title: Novel imidazolium and imidazolinium salts containing the 9-nickelafluorenyl anion--synthesis, structures and reactivity.
abstract: Investigation of the properties of carbene complexes is one of the most important fields of modern coordination chemistry. In this paper, we propose the convenient synthesis of NHC-nickel compounds. The 9-nickelafluorenyllithium complex reacts with imidazolium or imidazolinium salts to afford 9-nickelafluorenyl-NHC salts via ionic metathesis with very good yields (66-92%). These compounds can be isomerised at elevated temperatures to give Ni-NHC complexes with excellent yields (88-91%), probably via nickel mediated hydrogen transfer to the biphenyl moiety. In this reaction, the nickelacyclic ring itself serves as a base in the deprotonation of the carbene precursor. DFT calculations show the thermodynamic instability of the synthesized salts, with Gibbs free energy differences for 1 of -84 kJ mol(-1) at 298 K and -167 kJ mol(-1) at 374 K. The obtained salts and carbene complexes are relatively air and moisture stable in the solid state.
authors.affiliation: Warsaw University of Technology, Faculty of Chemistry, Koszykowa 75, 00-662 Warsaw, Poland. pjb@ch.pw.edu.pl.
authors.forename: Piotr
authors.initials: P
authors.lastname: Buchalski
authors.forename: Roman
authors.initials: R
authors.lastname: Pacholski
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Chodkiewicz
authors.forename: Włodzimierz
authors.initials: W
authors.lastname: Buchowicz
authors.forename: Kinga
authors.initials: K
authors.lastname: Suwińska
authors.forename: Aleksander
authors.initials: A
authors.lastname: Shkurenko