The intramolecular hypervalent interaction between the electron abundant atomic centers X and Y belonging to the IV-VI groups and second and fourth periods has been computationally studied on a model quasi-cyclic conjugate five-membered ring system 9 using the CCSD/6-311+G** and DFT B3LYP/6-311+G** methods. Electronic and structural factors affecting the strength and geometrical characteristics of the hypervalent X-Y interaction were analyzed based on the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The donor-acceptor n(Y)->sigma*(XR) interaction has been shown to be the central factor correlating all important properties of the studied hypervalently bonded compounds 9.