Synthesis, Structure and Spectroscopic Properties of Lanthanide Complexes of N‐Confused Porphyrins

Abstract

AbstractA series of meso‐substituted N‐confused porphyrins (NCP) is synthesized using the modified Rothemund–Lindsey procedure. Lanthanide N‐confused porphyrinate complexes of the general formula [(NCP)Ln(LOMe)] [Ln3+ = Yb3+ and Er3+; L = (η5‐C5H5)Co{P(=O)(OMe)2}3–] are obtained in moderate yields upon interaction of N‐confused porphyrin free bases (H2NCP) with Ln[N(SiMe2)3]·x[LiCl(THF)3], followed by the addition of the tripodal anion L as an effective encapsulating agent for the lanthanide ions. The structural and spectroscopic data for these complexes provide evidence for an η2‐agostic interaction between the Ln3+ ion and the inner C–H bond of the NCP ligand. Methylation of [(NCTCPP)Yb(LOMe)] (H2NCTCPP = 2‐azo‐5,10,15,20‐tetracyanophenyl‐21‐carbaporphyrin) with methyl iodide yields the novel stable lanthanide complex of the N‐methylated derivative of N‐confused porphyrins, whose X‐ray structure also exhibits an η2‐agostic interaction between the metal center and the inner C–H bond of the NCTCPP ligand. The photophysical properties of the N‐confused porphyrins and their lanthanide complexes are investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)