CONVERGENT AND DIVERGENT NONCOVALENT SYNTHESIS OF METALLODENDRIMERS

A new building block is constructed with one pyridine and two kinetica lly inert complexed Pd(II) ions, for the controlled assembly of metall odendrimers following either a convergent or a divergent route. The do uble pincer ligand 8 was cyclopalladated with Pd[CH3CN](4)(BF4)(2) and subsequently converted into the neutral bis-palladium chloride comple x 3. The pyridine moiety of 3, that is covalently attached to the spac er bridging the two pincer complexes, coordinates to activated palladi um centers. Via a combination of pyridine(3) and cyano-based (2) build ing blocks, dendrons up to generation three were assembled and charact erized with H-1 NMR and FT-W spectroscopy and MALDI-TOF mass spectrome try. These dendrons can coordinate through a cyano Ligand to an activa ted nucleus 1 forming convergently assembled metallodendrimers. Altern atively, building blacks 3 were used in the divergent assembly of more stable metallodendrimers, because of the stronger coordination of pyr idine compared to cyano ligands. The formation of metallodendrimers is evidenced by IR and H-1 NMR spectroscopy and electro spray and MALDI- TOF mass spectrometry.