The formula for the calculation of the strain, the strain energy, and the angles of the bent bonds in small propellanes are proposed by using the ab initio program ABHF for calculating Hellmann-Feynman forces. The overlapping forces f0 and the corresponding equivalent point charges, the angle a of the bent bonds, the strain f0, the bonding force F and the strain energy d of the bent bonds of [1.1.1] propellane, [2.1.1] propellane, [2.2.1] propellane and [2.2.2] propellane were calculated The stabilities and the bonding behavior of these high strained mols. were also investigated. The theor. predictions are all in good agreement with the experimental results.

Key words: CHEMICAL BONDS, AB INITIO CALCULATION, MOLECULAR ORBITAL THEORY, BONDING, SPIRO COMPOUNDS, TENSION