Synthesis and spectroscopic characterization of super-stable rhenium(V)porphyrins

The preparation of rhenium(V) porphyrin complexes {μ-oxo-bis[(oxo)(5,10,15,20-tetraphenyl-21H,23H-porphinato)rhenium(V)] [O ReTPP] 2 O ( 1 ), (oxo)(phenoxo)(2,3,7,8,12,13,17,18-octaethyl-5-monophenyl-21H,23H-porphinato)rhenium(V) O Re(PhO)MPOEP ( 2 ), (cloro)(oxo)(2,3,7,8,12,13,17,18-octaethyl-5,15-diphenyl-21H,23H-porphinato)rhenium(V) O Re(Cl) 5,15 DPOEP ( 4 ), and (oxo)(phenoxo)(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato)rhenium(V) O Re(PhO)OEP ( 5 )} by the interaction of H 2 ReCl 6 with corresponding porphyrin in boiling phenol is described. (Cloro)(oxo)(2,3,7,8,12,13,17,18-octaethyl-5-monophenyl-21H,23H-porphinato)rhenium(V) O Re(Cl)MPOEP ( 3 ) and (oxo)(chloro)(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato)rhenium(V) O Re(Cl)OEP ( 6 ) have been prepared by the reaction of axial-ligand substitution from ( 2 ) and ( 5 ), respectively. Compounds ( 2–4 ) were newly synthesized. Characterization of the compounds ( 1 – 6 ) reported herein was made mainly by UV–Visible, IR, 1 Н NMR, 1 H 1 H 2D COSY, 1 H 1 H 2D DOSY, 1 H 1 H 2D ROESY, 1 H 1 H 2D TOCSY spectroscopic techniques and elemental analysis. The stability of the complexes in solutions when exposed to strong acids at the presence of atmospheric oxygen has been estimated. Compounds ( 2–4 ) and ( 6 ) show them super-stable since they do not undergo dissociation along M N bonds in concentrated H 2 SO 4 under heating up to 363 K. Compounds ( 3 ) and ( 4 ) undergo one-electron oxidation to form stable π-cation radicals O Re ( HSO 4 ) P + under these conditions. The products of the reaction between all studied porphyrins and concentrated H 2 SO 4 were isolated in CHCl 3 by reprecipitation onto ice and proved to be rhenium(V) complexes O Re(HSO 4 )P.