Bismuth⋯π arene versus bismuth⋯halide coordination in heterocyclic diorganobismuth(iii) compounds with transannular N→Bi interaction

Abstract

New diorganobismuth(iii) bromides of type [RN(CHCH)]BiBr [R = CHCH (1), CHCHCH (2), and CHOCHCH (3)], based on the heterocyclic butterfly-like tetrahydro-dibenzo[c,f][1,5]azabismocine framework, were prepared starting from the corresponding RN(CHCHBr-2) in a succession of reactions including ortho-lithiation and treatment of the dilithio derivative with BiBr in a 1 : 1 molar ratio. Further exchange reactions between bromides and appropriate metal halides or ammonium fluoride resulted in the formation of [RN(CHCH)]BiX [X = Cl and I for R = CHCH (4 and 5) and CHCHCH (6 and 7) and X = F (8), Cl (9), and I (10) for R = CHOCHCH]. All ten compounds were structurally characterized in solution by NMR and in the solid state by single-crystal X-ray diffraction. Strong transannular N→Bi interactions were observed in all the investigated diorganobismuth(iii) halides, thus giving rise to hypervalent 10-Bi-4 species in 1, 2, 4-7 and 12-Bi-5 species in 3, 8-10, where the oxygen atom in the pendant arm is intramolecularly coordinated to bismuth. The molecules are associated in dimeric units by strong Biπ arene interactions in 3, 4, and 10 (approx. 3.50 Å) and by BiX interactions in 1, 5, and 7. Bromide 1, chloride 4, and iodide 5 are isostructural, but stronger polarization of the Bi-Cl bond favors Biπ arene interaction in 4 over Bihalide interactions, as observed in 1 and 5. In the isostructural series [RN(CHCH)]BiX (R = CHOCHCH), Bioxygen interactions compensate the electron deficiency at bismuth in fluoride 8 and chloride 9, whereas the coordination sphere of bismuth is completed by a combination of Biπ arene and Bihalide interactions in bromide 3 and only by Biπ arene interactions in iodide 10. Moreover, weak Hπ arene and HX intermolecular interactions, mainly of dispersion type, contribute to supramolecular networks in all three series of compounds.

Hypercoordinated diorganoantimony(III) compounds of types [2‐(Me2NCH2)C6H4]2SbL and [PhCH2N(CH2C6H4)2]SbL (L = Cl, ONO2, OSO2CF3). Synthesis, structure and catalytic behaviour in the Henry reaction

“…In 3 and 4 the methylene and the methyl protons in the CH 2 NMe 2 moiety give broad singlet resonances at room temperature, thus suggesting a fast dynamic process in solution [3h, 32]. The non‐equivalent CH 2 N CH 2 protons in the fused diheterocyclic skeleton of 4 – 6 appear as an AB spin system in the 1 H NMR spectra, while the C H 2 protons in the PhCH 2 N moiety give a sharp singlet resonance, similar to the situation found for the diorganobismuth(III) analogues …”

“…[3h, 32] The non-equivalent CH 2 NCH 2 protons in the fused diheterocyclic skeleton of 4-6 appear as an AB spin system in the 1 H NMR spectra, while the CH 2 protons in the PhCH 2 N moiety give a sharp singlet resonance, similar to the situation found for the diorganobismuth(III) analogues. [33] Compounds 2 and 5 show in their IR spectra strong, broad bands at 1458/1285 cm −1 and 1495/1270 cm −1 , respectively, which might suggest a chelating bidentate coordination of the anionic NO 3 − ligand. [34] The IR spectra of 3 and 6 show strong bands at 1292/1030 cm −1 and 1265/1030 cm −1 , respectively, which were assigned to the ν as (SO 2 ) and ν s (SO 2 ) vibrations of the triflate anion.…”

Homo‐ and Heteroleptic Coordination Polymers and Oxido Clusters of Bismuth(III) Vinylsulfonates

“…[56] This interaction can be assigned to the lower range of London dispersion type Bi···p(arene) interactions, as reported for other bismuth compounds. [57] For example, Bi···arene(centroid) distances in the range of 3.44-3.91 have been given for benzyl-, aryl-, and heteroarylbismuthanes, [58] whereas polymorphsofthe starting material BiPh 3 show Bi···Ph(centroid) distances that range from 3. 47 show similara rrangements as observed for 1.F or example, in the crystal structure of [{Ph 2 Bi(OTf)} n ], Bi···Ph(centroid) distances of 3.49 and angles y of 2.98 are found.…”

Heterocyclic bismuth(iii) compounds with transannular N→Bi interactions as catalysts for the oxidation of thiophenol to diphenyldisulfide

“…These different behaviors might be explained by the observation that in solid state the bismuth atom in 1 is involved in weak Bi The latter is present in both 1 and 2 and of a similar magnitude [2.531(4) Å in 1 and 2.532(13) Å in 2]. 47 Therefore, it is likely to be a significant difference in the accessibility of the active site for the organic substrates to bind. Furthermore, the activity of the diorganobismuth(III) compounds 3 -6 resulted in high conversions and TON.…”

“…46 We have recently reported diorganobismuth(III) halides of the type [RCH 2 N(CH 2 C 6 H 4 ) 2 ]BiX (R = C 6 H 5 , C 6 H 5 CH 2 , CH 3 OCH 2 , X = halogen). 47 As a continuation of our studies regarding the compounds based on a tetrahydrodibenzo[c,f][1,5]azabismocine heterocyclic framework we used the bromides RCH 2 N(CH 2 C 6 H 4 ) 2 ]BiBr [R = C 6 H 5 (1), C 6 H 5 CH 2 (2)] to prepare the new species [RCH 2 N(CH 2 C 6 H 4 ) 2 ]BiX [R = C 6 H 5 , X = ONO 2 (3), OSO 2 CF 3 (4), OSO 2 C 6 H 4 (CHCH 2 )-4 (5); R = C 6 H 5 CH 2 , X = ONO 2 (6)]. Compounds 1 -6 were investigated as catalysts in the oxidation with air of thiophenol to diphenyl disulfide in both cyclohexane and IL (1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide).…”