Correlation between proton affinity and conjugation effects in carbamic acid and its higher chalcogenide analogs

The protonation sites and conformations of N-substituted and Y-substituted carbamic acid have been investigated. The proton affinities of substituted carbamic acid for their chalcogen and nitrogen sites have been evaluated theoretically at the MP2/6-311++G(d,p)//MP2/6-31+G∗ and B3LYP/6-311++G(d,p)//B3LYP/6-31+G∗ levels. Proton affinity have been correlated with the several contributing factors like charge density, percentage s character and conjugative interactions.