Lorraine A.

AU - Grabowsky, Simon

AU - Mostaghimi, Farzin

AU - Beckmann, Jens

AU - Bagryanskaya, Irina Yu

AU - Shakhova, Margarita V.

AU - Konstantinova, Lidia S.

AU - Rakitin, Oleg A.

AU - Gritsan, Nina P.

AU - Zibarev, Andrey V.

N1 - Publisher Copyright: © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

PY - 2017/1/18

Y1 - 2017/1/18

N2 - The design and synthesis of novel charge-transfer (CT) complexes are of interest for fundamental chemistry and applications to materials science. In addition to the recently described first CT complex with both electron acceptor (A) and donor (D) groups belonging to the 1,2,5-thiadiazole series (1; A: 4-nitro-2,1,3-benzothiadiazole; D: 4-amino-2,1,3-benzothiadiazole), herein novel CT complexes 2 and 3 with 1,2,5-thiadiazoles as both A (4,6-dinitro-2,1,3-benzothiadiazole and [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole) and D (4-amino-2,1,3-benzothiadiazole) were synthesized. The series is completed by complex 4 with [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole as A and phenoxatellurine as D. Structures of complexes 2–4 were characterized by single-crystal X-ray diffraction (XRD), as well as solution and solid-state UV/Vis spectroscopy. Thermodynamics of their formation were obtained by density functional theory (DFT) calculations, their bonding situations were analyzed by quantum theory of atoms in molecules (QTAIM) calculations and dimer model energies of interactions quantified in the framework of the Hirshfeld surface (HS) analysis. With DFT calculations, the largest value of CT between D and A was found for complex 2, with 0.027 e in the XRD structure and 0.150 e in the optimized structure in MeCN. In the UV/Vis spectra, the λmax of the CT bands of 2–4 varied in the range λ=517–705 nm. Model energy calculations for 1–4 revealed the importance of both dispersion interactions and hydrogen bonding between D and A as contributors to CT in the crystalline state. In an attempt to enlarge the CT value with bis[1,2,5-thiadiazolo][3,4-b;3′,4′-e]pyrazine as A and 4-amino-2,1,3-benzoselenadiazole as D, an unprecedented 1:1 addition reaction was observed upon formation of a C−N bond between atom C7 of D and pyrazine atom N4 of A, accompanied by hydrogen atom transfer from C7 to another pyrazine atom N8 (compound 5). According to DFT calculations, the reaction is a multistep process featuring diradical intermediates and hydrogen atom intramolecular migration over four positions. Molecular and crystal structures of 5 (solvate with toluene) were elucidated by XRD and the crystal structure revealed a rather unusual porous framework.

AB - The design and synthesis of novel charge-transfer (CT) complexes are of interest for fundamental chemistry and applications to materials science. In addition to the recently described first CT complex with both electron acceptor (A) and donor (D) groups belonging to the 1,2,5-thiadiazole series (1; A: 4-nitro-2,1,3-benzothiadiazole; D: 4-amino-2,1,3-benzothiadiazole), herein novel CT complexes 2 and 3 with 1,2,5-thiadiazoles as both A (4,6-dinitro-2,1,3-benzothiadiazole and [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole) and D (4-amino-2,1,3-benzothiadiazole) were synthesized. The series is completed by complex 4 with [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole as A and phenoxatellurine as D. Structures of complexes 2–4 were characterized by single-crystal X-ray diffraction (XRD), as well as solution and solid-state UV/Vis spectroscopy. Thermodynamics of their formation were obtained by density functional theory (DFT) calculations, their bonding situations were analyzed by quantum theory of atoms in molecules (QTAIM) calculations and dimer model energies of interactions quantified in the framework of the Hirshfeld surface (HS) analysis. With DFT calculations, the largest value of CT between D and A was found for complex 2, with 0.027 e in the XRD structure and 0.150 e in the optimized structure in MeCN. In the UV/Vis spectra, the λmax of the CT bands of 2–4 varied in the range λ=517–705 nm. Model energy calculations for 1–4 revealed the importance of both dispersion interactions and hydrogen bonding between D and A as contributors to CT in the crystalline state. In an attempt to enlarge the CT value with bis[1,2,5-thiadiazolo][3,4-b;3′,4′-e]pyrazine as A and 4-amino-2,1,3-benzoselenadiazole as D, an unprecedented 1:1 addition reaction was observed upon formation of a C−N bond between atom C7 of D and pyrazine atom N4 of A, accompanied by hydrogen atom transfer from C7 to another pyrazine atom N8 (compound 5). According to DFT calculations, the reaction is a multistep process featuring diradical intermediates and hydrogen atom intramolecular migration over four positions. Molecular and crystal structures of 5 (solvate with toluene) were elucidated by XRD and the crystal structure revealed a rather unusual porous framework.

KW - chalcogens

KW - charge transfer

KW - donor–acceptor systems

KW - quantum chemistry

KW - X-ray diffraction

KW - HETEROSPIN S-1

KW - ORGANIC SOLAR-CELLS

KW - X-RAY-STRUCTURE

KW - CRYSTAL-STRUCTURES

KW - EXCITED-STATES

KW - donor-acceptor systems

KW - BASIS-SETS

KW - DENSITY-FUNCTIONAL THEORY

KW - 1,2,5-CHALCOGENADIAZOLE DERIVATIVES

KW - RADICAL-ANION

KW - EXPLORING INTERMOLECULAR INTERACTIONS

UR - http://www.scopus.com/inward/record.url?scp=85006710509&partnerID=8YFLogxK

U2 - 10.1002/chem.201604121

DO - 10.1002/chem.201604121

M3 - Article

C2 - 27958639

AN - SCOPUS:85006710509

VL - 23

SP - 852

EP - 864

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 4

ER -