This master thesis features the synthesis of (adamant-1-yl)phenyldiazomethane (1) and (adamant-2- yl)phenyldiazomethane (2) and investigation of their photophysical properties and photochemical reactivity. The photochemical reactivity was investigated by conducting photochemical reactions in cyclohexane, methanol and benzene solution upon excitation at 300 nm, which corresponds to the excitation to higher singlet excited state. Products of photochemical reactions were isolated and characterized by spectroscopic methods (1H and 13C NMR and MS). For compounds 1 and 2 we found out that they form products via singlet and triplet carbene intermediates. Furthermore, measurement of the quantum yields of the reaction upon excitation corresponding to S1 and Sn indicated that the compounds react from higher excited singlet states, contrary to the Kasha rule. Measurement of fluorescence for compounds 1 and 2 indicated that they deactivate by radiative transitions from higher singlet excited states, also contrary to the Kasha rule. The findings described in this thesis change the general paradigms of one of the fundamental organic chemical reaction, the photoelimination of nitrogen from diazoalkanes.