1. Organometallic Intermediates in the Synthesis of Photoluminescent Zirconium and Hafnium Complexes with Pyridine Dipyrrolide Ligands.
- Author
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Leary DC, Zhang Y, Rodriguez JG, Akhmedov NG, Petersen JL, Dolinar BS, and Milsmann C
- Abstract
The two commercially available zirconium complexes tetrakis(dimethylamido)zirconium, Zr(NMe
2 )4 , and tetrabenzylzirconium, ZrBn4 , were investigated for their utility as starting materials in the synthesis of bis(pyridine dipyrrolide)zirconium photosensitizers, Zr(PDP)2 . Reaction with one equivalent of the ligand precursor 2,6-bis(5-methyl-3-phenyl-1 H -pyrrol-2-yl)pyridine, H2 Me PDPPh , resulted in the isolation and structural characterization of the complexes (Me PDPPh )Zr(NMe2 )2 thf and (Me PDPPh )ZrBn2 , which could be converted to the desired photosensitizer Zr(Me PDPPh )2 upon addition of a second equivalent of H2 Me PDPPh . Using the more sterically encumbered ligand precursor 2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1 H -pyrrol-2-yl)pyridine, H2 Mes PDPPh , only ZrBn4 yielded the desired bis-ligand complex Zr(Mes PDPPh )2 . Careful monitoring of the reaction at different temperatures revealed the importance of the organometallic intermediate (cyclo-Mes PDPPh )ZrBn, which was characterized by X-ray diffraction analysis and1 H NMR spectroscopy and shown to contain a cyclometalatedMes PDPPh unit. Taking inspiration from the results for zirconium, syntheses for two hafnium photosensitizers, Hf(Me PDPPh )2 and Hf(Mes PDPPh )2 , were established and shown to proceed through similar intermediates starting from tetrabenzylhafnium, HfBn4 . Initial studies of the photophysical properties of the photoluminescent hafnium complexes indicate similar optical properties compared to their zirconium analogues., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)- Published
- 2023
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