The oxidative addition of aryl electrophiles is a fundamental organometallic reaction widely applied in the field of transition metal chemistry and catalysis. However, the analogous version based on main group elements still remains largely underexplored. Here, we report the ability of a well-defined organobismuth(I) complex to undergo formal oxidative addition with a wide range of aryl electrophiles. The process is facilitated by the reactivity of both the ground and excited states of N,C,N-bismuthinidenes upon absorption of low-energy red light.

Nanosized SSZ-13 was synthesized hydrothermally by applying N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as a structure-directing agent. In the next step, the quantity of TMAdaOH in the initial synthesis mixture of SSZ-13 was reduced by half. Furthermore, we varied the sodium hydroxide concentration. After ion-exchange with copper ions (Cu²⁺ and Cu⁺), the Cu-SSZ-13 catalysts were characterized to explore their framework composition (XRD, solid-state NMR, ICP-OES), texture (N₂-sorption, SEM) and acid/redox properties (FT-IR, TPR-H₂, DR UV-Vis, EPR). Finally, the materials were tested in the selective catalytic reduction of NO_x with ammonia (NH₃-SCR). The main difference between the Cu-SSZ-13 catalysts was the number of Cu²⁺ in the double six-membered ring (6MRs). Such copper species contribute to a high NH₃-SCR activity. Nevertheless, all materials show comparable activity in NH₃-SCR up to 350 °C. Above 350 °C, NO conversion decreased for Cu-SSZ-13(2–4) due to side reaction of NH₃ oxidation.

The bonding of copper ions to lattice oxygens dictates the activity and selectivity of copper exchanged zeolites. By ¹⁷O isotopic labelling of the zeolite framework, in conjunction with advanced EPR methodologies and DFT modelling, we determine the local structure of single site Cu^II species, we quantify the covalency of the metal-framework bond and we assess how this scenario is modified by the presence of solvating H₂¹⁶O or H₂¹⁷O molecules. This enables to follow the migration of Cu^II species as a function of hydration conditions, providing evidence for a reversible transfer pathway within the zeolite cage as a function of the water pressure. The results presented in this paper establish ¹⁷O EPR as a versatile tool for characterizing metal-oxide interactions in open-shell systems.

Within the emerging field of bismuth redox catalysis, the catalytic formation of C−C bonds using aryl halides would be highly desirable; yet such a process remains a synthetic challenge. Herein, we present a chemoselective bismuth‐photocatalyzed activation and subsequent coupling of (hetero)aryl iodides with pyrrole derivatives to access C(sp²)−C(sp²) linkages through C−H functionalization. This unique reactivity is the result of the bismuth complex featuring two redox state‐dependent interactions with light, which 1) activates the Bi(I) complex for oxidative addition via MLCT, and 2) promotes the homolytic cleavage of aryl Bi(III) intermediates through a LLCT process.

Despite the progress made in the field of synthetic organic photocatalysis over the past decade, the use of higher wavelengths, especially those in the deep-red portion of the electromagnetic spectrum, remains comparatively rare. We have previously disclosed that a well-defined N,C,N-pincer bismuthinidene (1a) can undergo formal oxidative addition into a wide range of aryl electrophiles upon absorption of low-energy red light. In this study, we map out the photophysical dynamics of 1a and glean insights into the nature of the excited state responsible for the activation of aryl electrophiles. Transient absorption and emission techniques reveal that, upon irradiation with red light, the complex undergoes a direct S₀ → S₁ metal-to-ligand charge transfer (MLCT) transition, followed by rapid intersystem crossing (ISC) to a highly reducing emissive triplet state (-2.61 V vs Fc^+/0 in MeCN). The low dissipative losses incurred during ISC (∼6% of the incident light energy) help rationalize the ability of the bismuthinidene to convert low-energy light into useful chemical energy. Spectroelectrochemical and computational data support a charge-separated excited-state structure with radical-anion character on the ligand and radical-cation character on bismuth. Kinetic studies and competition experiments afford insights into the mechanism of oxidative addition into aryl iodides; concerted and inner-sphere processes from the triplet excited state are ruled out, with the data strongly supporting a pathway that proceeds via outer-sphere dissociative electron transfer.

Using EPR and HYSCORE spectroscopies in conjunction with ab initio calculations, we assess the structure of framework-bound monomeric hydroxo-Cu^II in copper-loaded chabazite (CHA). The species is an interfacial distorted square-planar [Cu^IIOH(O-8MRs)₃] complex located at eight-membered-ring windows, displaying three coordinating bonds with zeolite lattice oxygens and the hydroxo ligand hydrogen-bonded to the cage. The complex has a distinctive EPR signature with g = [2.072 2.072 2.290], ^CuA= [30 30 410] MHz, and ^HA = [-13.0 -4.5 +11.5] MHz, distinctively different from other Cu^II species in CHA.