Oxidation-induced activation of chalcogen bonding in redox-active bis(selenomethyl)tetrathiafulvalene derivatives

Abstract

Chalcogen bonding (ChB) interactions are investigated in two new –SeMe substituted tetrathiafulvalene (TTF) derivatives, RTTF(SeMe)2 (R = Me2, SCH2CH2S). Upon oxidation to 1:1 cationic radical salts, Se atoms are engaged...

Chalcogen bonding and variable charge transfer degree in two polymorphs of 1 : 1 conducting salts with segregated stacks

“…Based on a formula developed in the literature, 14 the charge of F 2 TCNQ is estimated as ρ A = −1.12. For the donor side, we used the reported structures of EDT-TTF(SeMe) 2 in neutral and radical cation states 11 to derive an analogue formula. Regarding the asymmetry of the substituents on TTF, we considered only CC and C–S bond distances to establish a parameter δ D = e − d , then made a linear relationship using ρ D = ( δ − δ 0 )/( δ 1 − δ 0 ) as shown in Table 1.…”

“…In searching for potential TTF derivatives which can act as ChB donors, we have recently demonstrated strong σ-hole activation of selenium in EDT-TTF(SeMe) 2 (Scheme 1) upon their oxidation. 11 Here, the oxidation-induced Se activation in conjunction with geometrically well-disposed –SeMe functional groups led to efficient chalcogen bonding interactions with bromide anions in semiconducting 1 : 1 [EDT-TTF(SeMe) 2 ]Br salt. Considering the notably proficient ChB-donating ability of EDT-TTF(SeMe) 2 , we decided to investigate its incorporation within CT salts and the influence of ChB in their solid-state properties.…”

Selective Activation of Chalcogen Bonding: An Efficient Structuring Tool toward Crystal Engineering Strategies

“…Figure 3). 25,26 Finally, it should be stressed here that this dissymmetrization approach offers the advantage of being systematic and not strictly limited to ChB. It will indeed find applications with all other interactions where several σ-holes compete for a specific acceptor, as illustrated recently in pnictogen bonding, 65 or tetrel bonding.…”

“…These TTF derivatives have been also recently engaged in charge transfer salts with electron acceptors such as TCNQ or TCNQF 2 (TCNQ: tetracyanoquinodimethane), providing mixed-valence salts with metallic conductivity, stabilized by Se•••N≡C TCNQ ChB interactions. 26 We wanted to extend this dissymmetrization concept to neutral ChB donors and developed this approach along three main families respectively, selenocyanates R−SeCN, alkynyl derivatives R−C�C−(Se/Te)Me, and o-carborane derivatives B 10 H 10 [C−(Se/Te)Me] 2 , as gathered in Scheme 2.…”

Non-covalent interactions in neutral and oxidized tetrathiafulvalenes

“…12,13 More recently, chalcogen bonding (ChB) 14 have focused also attention in this research area. 15 An interesting characteristic of these non-covalent interactions is that when the hydrogen, halogen or chalcogen atoms are located on an electroactive moiety such as TTF, the lower electronic density called σ-hole, located on the extension of the covalent bond, 16 is enhanced upon oxidation. Indeed neutral TTF, substituted by a halogen or chalcogen atom, is an electron donor molecule, but once oxidized, the TTF exerts an electron withdrawing effect that increases the magnitude of the σ-hole and thus favor such intermolecular interactions.…”