Hyperstrong neutral organic bases: phosphazeno azacalix[3](2,6)pyridines.
The gas-phase basicities and pKa values in acetonitrile of tris(phosphazeno)-substituted azacalix[3](2,6)pyridine and some related compounds are examined by DFT computational method. It is shown that the hexakis(phosphazeno) derivative of azacalix[3](2,6)pyridine is a hyperstrong neutral base as evidenced by the absolute proton affinity (APA) of 314.6 kcal mol(-1) and pKa(MeCN) of 37.3 units. It is a consequence of the very strong bifurcated hydrogen bond (32 kcal mol(-1)) and substantial cationic resonance effect.
Despotović
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Quantum Organic Chemistry Group, Department of Organic Chemistry and Biochemistry, The Ruder Bosković Institute, Zagreb, Croatia.
Kovacević
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Maksić
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ZB