C-F bond activation by transient phosphenium dications.

C-F bond cleavage by transient phosphorus(III)-based dications [RP(C(PPh3)2)](2+) (4a(2+), R = Ph; 4b(2+), R = 4-F-Ph) is reported. These dications were generated by reaction of the corresponding monocationic precursors with excess Na[BAr4(Cl)]. Evidence for the existence of transient dicationic species was obtained by trapping the dication 4a(2+) with PMe3. According to theoretical analysis, the low-lying lowest unoccupied molecular orbitals of these species were responsible for the observed activation of C-F bonds.

Oxidative addition of water and methanol to a dicationic trivalent phosphorus centre.

Our recently synthesised phosphorus dication is observed to activate water (and methanol) under reactions conditions atypical for other systems containing a non-metal centre. This particular activation described as oxidative addition is quite rare and has been reserved exclusively for a couple of metal-based compounds.

Dihaloborenium cations stabilized by a four-membered N-heterocyclic carbene: electron deficiency compensation by asymmetric structural changes.

The synthesis, characterization and X-ray analysis of dichloro- and dibromo-borenium cations stabilized by a 4-membered carbene are reported. The ligand's structural changes, atypical for similar systems, were caused by coordination to electron deficient fragments and its CN2P ring strain.