The peripherally-molybdenated tetraphenylporphyrin complexes [5-{p-, m-, and o-[Mo(NO)Tp(*)Cl]OC6H4}-10,15,20-Ph(3)porphH(2)] (1-3, respectively; Tp(*) = [HB(3,5-Me(2)C(3)HN(2))(3)], tris(3,5-dimethylpyrazolyl)borate; Ph(3)-porphH(2) = triphenylporphyrin) and [5-{p-[Mo(NO)Tp(*)X]OC6H4}-10,15,20-Ph(3)porphH(2)] (X = OH, 4; X = I, 5), the metalloporphyrins [5-{p-[Mo(NO)Tp(*)X]OC6H4}-10,15,20-Ph(3)porphM] (M = Zn, 6; M = Ni, 7; M = Pt, 8), and the tetramolybdenated compound [5,10,15,20-{p-[Mo(NO)Tp*Cl]OC6H4}(4)porphH(2)] (9) have been prepared by reaction of the corresponding 5-(hydroxyphenyl)-10,15,20-triphenylporphyrin or 5,10,15,20-tetraphenylporphyrin derivative. Cyclic voltammetry shows that most of these complexes undergo two oxidation processes (associated with the porphyrin, internally-metalated or otherwise) and three reduction processes (two associated with the porphyrin and one with the molybdenum fragment). The redox potentials of the molybdenum fragment are little influenced by the presence of the macrocyclic ring, and vice versa. Preliminary photochemical measurements have been made on 1-3, which were found to undergo photoinduced intramolecular electron transfer, from the excited singlet state of the porphyrin macrocycle to the molybdenum moiety, yielding charge-separated states with lifetimes in the range 120-220 ps. Further studies, using spectroelectrochemistry and EPR spectroscopy, have been made to investigate the nature of the reduced molybdenum species. The molecular structures of 1 and 3 were determined crystallographically, and it was shown that the Mo-O(phenol) distances were relatively short [1.922(5) Angstrom for 1 and 1.855(23) Angstrom for 3], consistent with p(pi) --> d(pi) donation, and that in 3 one of the pyrrole rings of the porphyrin closely approaches one of pyrazolyl rings of the tris(3,5-dimethylpyrazolyl)borate ligand. This is consistent with H-1 NMR studies. The Mo-porphyrin centroid distances are 10.51 Angstrom in 1 and 6.69 Angstrom in 3.