Isolable Coinage Metal Propylene Complexes and Trigonal Pyramids with Tris(pyridyl)borate Ligands

The fluorinated tris(pyridyl)borate ligand [MeB(6-(CF 3 )Py) 3 ] − provides access to a series of isoleptic, coinage-metal propylene complexes, [MeB(6-(CF 3 )Py 3 ]M(C 3 H 6 ) (M = Cu, Ag, Au), which were isolated and thoroughly characterized. Tris(pyridyl)borate coordinates to metal ions in a κ 2 -fashion. The copper(I) and silver(I) derivatives exhibit reversible propylene binding, and loss of the olefin affords the propylene-free species [MeB(6-(CF 3 )Py) 3 ]M (M = Cu, Ag), featuring three-coordinate, trigonal pyramidal metal sites. Theoretical studies of [MeB(6-(CF 3 )Py 3 ]M(C 3 H 6 ) show that the metal–propylene interaction is strongest in gold(I), followed by copper(I) and silver(I), with bonding involving significant metal-to-alkene π-backdonation, which is relatively stronger than alkene-to-metal σ-donation in all three complexes. The electrostatic component in metal–propylene interaction in these complexes is quite strong. Solid-state structural data and solution NMR data of [MeB(6-(CF 3 )Py 3 ]M(C 3 H 6 ) are consistent with these inferences. Gas adsorption studies of solid [MeB(6-(CF 3 )Py) 3 ]M (M = Cu, Ag) show a higher uptake of propane than propylene, indicating that host–guest interactions within the fluorinated ligand environment play a dominant role in the adsorption behavior. Aziridination studies demonstrate that the copper complex is effective in nitrene transfer reactions to alkenes, highlighting the potential of fluorinated poly(pyridyl)borate ligand supports in catalysis applications.