title: Experimental gas-phase basicity scale of superbasic phosphazenes.
abstract: Seventeen superbasic phosphazenes and two Verkade's bases were used to supplement and extend the experimental gas-phase basicity scale in the superbasic region. For 19 strong bases the gas-phase basicity values (GB) were determined for the first time. Among them are such well-known bases as BEMP (1071.2 kJ/mol), Verkade's Me-substituted base (1083.8 kJ/mol), Et-N=P(NMe2)2-N=P(NMe2)3 (Et-P2 phosphazene, 1106.9 kJ/mol), and t-Bu-N=P(NMe2)3 (t-Bu-P1 phosphazene, 1058.0 kJ/mol). For the first time experimental GB values were determined for P2 phosphazenes. Together with our previous results self-consistent experimental gas-phase basicity scale between 1020 and 1107 kJ/mol is now established. This way an important region of the gas-phase basicity scale, which was earlier dominated by metal hydroxide bases, is now covered also with organic bases making it more accessible for further studies. The GB values for several superbases were calculated using density functional theory at the B3LYP/6-311+G** level. For the phosphazene family the standard deviation of the correlation between the experimental and theoretical values was 6.5 kJ/mol.
authors.affiliation: Department of Chemistry, University of Tartu, Jakobi 2 str, 51014 Tartu, Estonia.
authors.forename: Ivari
authors.initials: I
authors.lastname: Kaljurand
authors.forename: Ilmar A
authors.initials: IA
authors.lastname: Koppel
authors.forename: Agnes
authors.initials: A
authors.lastname: Kütt
authors.forename: Eva-Ingrid
authors.initials: EI
authors.lastname: Rõõm
authors.forename: Toomas
authors.initials: T
authors.lastname: Rodima
authors.forename: Ivar
authors.initials: I
authors.lastname: Koppel
authors.forename: Masaaki
authors.initials: M
authors.lastname: Mishima
authors.forename: Ivo
authors.initials: I
authors.lastname: Leito