To evaluate the primary photoproducts obtained from the described N-haloamides, we pursued low-temperature photolyses of these compounds in frozen solvent matrices. Photolysis of a 2-Me-THF glass of 13a at 77 K resulted in the evolution of two new peaks in the UV-vis spectrum at 427 and 439 nm (Figure ). These peaks are well matched to spectral features of Mn(II) complex 15, which could be generated by photoreduction of 13a via Mn-N homolysis. To further confirm that the photolysis of 13a generates Mn(II)(TPP), we measured the X-band EPR at 4K and 9.35 GHz following irradiation of a 2-Me-THF glass of 13a at 77K (Figure ). Mn(III) complex 13a does not display an X-band EPR spectrum. Following photolysis, the measured spectrum exhibits features at g^ = 6 and g|| = 2, which are consistent with those of independently prepared Mn(II) complex 15 and are as expected for an axial S = 5/2 system with D >> hν. The differences in peak shape shown in Figure are due to differential axial ligation. Compound 15 is formed via photocleavage of the Mn-N bond and thus has no axial ligand, whereas independently synthesized 15 has an axial THF ligand. The observed EPR features were insensitive to the photolysis matrix: Photolysis of a solvent-free thin film of 13a resulted in the evolution of an EPR spectrum of 15 (Figure ). Low Temperature Photolysis of N-Iodoamide 13e. Photolysis of a 2-Me-THF glass of 13e at 77K results in the evolution of a new peak in the UV-vis spectrum at 441 nm, which is distinct from the spectrum observed from photolysis of 13a (Figure ). The X-band EPR spectrum of this sample measured at 4K and 9.35 GHz (Figure ) is significantly richer than that from the photolysis of 13a (Figure ). Features across the entire field range are observed, corresponding to g = 0.8, 1.2, 1.5, 2.0, 3.5, and 5.0. Such an EPR spectrum is inconsistent with either S = 3/2 or 5/2 with |D| >> hν. Rather, it can be simulated as an S = 5/2 complex with relatively small zfs (|D| = 0.18 cm -1 (5.4 GHz) and |E| = 0.0037 cm -1 ; |E/D| = 0.020). The spectral features of Mn(II) complex 15 are not observed in the spectrum obtained following photolysis of 13e, nor are features expected of a potential Mn(IV) complex with simple X-type axial ligands. Figure . Low-temperature (77K) photolysis of Mn(TPP)(NITs) (13e) results in N-I cleavage to generate Mn(IV) nitrenoid complex 20. (a) UV-vis spectra obtained periodically during the photolysis of 13e at 77K display wellanchored isosbestic points at 429, 449, 511 nm. (b) X-band EPR spectra following photolysis of a 2-Me-THF glass of 13e at 77K (¾). This spectrum was simulated with parameters D = 0.18 cm -1 and E = 0.0037 cm -1 (¾). *The peak at g = 2.0 has been truncated for clarity.