Platinum(II) Monomer and Dimer Complexes with a Bis(oxazolinyl)phenyl Pincer Ligand

Abstract

A series of platinum(II) complexes with the formulas Pt(phebox)(L)(+) (phebox(-) = 1,3-bis(4,4'-dimethyl-2'-oxazolinyl)phenyl anion; L = pyridine (py), 4-phenylpyridine, quinoline, acridine) and Pt2(phebox)2(μ-L')(2+) (L' = pyrazine, 4,4'-bipyridine, 1,2-bis(4-pyridyl)ethane) was prepared. Crystallographic data establish that the metal center is bonded to the tridentate phebox(-) and monodentate pyridyl ligands. The five-membered oxazoline rings favor a CH2-CMe2 twist conformation. Pt(phebox)Cl and Pt(phebox)(py)(+) undergo a ligand-based chemically reversible redox reaction, whereas the electrochemistry of the other complexes is chemically and electrochemically less reversible. In contrast to complexes with the 1,3-bis(piperdylmethyl)phenyl anion ligand (pip2NCN(-)) or related pincer ligands, each of the phebox(-) complexes described here exhibits intense emission in room-temperature methylene chloride solution, which is assigned as originating from a lowest, predominantly phebox(-) ligand-centered excited state. In acetonitrile, the complexes undergo solvolysis resulting in displacement of the pyridyl ligands. The accumulated data demonstrate that subtle variations in the nature of the NCN and ancillary ligands of platinum(II) complexes provide access to at least five orbitally distinct emissive excited states.

Strong red emissions induced by Pt–Pt interactions in binuclear cycloplatinated(II) complexes containing bridging diphosphines

“…The luminescence properties of the cyclometalated platinum(II) complexes make them appropriate candidates for investigation by many research groups . Regarding these properties, cycloplatinated(II) complexes have various applications such as in light‐emitting devices, dye‐sensitized solar cells, photoswitches, photocatalysts and chemical or biochemical sensors .…”

Luminescent mononuclear and dinuclear cycloplatinated (II) complexes comprising azide and phosphine ancillary ligands

“…In the last decade, the luminescence properties of cycloplatinated (II) complexes have always been important subjects in many outstanding research groups . Room temperature phosphorescence in these complexes requires a chromophoric cyclometalated ligand and a Pt atom which is able to allow singlet–triplet intersystem crossing due to its high spin–orbit coupling constant.…”

Regiospecific Remote Pt–H Interactions in Oligomethylene‐Vaulted (N^C^N)‐Pincer PtII Complexes

“…However, there have been no such reports, because most conventional vaulted complexes have been designed to be as rigid as possible for synthetic and functional reasons, which has probably led to this chemistry being unascertained up to now. As a part of a program aimed at the development of new functional materials based on controlled d–π conjugation platforms bearing three‐dimensional overall structures,, , we have found that novel polymethylene‐vaulted Pt complexes bearing ( N ^ C ^ N ) tridentate cyclometallating ligands ( 1 and 2 ) undergo remote hydrogen bonding to form intramolecular M–H interactions between Pt atom and linker hydrogens, where the regiospecificity of the interactions in long alkyl chains is altered upon variation of the linker length (Scheme ). In this paper, we report the synthesis, structure and conformational study of complex 1 and 2 with a focus on the structure‐dependence of the Pt–H interactions as a key factor for conformational fixation of the vaulted complexes.…”

“…ArH24,26 ), 7.09 (t, J = 7.5 Hz, 1 H, ArH 4 ), 7.36(d, J = 8.6 Hz, 2 H, ArH23,27 ), 7.49(d, J = 7.5 Hz, 2 H, ArH 3,5 ),8.41 [(66 %) s, (34 %) d, 3 J PtH = 131.3 Hz, 2 H, N=CH7,8 ] ppm 13. C NMR (125 MHz, CDCl 3 ): δ = 21.…”