Relationships between basicity, structure, chemical shift and the charge distribution in resonance-stabilized iminoaminesElectronic supplementary information (ESI) available: energies and N⋯N distances in geometry-optimised iminoamine bases. See http://www.rsc.org/suppdata/p2/b2/b200899h/

Abstract

Taking formamidine (gas phase proton affinity ≈950 kJ mol Ϫ1 ) and guanidine (gas phase proton affintiy ≈990 kJ mol Ϫ1 ) as the prototype iminoamines with resonance-stabilized cations, similar non-cyclic analogs based on a conjugated carbon atom backbone are studied computationally. A simple model of the charge delocalization is developed which predicts theoretical maximum gas-phase proton affinties (PAs) of ≈1114 kJ mol Ϫ1 (unbranched), 1154 kJ mol Ϫ1 (singly-branched) and 1209 kJ mol Ϫ1 (doubly-branched) for such systems. It is also shown that the 1 H and 15 N chemical shifts of the protons and nitrogens in the imine functions correlate both with basicity and with atoms-in-molecules multipole moments. The properties of these and related compounds are discussed in the context of proton sponges or superbases.

Derivatives of Azacalix[3](2,6)pyridine are Strong Neutral Organic Superbases: A DFT Study

“…Design of neutral organic bases and superbases and their synthesis attracted a lot of attention and efforts recently − because they exhibit some advantageous features compared to their inorganic counterparts. − Various structural and electronic motifs have been used in tailoring strong and ultrastrong bases. The intramolecular hydrogen bonds (IMHBs) belong to the most important ones since the introduction of the first proton sponge, 1,8-bis(dimethylamino)naphthalene (DMAN) , 1 , depicted in Figure .…”