Uncovering the hidden reactivity of benzyne/aryne precursors utilized under milder condition: Bonding and stability studies by EDA-NOCV analyses.

Arenes [C 6 H 3 R(TMS)(OTf); also called benzyne/aryne precursors] containing inter-related leaving groups Me 3 Si (TMS) and CF 3 SO 3 (OTf) on the adjacent positions (1,2-position) are generally converted to their corresponding aryne-intermediates via the addition of fluoride anion (F - ) and subsequent elimination of TMS and OTf groups. This reaction is believed to proceed via the formation of an anionic intermediate [C 6 H 4 (TMS-F)(OTf)] - . The EDA-NOCV analysis (EDA-NOCV = energy decomposition analysis-natural orbital for chemical valence) of over 35 such precursors of varied types have been reported to reveal bonding and stability of C Ar Si and COTf bonds. EDA-NOCV showed that the nature of the C Ar Si bond of C 6 H 3 R(TMS)(OTf) can be expressed as both dative and electron sharing [C Ar Si, C Ar →Si]. The C Ar OTf bond, on the other hand, can be described explicitly as dative [C Ar ←OTf]. The nature of C Ar Si bond of [C 6 H 4 (TMS-F)(OTf)] - exclusively changes to covalent dative σ-bond C Ar →S(Me)3F on the attachment of F - to the TMS group of C 6 H 4 (TMS)(OTf). Introduction of σ-electron withdrawing group (like OMe, NMe 2 , and NO 2 ) to the ortho-position of the TMS group of functionalized arynes C 6 H 3 R(TMS)(OTf) prefer to have a covalent dative σ-bond (C Ar →Si) over an electron-sharing covalent σ-bond (C Ar Si). If this σ-electron withdrawing group is shifted from ortho-position to meta- and para-positions, then the preference for a dative bond decreases significantly, implying that the electronic effect on the nature of chemical bonds affects through bond paths. This effect dies with distance, similar to the well-known inductive effect.