The dual role of Cu(i) as a protective group and a template in the synthesis of a tetra-rhodium(iii)porphyrin [2]catenane

Abstract

A new [2]catenane containing four Rh(III) porphyrins has been prepared following a three-step strategy: (i) Cu(I)-driven entwining of two free base porphyrin-bearing bidentate chelates, followed by (ii) insertion of rhodium in the porphyrin nuclei, and finally (iii) cyclisation via the formation of N–Rh coordination bonds. Direct metalation of porphyrinic compounds with [Rh(CO)₂Cl]₂ was not met with success when the bidentate chelate used as a connector was metal free, thus making the Cu(I) protecting approach very attractive.