Phosphorescent Thiazol-2-ylidene Platinum(II) Complexes with β-Ketoiminates: Single Isomer Formation by Ligand Architecture

We present the synthesis and photophysical properties of six. novel N-phenyl-1,3-thiazol-2-ylidene platinum(II) complexes with sterically demanding N-aryl-beta-ketoiminate ligands. Diverse aryl substituents at the coordinating nitrogen atom (phenyl, mesityl, 2,6-diisopropylphenyl, 4-cyanophenyl, 1-naphthyl, and 2,4-difluorophenyl) of the N-aryl-(3Z)-4-amino-3-penten-2-ones exclusively yielded the SP 4-3 coordinated (CC)-C-boolean AND* cyclometalated platinum(II) complexes as single isomers as a consequence of the low steric demand of the (CC)-C-boolean AND* cyclometalating thiazole ligand and the bulkiness of the beta-ketoiminate ligands. The formation of this isomer was confirmed by Pt-195 NMR and extensive 2D NMR experiments, two solid-state structures, and the results of DFT calculations. As a proof of principle, two complexes with the sterically less demanding beta-ketoiminate ligands (3Z)-4-amino-3-penten-2-onato and (2Z)-3-amino-1-phenyl-2-buten-1-onato were synthesized and isolated as an isomeric mixture.