Tuning Molecular Electron Affinities against Atomic Electronegativities by Spatial Expansion of a π‐System

Abstract

2,1,3‐Benzochalcogenadiazoles C6R4N2E (E/R; E=S, Se, Te; R=H, F, Cl, Br, I) and C6H2R2N2E (E/R’; E=S, Se, Te; R=Br, I) are 10π‐electron hetarenes. By CV/EPR measurements, DFT calculations, and QTAIM and ELI‐D analyses, it is shown that their molecular electron affinities (EAs) increase with decreasing Allen electronegativities and electron affinities of the E and non‐hydrogen R (except Cl) atoms. DFT calculations for E/R+e⋅−→[E/R]⋅− electron capture reveal negative ΔG values numerically increasing with increasing atomic numbers of the E and R atoms; positive ΔS has a minor influence. It is suggested that the EA increase is caused by more effective charge/spin delocalization in the radical anions of heavier derivatives due to contributions from diffuse (a real‐space expanded) p‐AOs of the heavier E and R atoms; and that this counterintuitive effect might be of the general character.

Halide Complexes of 5,6‐Dicyano‐2,1,3‐Benzoselenadiazole with 1 : 4 Stoichiometry: Cooperativity between Chalcogen and Hydrogen Bonding

“…The MEPs of 1 and 2 reveal typical of 1,2,5‐chalcogenadiazoles two equivalent σ‐holes at the Se atoms. The value of the MEP maximum at the σ‐hole, V S,max , for 1 and 2 is significantly larger than for the archetypal compound 3 ; [101,102] and for 1 V S,max is ~2 kcal mol −1 larger than for 2 . Besides, 1 and 2 possess π‐holes at both 6‐ and 5‐membered rings (and the holes at the 5‐membered rings are slightly deeper), which are absent in 3 .…”

“…Similar to Se…N catemeric 3 [100,113,114] and its TCNQ-fused derivatives [87,115] and N-bonded BR 3 complexes, [82] XRD crystal structure of 1 (Figure 3; SI) does not feature [Se…N] 2 supramolecular dimers observed for many 1,2,5selenadiazoles [51,82,86,91,101,102,116,119] (XRD structure of 2 was not solved due to twinning of available crystals). The [E…N] 2 (E = S, Se, Te) ChBs are attractive and their total bond strength is greater than either ChB individually; and neither a pair of CN substituents in 1,2,5-chalcogenadiazole ring (cf.…”

1,2,3,4‐Tetrafluorobiphenylene: A Prototype Janus‐Headed Scaffold for Ambipolar Materials

“…An attempt of a similar detection of the [2] *À radical anion (RA) in the temperature range À 10/À 30 °C at the electrolysis potential of À 1.9 V (Figure 3, Table 2) resulted in the EPR spectrum of an unidentified species (SI). [44] A high instability of RAs of fluorinated aromatics (e. g. C 6 F 6 , 1 and 4) [11,45,46] under normal conditions is typical, and is expected for antiaromatics such as 2.…”

Coordination Polymers between 3,4-Dicyano-1,2,5-telluradiazole and N,N,N′,N′-Tetramethylethane-1,2-diamine: The Decisive Role of Chalcogen Bonding

“…19−29 Normally, the complexation is accompanied by the charge-transfer band in UV/vis spectra, which can be used for optical (Vis or/and FL) recognition and sensing of LBs in solution. 19,30,31 In the case of 1, the complexes have been isolated in the form of cocrystals with neutral and charged LBs encompassing pyridine 21 /pyridine N-oxides, 27 diazabicyclo[2.2.2]octane (Dabco), 20 dimethyl sulfoxide, 16,28 crown ethers (Cr), 29 and N-heterocyclic carbenes, 26 as well as various anions. 19,21,23−25 With Dabco, coordination polymer [1•Dabco] ∞ was yielded.…”

“…In polar organic solutions containing neutral or charged N-, O-, and C-centered Lewis bases (LBs), compound 1 and many other 1,2,5-chalcogenadiazoles possessing polymeric crystal structures , depolymerize due to ChB -driven complexation, encompassing LB solvents as well. − Normally, the complexation is accompanied by the charge-transfer band in UV/vis spectra, which can be used for optical (Vis or/and FL) recognition and sensing of LBs in solution. ,, …”