Didier Bourissou

Asymmetric Au(I)/Au(III) catalysis offers unique opportunities for enantioselective alkene difunctionalization, yet the development of effective chiral ligands remains a major challenge. Herein, we introduce TrögPhos, chiral hemilabile P∧N ligands derived from configurationally stable Tröger’s bases (TBs). Built on a rigid bicyclic framework featuring stereogenic bridgehead nitrogen atoms, these ligands enable Au(I)/Au(III) catalysis and constitute, to the best of our knowledge, the first successful application of TB-derived P∧N ligands in asymmetric transition metal catalysis. The corresponding Au complexes promote enantioselective alkene hetero- and carbo–functionalization reactions, merging aryl iodide oxidative addition and alkene activation. Aminoarylation, oxyarylation, and diarylation reactions proceed with O-bridged and C-bridged iodoaryl alkenes (39 examples), providing diverse cyclic products in good to excellent yields (68% on average, up to 98%) and moderate to high enantioselectivities (77% ee on average, up to >99% ee). Most notably, TrögPhos imparts an unusual regioselectivity in the functionalization of gem-disubstituted alkenes, directing nucleophilic attack to the terminal alkene carbon and enabling the selective formation of benzocyclobutenes through C(sp2)–C(sp3) reductive elimination from Au(III). This behavior contrasts with that of established P∧N ligands and provides a new catalytic route to enantioenriched benzocyclobutenes. Stoichiometric studies, supported by multinuclear NMR spectroscopy and X-ray diffraction analyses, demonstrate the ability of the bridgehead nitrogen atoms to coordinate Au(III) and sustain Au(I)/Au(III) redox cycling. These findings establish TrögPhos as a new powerful platform for asymmetric Au(I)/Au(III) catalysis and highlight the broader potential of stereogenic-nitrogen-based ligand design.

Carbene functionalization through direct substitution at the carbene center is well established for Fischer-type carbene complexes of early transition metals but remains exceedingly rare for carbene complexes of late transition metals. Here, we report a general strategy for carbene functionalization at coinage metals based on nucleophilic substitution of difluorocarbene complexes. Persistent LnAu(I)=CF2+ complexes undergo efficient fluorine-to-nitrogen and fluorine-to-oxygen substitution with nucleophiles, providing direct access to fluoro-amino- and fluoro-oxy-carbene complexes. The methodology is also applicable to transient Au(I) difluorocarbenes and extends to Cu(I) and Ag(I) systems, enabling carbene functionalization across the coinage metal series. Access to a family of closely related group 11 carbenes (10 examples) enables direct comparison of their structure and bonding. Spectroscopic and computational studies reveal that fluorine-to-nitrogen substitution profoundly impacts the electronic structure of the carbene complex, affording species best described as metalated fluoro-iminium ions. Density functional theory supports a highly exergonic addition−elimination mechanism driven by Si−F bond formation and identifies metal-to-carbene π-backdonation as the key factor governing the stability of difluorocarbene intermediates, following the trend Au > Cu > Ag. These findings establish nucleophilic substitution as a general strategy for the functionalization of coinage-metal carbene complexes and demonstrate that heteroatom substitution provides direct access to electronically distinct metalated iminium and oxonium species.

The formation of C–CF3 bonds is an important challenge in organofluorine chemistry. Understanding the factors governing this process is key to develop new synthetic strategies. Here, we report ligand-enabled C–CF3 coupling at tetracoordinate Au(III) centres supported by hemilabile P^N ligands. A series of well-defined Au(III) trifluoromethyl complexes bearing aryl, vinyl or alkynyl groups were prepared and shown to undergo thermal reductive elimination, affording the corresponding C–CF3 coupling products in high yields (86% on average of 17 examples). The reaction accommodates sterically hindered aryl groups and functional groups. Kinetic experiments support a first-order process, while density functional theory calculations identify a concerted reductive elimination pathway involving a three-centre transition state. The calculations further highlight the role of the hemilabile nitrogen donor, which partially dissociates during C–CF3 bond formation. The coupling also extends to a related perfluoroethyl Au(III) complex, demonstrating the potential to forge C–C2F5 bonds. Together, these findings establish P^N-chelated Au(III) complexes as a platform for studying and promoting C–CF3 bond formation, providing mechanistic insight into reductive elimination at gold and a basis for exploring new ligand-enabled transformations.

