Structural studies of nonclassical cyclobutylmethyl cations by the ab initio method

High level ab initio calculations are used to obtain the structural information on primary, secondary and tertiary cyclobutylmethyl cations. The GIAO-CCSD(T) derived [super 13]C NMR chemical shifts of the selected carbocations are calculated to detect the nature and extent of charge delocalization into the cyclobutyl ring.