88410-12-2Relevant articles and documents
Proton Affinities of Cationic Carbone Adducts [AC(PPh3)2]+(A=Halogen, Hydrogen, Methyl) and Unusual Electronic Structures of the Cations and Dications [AC(H)(PPh3)2]2+
Petz, Wolfgang,Kuzu, Istemi,Frenking, Gernot,Andrada, Diego M.,Neumüller, Bernhard,Fritz, Maximilian,Münzer, J?rn E.
, p. 8536 - 8546 (2016)
This work reports the syntheses and the first crystal structures of the cationic carbone adducts [FC(PPh3)2]+and [BrC(PPh3)2]+and the protonated dication [FC(H)(PPh3)2]2+, which are derived from the carbone C(PPh3)2. Quantum chemical calculations and bonding analyses were carried out for the series of cations [AC(PPh3)2]+and dications [AC(H)(PPh3)2]2+, where A=H, Me, F, Cl, Br, I. The bonding analysis suggests that the cations are best described as phosphane complexes L→(CA)+←L (L=PPh3), which are related to the neutral borylene adducts L→(BA)←L (L=cyclic carbene; A=H, aryl) that were recently isolated. The carbone adducts [AC(PPh3)2]+possess a π electron lone pair at carbon and they can easily be protonated to the dications [AC(H)(PPh3)2]2+. The calculations of the dications indicate that the molecules are best represented as complexes L→(CHA)2+←L (L=PPh3) where a carbene dication is stabilized by the ligands. The central carbon atom in the cations and even in the dications carries a negative partial charge, which is larger than the negative charge at fluorine. There is also the peculiar situation in which the carbon–fluorine bonds in [FC(PPh3)2]+and [FC(H)(PPh3)2]2+exhibit the expected polarity with the negative end at fluorine, but the carbon atom has a larger negative charge than fluorine. Given the similarity of carbodiphosphorane C(PPh3)2and carbodicarbene C(NHC)2, we expect that analogous compounds [AC(NHC)2]+and [AC(H)(NHC)2]2+with similar features as [AC(PPh3)2]+and [AC(H)(PPh3)2]2+can be isolated.
