title: Formation, structural characterization, and reactions of a unique cyclotrimeric vicinal Lewis pair containing (C6F5)2P-Lewis base and (C6F5)BH-Lewis acid components.
abstract: The synthesis of the new vicinal frustrated Lewis pair 5 containing (C6F5)2P-Lewis base and (C6F5)BH-Lewis acid functionality is described. It forms a unique cyclotrimer (5)3 which was structurally characterized by X-ray crystallography and high-resolution solid-state NMR spectroscopy. The relevant NMR Hamiltonian parameters ((11)B and (31)P chemical shielding tensors, (11)B quadrupolar coupling tensors, and (31)P-(11)B spin-spin coupling constants) indicate significant intramolecular covalent BP interactions, consistent with results from density functional theory (DFT) calculations. In addition, the (11)B/(31)P and (31)P/(31)P three-spin geometries are accurately reproduced by suitable high-resolution hetero- and homonuclear dipolar NMR experiments. As predicted from the bonding character portrayed by the solid-state NMR results, the cyclotrimer (5)3 possesses only moderate catalytic activity. However, it undergoes an addition reaction with pyridine and hydroboration reactions with benzaldehyde and tert-butylacetylene. The products of the hydroboration reactions form stable adducts with pyridine.
authors.affiliation: Organisch-Chemisches Institut, WWU Münster, Corrensstraße 40, D 48149 Münster, Germany. erker@uni-muenster.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Erdmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Wiegand
authors.forename: Jonas
authors.initials: J
authors.lastname: Blumenberg
authors.forename: Hellmut
authors.initials: H
authors.lastname: Eckert
authors.forename: Jinjun
authors.initials: J
authors.lastname: Ren
authors.forename: Constantin G
authors.initials: CG
authors.lastname: Daniliuc
authors.forename: Gerald
authors.initials: G
authors.lastname: Kehr
authors.forename: Gerhard
authors.initials: G
authors.lastname: Erker