Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

Abstract

The binding behavior of the bifunctional Lewis acid (η 5 -C 5 H 5 Fe) 2 [µ-(C 5 H 3 (BPh)) 2 ] (3) toward different pyridine derivatives as the Lewis base has been investigated. The 1:1 and 1:2 adducts, 3 • D and 3 • D 2 (donor, D ) 4-tert-butylpyridine (tBupy) and 4-dimethylaminopyridine (DMAP)), were obtained by lowtemperature crystallization or slow solvent evaporation techniques. The complexes were fully characterized by multinuclear NMR, IR, and elemental analysis. Single-crystal X-ray diffraction data were collected for the 1:1 adduct with DMAP and for both 1:2 adducts, and the marked structural changes upon pyridine binding are discussed in detail. In solution, the 1:2 adducts were found to readily undergo dissociation with formation of the 1:1 adducts as the dominant species at room temperature. Variable-temperature NMR and UV-visible titration studies demonstrate that the first binding process is more than 5 orders of magnitude more favorable than the second binding process.

9,10‐Dihydro‐9,10‐diboraanthracene: Supramolecular Structure and Use as a Building Block for Luminescent Conjugated Polymers

“…In contrast to this behavior, coordination of pyridine to 2 clearly shows negative binding cooperativity ( 2 +pyridine→ 2 ⋅pyridine: Δ G 298 =−13.3 kcal mol −1 ; 2 ⋅pyridine+pyridine→ 3 : Δ G 298 =−9.0 kcal mol −1 , see the Supporting Information. Experiments have shown qualitatively the same situation to occur for pyridine binding to the bifunctional Lewis acid B,B′‐diphenyldiboradiferrocene30).…”

Synthesis and supramolecular assembly of the bifunctional borinic acid [1,2-fcB(OH)]2

“…1 Among the most common boron heterocycles are borole (A) 2 and diborabenzene (B), 3 as well as their benzannulated congeners, the borafluorene (C) 4 and diboraanthracene (D) 5 derivatives. We have investigated in detail the corresponding redox-active ferrocene-fused diborabenzene systems E. [6][7][8][9][10] We have developed several synthetic routes to compounds of this type, using 1,1′-distannylated and 1,2-dimercurated ferrocene precursors. 8,10 An especially noteworthy property of compounds E is the strong electronic coupling between the ferrocene moieties across the electron-deficient diboron bridge.…”

Self-assembly of a tripyrenylboron molecule towards solid sensor for fluoride anions

“…In addition, triarylboron molecules with a large aryl substituent will easily interact with small Lewis base anions but repel larger and less Lewis basic anions. [39][40][41][42] The important structural feature of TPB is that the central B atom is connected with three pyrene molecules by B-C bonds. To verify whether this triarylboron compound maintains Lewis acidity and coordinates with a Lewis base, absorption and fluorescence spectra were studied.…”

“…3). 20 Because of an ion exchange interaction and a coordination equilibrium, [40][41][42] the new emission band at 450 nm disappeared gradually when more than 50 eq. of n-Bu 4 NF were added, meanwhile the blue-fluorescence was almost completely quenched (Fig.…”