Using the complete active space self-consistent field (CASSCF) method with 6-311++g(3df,3pd) basis sets, a few electronic states of nitrenes (CH3)(3)CN and (CH3)(2)CHN and their positive ions are calculated. All calculated states are valence states, and their characteristics are discussed in detail. In order to investigate the Jahn-Teller effect on (CH3)(3)CN radical, C-s symmetry was used for (CH3)(3)CN and (CH3)(2)CHN in the calculations. The results of our calculations (CASPT2 adiabatic excitation energies and RASSI oscillator strengths) suggest that the calculated transitions of (CH3)(3)CN at 27 710 cm(-1) and (CH3)(2)CHN at 28 110 cm(-1) are attributed to 2(3)A '' --> 1(3)A '', while those of (CH3)(3)CN at 28 916 cm(-1) and (CH3)(2)CHN at 29 316 cm(-1) are attributed to 1(3)A' --> 1(3)A ''. The vertical and adiabatic ionization energies were obtained to compare with the photoelectron spectroscopic data. These results are in agreement with previous experimental data. Also, we present a comprehensive review on the CAS calculation results for (CH3)(n)CH3-nN (n = 0-3) presented in our previous and present papers.