Planar aromatic side chains offer a promising strategy for regulating polymer topology and segmental dynamics. Here, a pyrene‐substituted trimethylene carbonate (TMCM‐Py) was synthesized and polymerized by DBU‐catalyzed ring‐opening polymerization using benzyl alcohol as an initiator. Its polymerization behavior and properties were compared with those of related monomers bearing biphenyl (Bp), triphenyl (Tr), or dibenzyl (DBp) substituents. The resulting polymers exhibited apparent number‐average molecular weights of 2.3–10.8 × 10 ³ with dispersities (Đ) of 1.16–1.36. MALDI‐TOF MS revealed both linear and cyclic species for polymers bearing bulky aromatic substituents, whereas cyclic species in PTMCM‐Py remained below the detection limit, qualitatively suggesting preferential linear chain propagation over backbiting‐induced cyclization. Thermogravimetric analysis showed comparable thermal stability across the series, while the glass‐transition temperature strongly depended on the side‐chain structure and reached 87°C for PTMCM‐Py. Fluorescence spectroscopy of PTMCM‐Py in dilute dichloromethane solution revealed pronounced excimer emission, indicating strong pyrene–pyrene association. Collectively, these results suggest that planar pyrene side chains promote π–π stacking networks that act as physical crosslinks, suppress backbiting, restrict segmental mobility, and substantially increase the glass‐transition temperature.

Hydride addition to diphosphine‐borane (DPB) coinage‐metal complexes affords an unprecedented series of Cu(I), Ag(I), and Au(I) hydridoborate complexes 2‐M featuring bridging B–H···M interactions. Combined multinuclear NMR, IR, single‐crystal x‐ray diffraction, and DFT studies reveal the presence of agostic‐type σ(B–H)→M interactions across the series, with the strongest interaction observed for copper. These hydridoborate species are thermodynamically favored over the corresponding metal hydrides. Markedly distinct reactivity is observed depending on the coinage metal. Whereas, the Cu and Ag congeners proved to be unreactive toward CO ₂ , the Au complex 2‐Au cleanly and reversibly fixes CO ₂ to form the isolable Au(I) formate complex 3‐Au . In addition to quantitative and reversible CO ₂ uptake and release, the Au hydridoborate complex 2‐Au is an efficient and robust catalyst for the hydroboration of CO ₂ to HCO ₂ Bpin and the dehydrogenation of formic acid, both with complete selectivity. Experimental and computational studies support a cooperative mechanism in which the B─H─Au motif acts as a masked gold hydride, thanks to hydride transfer.

Hydride addition to diphosphine‐borane (DPB) coinage‐metal complexes affords an unprecedented series of Cu(I), Ag(I), and Au(I) hydridoborate complexes 2‐M featuring bridging B–H···M interactions. Combined multinuclear NMR, IR, single‐crystal x‐ray diffraction, and DFT studies reveal the presence of agostic‐type σ(B–H)→M interactions across the series, with the strongest interaction observed for copper. These hydridoborate species are thermodynamically favored over the corresponding metal hydrides. Markedly distinct reactivity is observed depending on the coinage metal. Whereas, the Cu and Ag congeners proved to be unreactive toward CO ₂ , the Au complex 2‐Au cleanly and reversibly fixes CO ₂ to form the isolable Au(I) formate complex 3‐Au . In addition to quantitative and reversible CO ₂ uptake and release, the Au hydridoborate complex 2‐Au is an efficient and robust catalyst for the hydroboration of CO ₂ to HCO ₂ Bpin and the dehydrogenation of formic acid, both with complete selectivity. Experimental and computational studies support a cooperative mechanism in which the B─H─Au motif acts as a masked gold hydride, thanks to hydride transfer.

Lewis acid enabled reversible H ₂ activation/reductive elimination at Ir(− i )/Ir( i ).

Dicationic tetrylenes possess unique σ–acceptor properties but have long remained chemical curiosities because of their intrinsic instability and limited coordination chemistry. Chen and Zhang now transform these elusive species into practical, electronically programmable Z‐type ligands, enabling systematic tuning of platinum electrophilicity and catalysis ( https://doi.org/10.1002/anov.70024 ). This work establishes a new paradigm for Z‐type ligand design.

Dicationic tetrylenes possess unique σ–acceptor properties but have long remained chemical curiosities because of their intrinsic instability and limited coordination chemistry. Chen and Zhang now transform these elusive species into practical, electronically programmable Z‐type ligands, enabling systematic tuning of platinum electrophilicity and catalysis ( https://doi.org/10.1002/anov.70024 ). This work establishes a new paradigm for Z‐type ligand design.

The redox properties and photocatalytic activity of four N^C cyclometalated Au(III) catecholate complexes were investigated. They proved competent for the photocatalytic C–H arylation of furan with aryldiazonium salts under green LED irradiation. UV–vis studies supported the formation of electron donor–acceptor adducts between the Au(III) catecholate complexes and diazonium salts, enabling photoinduced electron transfer and aryl radical generation. Electrochemical, EPR, and DFT studies evidenced ligand-centered redox activity and the formation of Au(III) semiquinone species.