Synthesis of and Evidence for Electronic Communication within Heteromultimetallic Tetrakis(NCN-pincer metal)−(Metallo)porphyrin Hybrids

Several heteromultimetallic pincer−porphyrin hybrids have been prepared in excellent yields by stepwise metalation of a general precursor, [2H(Br(NCN))4], which was designed in such a way so as to guarantee selectivity for either the porphyrin or pincer sites during the metalation steps. First, a metal was introduced in the porphyrin cavity using a metal(II) salt, followed by metalation of the pincer units through oxidative addition to an appropriate metal(0) complex. The resulting multimetallic complexes show an appreciable amount of intramolecular communication between the meso-pincer metal groups and the central metalloporphyrin component. This was manifested in changes of the optical and ligand-binding properties of the metalloporphyrin part upon reactions at the peripheral pincer sites.