title: 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.).
abstract: 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 )2 and 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.
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany. petz@staff.uni-marburg.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Petz
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany. kuzui@staff.uni-marburg.de.
authors.forename: Istemi
authors.initials: I
authors.lastname: Kuzu
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany. frenking@staff.uni-marburg.de.
authors.forename: Gernot
authors.initials: G
authors.lastname: Frenking
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany.
authors.forename: Diego M
authors.initials: DM
authors.lastname: Andrada
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany. neumuell@chemie.uni-marburg.de.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Neumüller
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Fritz
authors.affiliation: Fachbereich Chemie der, Philipps-Universität, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany.
authors.forename: Jörn E
authors.initials: JE
authors.lastname: Münzer
keywords: bonding analysis; carbone adducts; proton affinities; quantum chemical calculations