title: Experimental Basicities of Superbasic Phosphonium Ylides and Phosphazenes.
abstract: Experimental basicities of some of the strongest superbases ever measured (phosphonium ylides) are reported, and by employing these compounds, the experimental self-consistent basicity scale of superbases in THF, reaching a pKα (estimate of pKa) of 35 and spanning more than 30 pKa units, has been compiled. Basicities of 47 compounds (around half of which are newly synthesized) are included. The solution basicity of the well-known t-Bu-N═P4(dma)9 phosphazene superbase is now rigorously linked to the scale. The compiled scale is a useful tool for further basicity studies in THF as well as in other solvents, in particular, in acetonitrile. A good correlation between basicities in THF and acetonitrile spanning 25 orders of magnitude gives access to experimentally supported very high (pKa > 40) basicities in acetonitrile, which cannot be directly measured. Analysis of structure-basicity trends is presented.
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Jaan
authors.initials: J
authors.lastname: Saame
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Toomas
authors.initials: T
authors.lastname: Rodima
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Sofja
authors.initials: S
authors.lastname: Tshepelevitsh
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Agnes
authors.initials: A
authors.lastname: Kütt
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Ivari
authors.initials: I
authors.lastname: Kaljurand
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Tõiv
authors.initials: T
authors.lastname: Haljasorg
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Ilmar A
authors.initials: IA
authors.lastname: Koppel
authors.affiliation: Institute of Chemistry, University of Tartu , 14a Ravila Str, 50411 Tartu, Estonia.
authors.forename: Ivo
authors.initials: I
authors.lastname: Leito