title: Reactivity-Tuning in Frustrated Lewis Pairs: Nucleophilicity and Lewis Basicity of Sterically Hindered Phosphines.
abstract: The nucleophilicity and Lewis basicity of sterically hindered phosphines, widely used in catalysis and in frustrated Lewis pair (FLP) chemistry, have been quantified by determining the rates and equilibrium constants of their associations with reference systems (benzhydrylium and tritylium ions) of calibrated electrophilicities and Lewis acidities. These structure-reactivity investigations allow a rationalization of the Lewis acid-base interactions all along the way from covalent Lewis adducts to FLPs. Comparisons of the association of phosphines of increasing sizes (Ph3P, (o-tolyl)3P, and tBu3P) with the triarylborane B(C6F5)3and with the isoelectronic tritylium ions Ar3C+provide detailed insights for the future fine-tuning of the reactivities of FLPs. As a proof of concept, tritylium-ion-derived FLPs were shown to react with alkynes, as reported for the FLPs derived from the benchmark triarylborane B(C6F5)3.
authors.affiliation: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.
authors.forename: Elsa
authors.initials: E
authors.lastname: Follet
authors.affiliation: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Mayer
authors.affiliation: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.
authors.forename: David S
authors.initials: DS
authors.lastname: Stephenson
authors.affiliation: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.
authors.forename: Armin R
authors.initials: AR
authors.lastname: Ofial
authors.affiliation: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.
authors.forename: Guillaume
authors.identifier: http://orcid.org/0000-0002-5422-9113
authors.initials: G
authors.lastname: Berionni
keywords: Lewis adducts; Lewis bases; frustrated Lewis pairs; phosphines; reactivity scales