Positively charged ligands. The synthesis, structure, and bonding of sulfonium ion complexes of transition metals and evidence for a metal-induced acceleration of their dealkylation

Coordination chemistry of methyl iodide

“…In particular a chiral alkylating agent should in principle be possible, given a chiral Lewis acidic metal fragment. Adams et al 21 showed that coordinating Me3S+ led to rate (16) Sahni, R. C. Trans. Faraday Soc.…”

Sulfonium Salts. Participants par Excellence in Metal-Catalyzed Carbon−Carbon Bond-Forming Reactions

“…With appropriate non-nucleophilic counterions (PF 6 , BF 4 , ClO 4 17 ), they possess good solubility and stability in both aprotic and protic solvents. As synthetically versatile cationic cross-coupling reactants, they offer a reactivity advantage through participation in attractive Coulombic interactions with approaching nucleophiles, and although cationic, sulfonium salts can coordinate to (and be activated by) a metal catalyst through the nonbonding pair of electrons on sulfur. , These attractive features and the biological relevance of metal-mediated carbon−sulfur bond cleavage led to the current study, documented herein, which revealed the synthetic power of sulfonium salts in metal-catalyzed cross-coupling reactions (see Table ).…”

Does H3O+ Really Act as a Ligand in the Solid State?

“…First, the H 3 O + ion is cationic. Although complexes containing cationic ligands have been crystallographically characterized, such ligands often involve significant charge delocalization and the donor atom itself is not formally positively charged. − Neither of these factors is applicable for the small and highly polarizing H 3 O + ion, which will render any electron pair donation from this cationic species to a transition-metal ion weak at best. Second, H 3 O + is the strongest Brønsted acid that can exist in aqueous solution and shows little, if any, basic properties toward a proton: that is, the H 4 O 2+ dication does not exist .…”