A Redox‐Confused Bismuth(I/III) Triamide with a T‐Shaped Planar Ground State

Abstract

Reaction of a tethered triamine ligand with Bi(NMe2)3 gives a Bi triamide, for which a BiI electronic structure is shown to be most appropriate. The T‐shaped geometry at bismuth provides the first structural model for edge inversion in bismuthines and the only example of a planar geometry for pnictogen triamides. Analogous phosphorus compounds exhibit a distorted pyramidal geometry because of different Bi−N and P−N bond polarities. Although considerable BiI character is indicated for the title Bi triamide, it exhibits reactivity similar to BiIII electrophiles, and expresses either a vacant or a filled p orbital at Bi, as evidenced by coordination of either pyridine N‐oxide or W(CO)5. The product of the former shows evidence of coordination‐induced oxidation state change at bismuth.

Fluorination of arylboronic esters enabled by bismuth redox catalysis

“…of BF 3 •OEt 2 (Et, ethyl group) at -45°C (Fig. 3B), exclusive formation of 25 was confirmed in solution by 1 H, 11 B, 19 F, and 13 C nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). When this complex was heated to 60°C, fluorobenzene (3) was formed in just 5 min, with concomitant formation of tetrafluoroborate bismine (26).…”

“…However, the exploitation of the redox properties of main-group elements in catalysis to access new modes of reactivity is still in its infancy (17) and remains a major challenge in organometallic and organic chemistry. We therefore focused our attention on bismuth (Bi), an Earthabundant and inexpensive main-group element (18) with under-explored redox properties (19). The use of Bi in catalysis has relied largely on its Lewis acidic properties (20), where recent interest has revitalized its use in fields such as C-H activation (21), carbonylation (22), transfer hydrogenation (23), and as the initiator in radical processes (24)(25)(26).…”

Catalytic Fluorination of Boron Compounds at a Bismuth Redox Platform

“…), CH3CN, 90 ºC, 16 h. B. Two-step method for the fluorination of boronic acids. In parenthesis, yields for step 1 (isolated) and step 2 (determined by 19 F NMR), respectively. Step 1: chlorobismine 29 (1.0 equiv.…”

“…Although these strategies represent excellent platforms for chemical synthesis, the quest for developing methodologies based on the redox properties of a main-group element that surpass the reactivity of transition metals remains one of the most sought challenges in organometallic and organic chemistry. Towards this goal, we focused our attention on bismuth (Bi); an Earthabundant, non-toxic and inexpensive main-group element (18), whose redox properties have been largely underexplored (19). The use of Bi in catalysis has been restricted to its Lewis acidic properties (20), and recent interest has revitalized its use in fields such as C-H activation (21), carbonylation (22) and transfer hydrogenation (23).…”

Hydrostibination of Alkynes: A Radical Mechanism

“…[14][15][16][17][18][19] The addition of antimony hydrides (primary or secondary stibines) to multiple bondshydrostibination -has been explored to a very limited extent, 20,21 with well-defined examples being restricted to cases that proceed under Lewis-acid or radical-initiator (azobisisobutyronitrile, AIBN) mediated conditions. 22,23 As part of our exploration into new structure and reactivity at antimony and bismuth centres, 24,25 we recently reported the first definitive catalyst-and additive-free addition of stibines to alkenes, alkynes, ketones, and azobenzene. The reaction proceeds under ambient conditions with near-quantitative yields (Figure 1b), 26 and is directly analogous to uncatalyzed hydroboration, furthering our unusual proposal of a "diagonal relationship" 27,28 between the lightest p-block element and heavy Group 15 metals.…”