Basicity Bifurcated hydrogen bonds

The gas phase basicities and pKa values of tris(phosphazeno) substituted azacalix[3](2,6) pyridine in acetonitrile and some related compounds were examined by the density functional theory (DFT) computational method. It was shown that the hexakis(phospha-zeno) derivative of azacalx[3](2,6)pyridine is a hyperstrong neutral base, as evidenced by the absolute proton affinity of 314.6kcal/mol and pKa (MeCN) of 37.3 units. It is a consequence of the very strong bifurcated hydrogen bond (32kcal/mol) and substantial cationic resonance effect [14]. 

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