Abstract: Active radicals formed in the UVphotolysis of ferrocene and its amino-methyl substituted derivatives in CCl4 solution have been studied by means of spin trapp-ing-ESRtechnique. The results show that Ferrocene and substituted ferrocene are very sensitive to UVirradiation. As NDis used as trapping agent,the strong ESRsignals can be detected in photoreaction systems irradiated by UVfor only 1~3 min,but the strength of ESRsignals decay and disappear rapidly during less than 8 min and then the residual weak signal with 6 lines may be observed;when irradiation term is more than 3 min, noly 6 simple peaks may be observed.Therefore, The primary photolysis processes of ferrocene and its derivatives should produce free radicals(C₅H₅Fe)·, C₅H₅· and (C₅H₅Fe)·, (RC₅H₄)·, respectively. The active intermediate (C₅H₅Fe)· may be further decomposed to form C₅H₅· and Fe. The ESRspectrum with 25 linesmaybe is the signal of spin adducts (C₅H₅Fe-ND)·. The values of splitting con-stants for the spin adducts (RC₅H₄-ND)·, which may show ESRspectra with 6 lines, are nearly the same as for the spin adducts (C₅H₅-ND)·, then it can be concluded that the effect of substituent on the superfine splitting can't be observed. At the same time, three of the substituted ferrocenes can give out triplet ESRpeaks besides those 6 peaks, it means that there are two structural forms for spin adducts (RC₅H₄ND)·:

Key words: Ferrocene, Photolysis, Free radical, Spin trapping