Facile Bismuth−Oxygen Bond Cleavage, C−H Activation, and Formation of a Monodentate Carbon-Bound Oxyaryl Dianion, (C₆H₂^tBu₂-3,5-O-4)²⁻

Abstract

The Bi(3+) (N,C,N)-pincer complex Ar'BiCl(2) (1) [Ar' = 2,6-(Me(2)NCH(2))(2)C(6)H(3)], reacts with 2 equiv of KOC(6)H(3)Me(2)-2,6 and KOC(6)H(3)(i)Pr(2)-2,6 by ionic metathesis to form the anticipated bis(aryloxide) complexes Ar'Bi(OC(6)H(3)Me(2)-2,6)(2) (2) and Ar'Bi(OC(6)H(3)(i)Pr(2)-2,6)(2) (3), respectively. However, the analogous reaction with 2 equiv of KOC(6)H(3)(t)Bu(2)-2,6 forms HOC(6)H(3)(t)Bu(2)-2,6 and a dark-orange complex containing only one aryloxide-derived ligand bound via a Bi-C and not a Bi-O linkage. This complex is formulated as Ar'Bi(C(6)H(2)(t)Bu(2)-3,5-O-4) (4), a product of para C-H bond activation. Structural, spectroscopic, and DFT studies and a comparison with the protonated analogue [Ar'Bi(C(6)H(2)(t)Bu(2)-3,5-OH-4)][BPh(4)] (5), which was obtained by treatment of 4 with [HNEt(3)][BPh(4)], suggest that 4 contains an oxyaryl dianion. Complex 4 represents a fully characterizable product of a bismuth-mediated C-H activation and rearrangement of the type postulated in catalytic SOHIO processes.

Double CH Activation of a Masked Cationic Bismuth Amide

“…[1][2][3][4] One CH activation of industrial relevance is the SOHIO process,i nw hich ah eterogeneous bismuth catalyst ("nMoO 3 /Bi 2 O 3 ") is used for the oxidation or ammoxidation of propene. [5,6] This has not only contributed to our mechanistic understanding of the SOHIO process,b ut has also revealed intriguing reactivity patterns.Examples include the formation of am onodentate oxy-aryl dianion in the coordination sphere of bismuth (Scheme 1b), its selective insertion reactions with CO 2 and NO,a nd its oxidative C À C coupling reactions. [5,6] This has not only contributed to our mechanistic understanding of the SOHIO process,b ut has also revealed intriguing reactivity patterns.Examples include the formation of am onodentate oxy-aryl dianion in the coordination sphere of bismuth (Scheme 1b), its selective insertion reactions with CO 2 and NO,a nd its oxidative C À C coupling reactions.…”

Oxidation of Tertiary Aromatic Alcohols to Ketones in Water

“…To our delight, heterocycles like 2-(thiophen-2-yl)propan-2-ol (13) and 2-(pyridin-2-yl)propan-2-ol (14) were also oxidized smoothly, leading to the desired 1-(thiophen-2-yl) ethan-1-one and 1-(pyridin-2-yl)ethan-1-one respectively in moderate yields. Notably, neither C-phenyl bond cleavage nor C-methyl bond cleavage was observed (17)(18)(19)(20)(21)(22). Unfortunately, 2-(4-aminophenyl)propan-2-ol (16), bearing an free amine (NH 2 ), was not compatible with this reaction.…”

Homolytic, Heterolytic, Mesolytic ‐ As You Like It: Steering the Cleavage of a HC(sp3)−C(sp3)H Bond in Bis(1H‐2,1‐benzazaborole) Derivatives

“…The utilization of various types of monoanionic C, N-or N, C, Nchelating ligands, enabling the closure of af ive-membered chelating ring (built up as (bis)ortho-functionalized aryls) is ubiquitous in the chemistry of main group elements. [1] These ligands contain ap endant amino donorg roup in most cases. Despitet he fact that they facilitated the isolation of ap lethora of interesting and unprecedented compounds,a tl east from the structurala nd fundamental point of view,t hey generally behavea ss pectator ligands.…”

“…Despitet he fact that they facilitated the isolation of ap lethora of interesting and unprecedented compounds,a tl east from the structurala nd fundamental point of view,t hey generally behavea ss pectator ligands. [1,2] Recently,anew approach appeared, based on the substitution of relatively chemically inert and redox-innocent amino moieties by corresponding imino donor groups. [3] It is obvious that this pendant HC=Ng roup exhibits ap ronounced tendency to undergo furtherc hemical transformationsu pon coordination to the central element, ap roperty typicalf or so-called actor ligands.…”