Luminescent Anionic Cyclometalated Organoplatinum (II) Complexes with Terminal and Bridging Cyanide Ligand: Structural and Photophysical Properties
Mina Sadeghian, David Gómez de Segura, Mohsen Golbon Haghighi, Nasser Safari, Elena Lalinde, M. Teresa Moreno
Abstract
High Resolution Image Download MS PowerPoint Slide We present the synthesis and characterization of two series of mononuclear heteroleptic anionic cycloplatinated(II) complexes featuring terminal cyanide ligand Q + [Pt(C^N)( p -MeC 6 H 4 )(CN)] − [C^N = benzoquinolate (bzq), Q + = K + 1 and NBu 4 + 4; 2-phenylpyridinate (ppy), Q + = K + 2 and NBu 4 + 5 and 2-(2,4- difluorophenyl)pyridinate (dfppy), Q + = K + 3 and NBu 4 + 6 ] and a series of symmetrical binuclear complexes (NBu 4 )[Pt 2 (C^N) 2 ( p -MeC 6 H 4 ) 2 (μ-CN)] (C^N = bzq 7, ppy 8, dfppy 9 ). Compounds 5, 6, and 7 – 9 were further determined by single-crystal X-ray diffraction. There are no apparent intermolecular Pt···Pt interactions owing to the presence of bulky NBu 4 + counterion. Slow crystallization of K[Pt(ppy)( p -MeC 6 H 4 )(CN)] 2 in acetone/hexane evolves with formation of yellow crystals, which were identified by single-crystal X-ray diffraction methods as the salt complex {[Pt(ppy)( p -MeC 6 H 4 )(CN)] 2 K 3 (OCMe 2 ) 4 (μ-OCMe 2 ) 2 }[Pt(ppy)( p -MeC 6 H 4 )(μ-CN)Pt(ppy)( p -MeC 6 H 4 )]·2acetone ( 10 ), featuring the binuclear anionic unit 8 – neutralized by an hybrid inorganic–organometallic coordination polymer {[Pt(ppy)( p -MeC 6 H 4 )(CN)] 2 K 3 (OCMe 2 ) 4 (μ-OCMe 2 ) 2 } + . The photophysical properties of all compounds were recorded in powder, polystyrene film, and solution states with a quantum yield up to 21% for 9 in the solid state. All complexes displayed bright emission in rigid media, and for the interpretation of their absorption and emission properties, density functional theory (DFT) and time-dependent DFT calculations were applied.