Synthesis and Electrochemical Studies of Porphyrin Dimers Linked by Metallocarbenes

The functionalization of porphyrins at the meso positions by azoles led, after subsequent alkylation, to several precursors of N-heterocyclic carbenes. Porphyrin dimers linked by palladium (or rhodium) bis-carbene spacers were prepared and characterized. Spectroscopic data and X-ray structures showed that the coordination geometry for the two carbenes around the palladium linker was trans-anti. Electrochemical studies revealed significant electronic communication between the two porphyrins, despite the absence of conjugation pathways.