Bonding Energetics in Alkaline Metal Alkoxides and Phenoxides

Abstract

The bonding energetics in a variety of alkaline metal, alkoxides and phenoxides, MOR, was investigated based on the corresponding enthalpies of formation in the crystalline state determined by reaction-solution calorimetry. The results obtained at 298.15 K were as follows: Delta(f)H(m)(o)(MOR, cr)/kJ mol(-1) = 382.7+/-1.4 (LiOC(6)H(5)), 513.6+/-2.5 (NaO-nC(6)H(13)), 326.4+/-1.4 (NaOC(6)H(5)), 375.2+/-3.4 (KOCH(3)), 434.5+/-2.7 (KOC(2)H(5)), 467.1+/-5.2 (KO-nC(3)H(7)), 459.3+/-2.1 (KO-nC(4)H(9)), 464.6+/-5.7 (KO-tC(4)H(9)), 464.3+/-2.5 (KO-nC(6)H(13)), 333.3+/-3.1 (KOC(6)H(5)), 380.6+/-2.9 (RbOCH(3)), 434.1+/-2.9 (RbOC(2)H(5)), 345.3+/-2.9 (LiOC(6)H(5)), 379.1+/-3.0 (CsOCH(3)), 432.3+/-3.1 (CsOC(2)H(5)), 466.9+/-5.0 (CsO-nC(3)H(7)), 461.3+/-3.5 (CsO-nC(4)H(9)), 461.9+/-2.5 (CsO-tC(4)H(9)), 349.2+/-1.4 (CsOC(6)H(5)). These results together with revised Delta(f)H(m)(o)(MOR, cr) values from the literature, were used to derive a consistent set of lattice energies for the MOR compounds and discuss general trends in the structure-energetics relationship based on the Kapustinskii equation.

Synthesis and Reactivity of Dioxazirconacyclohexenes: Development of a Zirconium–Oxo-Mediated Alkyne–Aldehyde Coupling Reaction

“…It was found that using CsHMDS as the base greatly accelerated the rate of the reaction, relative to other alkali-metal cations . One possible explanation for the significant counterion effect is that the rate of elimination from Cp* 2 Zr(O – X + )OTf is dependent on the counterion, with the weaker ionic bond between [Zr]–O – and Cs + leading to faster reaction rates . Alternatively, as the elimination reaction is heterogeneous, the Cs cation may have increased solubility and therefore faster reaction rates .…”

“…12 One possible explanation for the significant counterion effect is that the rate of elimination from Cp* 2 Zr(O − X + )OTf is dependent on the counterion, with the weaker ionic bond between [Zr]−O − and Cs + leading to faster reaction rates. 13 Alternatively, as the elimination reaction is heterogeneous, the Cs cation may have increased solubility and therefore faster reaction rates. 14 The subsequent carbonyl insertion into p-trifluoromethylbenzaldehyde occurs cleanly at room temperature to afford the dioxazirconacyclohexene 3a quantitatively, as determined by 1 H NMR, and was isolated in 99% yield as a yellow solid.…”

Thermochemistry of alkaline-earth phenoxides

“…The values of thermochemical radii, OPh À , in alkaline-metal phenoxides were recalculations of data using auxiliary values [21]. Values of thermochemical radii, 2,6-Me 2 OPh À for alkaline-metal phenoxides were determined in a previous work [20].…”

“…15. The slope was taken from reference [21]; it was obtained by plotting d M-OC6H5 against (r + + r À ) data from alkaline phenoxide compounds. The second shell (Ca + Ca) is merely an assumption.…”

3 Alkali and alkaline-earth metals

“…10 The bonding energetics in a variety of alkali metal alkoxides and aryloxides have been determined using reaction-solution calorimetry and trends in the structureenergetics relationship, based on the Kapustinskii equation, were discussed. 11 The syntheses and unusual (in some cases unprecedented) structures of nine alkali metal amides derived from the [N(SiMe 2 Ph)(SiMe 3 )], [N(Bu t )(SiMe 3 )], [N(Ph)(2-C 5 H 4 N)] and [N(2-C 5 H 4 N) 2 ] anions have been reported. 12 A series of alkali metal 4-hydroxyphenolates and 1,4-phenylenediolates (hydroquinones) have been structurally characterized.…”