engleski

The Proton Affinity of Some Extended pi-Systems Involving Guanidine and Cyclopropenimine Subunits

The proton affinity (PA) of some extended pi?electron systems involving guanidine and cyclopropeneimine structural motifs is explored by the theoretical MP2 and HF_SC models. It is shown that some of the studied molecules should exhibit higher gas phase basicity than Schwesinger proton sponge, which is considered to be one of the most powerful organic superbases. The origin of the increased basicity is traced down to a dramatic resonance effect triggered by the protonation. It is interesting to note that examined compounds possess higher PAs than their polyguanide counterparts. The reason behind it is a well established fact that the three?membered rings undergo aromaticization in the conjugate acids by forming aromatic moiety. The important role of substituents in determining high inherent basicities is underscored.

gas-phase basicities ; ab-initio ; electronic-structure ; aromatics ; molecules ; sponges ; bases ; OH

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