The ultraviolet photoelectron spectroscopy (UPS) of 6 boratranes are recorded.The configurations of the molecules are optimized at RHF/3- 21G level.theassignment of the UPS bands has also been done with the aid of the band shape and RHF/6-31GA^* calculation, the bands of σN- B electrons of the compounds are located accurately.the topological analysis of the electronic charge density of the compounds shows that the boron atoms are with relatively positive ion characters, and there exists a bond critical point between N and B,which suggests the existence of a B--N bond in these compounds .The bond of N--B is weakened by the addition of the CH3 and CH2,and is strengthened by of the addition of C==O.The above substitution effect is xonfirmed by UPS, SCF MO calculations and electron charge density topological analysis.

Key words: NITROGEN HETEROCYCLICS, BORON HETEROCYCLIC COMPOUNDS, TRICYCLIC COMPOUND, CHEMICAL BONDS, TOPOLOGY, ELECTRON DENSITY