Abstract: The UV spectra of p-NO₂-m-(SiMe_m-3)_n(SiMe₃)_nand m-NO₂-ph (SiMe_m-3) (SiMe₃)_msystems (m= 1, n=0,1,2; m=2n= 1) are analyzed by means of the EHMO-CI-SPIN-FREE method with four orbital model. The first, second and third absorpt on bands arise in essence from π→π^* transitions. Furthermore, the d atomic orbital of silicon chain may play an important role in the red shift of first absorption bands of p-NO₂-ph(SiMe_3-m)_n, (SiMe₃)_msystem. This can be considered due to two effects. One of them is the conjugation of d orbital (π_d(Si)) with π^*(ph) in LUMO. The other is the changing of electronic repulsion by changing d orbital and NO₂group components in LUMO.

Key words: Nitrophenylpo lysilanes, EHMO-Cl, d-Orbital (Si)