A variety of chemical transformations benefit from the use of strong electron-donating ancillary ligands, such as alkylphosphines or N-heterocyclic carbenes when electron-rich metal centers are required. Herein, we describe a facile and highly modular access to monodentate and bidentate imidazolin-2-ylidenamino-substituted phosphines. Evaluation of the phosphine's electronic properties substantiate that the formal replacement of alkyl or aryl groups by imidazolin-2-ylidenamino groups dramatically enhance their donor ability beyond that of alkylphosphines and even N-heterocyclic carbenes. The new phosphines have been coordinated onto palladium(II) centers, and the beneficial effect of the novel substitution patterns has been explored by using the corresponding complexes in the palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of non-activated aryl chloride substrates.

For the efficient utilization of carbon dioxide as feedstock in chemical synthesis, low-energy-barrier CO2 activation is a valuable tool. We report a metal-free approach to reversible CO2 binding under mild conditions based on simple Lewis base adducts with electron-rich phosphines. Variable-temperature NMR studies and DFT calculations reveal almost thermoneutral CO2 binding with low-energy barriers or stable CO2 adduct formation depending on the phosphines donor ability. The most basic phosphine forms an air-stable CO2 adduct that was used as phosphine transfer agent, providing a convenient access to transition-metal complexes with highly electron-rich phosphine ligands relevant to catalysis.

A systematic study on the formation of isolable nitrogen base–CO2 adducts is reported giving rise to the first water-stable adducts.

The development of new methods for the chemical activation of the extremely inert greenhouse gas sulfur hexafluoride (SF ) not only is of current environmental interest, but also offers new opportunities for applications of SF as a reagent in organic synthesis. We herein report the first nucleophilic activation of SF by Lewis bases, namely by phosphines, which results either in its complete degradation to phosphine sulfides and difluorophosphoranes or in the selective conversion of SF into a bench-stable, crystalline salt containing the SF anion. Quantum chemical calculations reveal a nucleophilic substitution mechanism (S 2) for the initial fluorine abstraction from SF by the phosphine. Furthermore, a scalable one-pot procedure for the complete decomposition of SF into solid, nonvolatile products is presented based on cheap and commercially available starting materials.

The particularly basic phosphines 1a-c readily form isolable, zwitterionic Lewis base adducts with SO that were fully characterized including by X-ray diffraction studies. Computational and reactivity studies show that these adducts readily release SO at room temperature driven by the formation of the corresponding phosphine oxides.