Arylamidoethyl-Functionalized Imidazolium Salts: Precursors for Dianionic [ C, N, C]2a ' Carbene Carbene Ligands at a Platinum Center

Abstract

Arylamidoethyl-functionalized imidazolium bromides were prepared from the corresponding N-(2-bromoethyl)benzamides ArC(O)N(H)CH2CH2Br (Ar = 3-O2NC6H4, Ph, 3,4-Cl2C6H3) and 1-methylimidazole. These imidazolium salts react with PtCl2 in DMSO in the presence of a base at 100 °C to give ortho-metalated platinum(II) complexes, in which the imidazolium salt has lost a total of three protons. The resulting ligand is a tridentate, dianionic [C,N,C]2- pincer-type system, bound to the square-planar metal center through carbon atoms of the carbene and the ortho-metalated arene as well as the nitrogen atom of the amide functionality. The coordinated DMSO can be replaced by other N-heterocyclic carbenes, resulting in the formation of both homo- A nd heteroleptic bis(carbene) platinum(II) complexes. The molecular structures and photophysical properties of the complexes are reported. High-level computational methods were used to elucidate the electronic structures of the complexes.