Divergent Behavior of Palladium(II) and Platinum(II) in the Metalation of 1,3-Di(2-pyridyl)benzene

Abstract

1,3-Di(2-pyridyl)benzene undergoes regioselective orthometalation with Pd(OAc)2 on the central aryl ring, giving rise to a dimeric complex in which four acetate units act as bridges between two doubly metalated ligands and each pyridine ligand coordinates to a different metal atom. The reaction with chloride-containing Pd(II) complexes does not lead to C−H activation but to coordination complexes without Pd−C bonds. Cycloplatination of 1,3-di(2-pyridyl)benzene takes place at C-2 of the benzene ring, generating a terdentate ligand. This behavior is the same as that previously observed for Ru and Os. Both orthometalated complexes have been structurally characterized by X-ray diffraction.

N∧C∧N‐Coordinated Platinum(II) Complexes as Phosphorescent Emitters in High‐Performance Organic Light‐Emitting Devices

“…All materials were used as supplied. The synthesis of the ligands and their platinum(II) complexes has been described previously [18,19,33]. However, for the present work, the mesityl ligand HL 6 was prepared differently, as described below.…”

Cyclometallated nitrogen heterocycles

“…By analogy with the work of others [10,28,29] these compounds are assumed to be dimers. These dimers were characterised by solution NMR and then cleaved by reaction with sodium acetylacetonate in tetrahydrofuran to give the monomeric compound 12.…”

Photoluminescent properties of heteroleptic cyclometalated platinum(II) complexes bearing 1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dionate as an ancillary ligand

“…For OLED application, cyclometalated iridium(III) complexes involving homoleptic Ir(C 4 N) 3 and heteroleptic (C 4 N) 2 Ir(O 4 O) complexes have been widely studied (C 4 N and O 4 O are 2-arylpyridinate and 1,3-diketonate ligands, respectively) [8,9]. Their phosphorescent properties arise from a strong spinorbit coupling (the heavy metal effect) as well as an increase in the d-d* energy states due to the strong ligand field of C 4 N. Cyclometalated platinum(II) complexes are also good phosphorescent materials, as represented by heteroleptic (C 4 N)Pt(O 4 O) complexes [10], homo-and heteroleptic (C 4 N)Pt(C 4 N) complexes [11,12], tridentate (N 4 C 4 N)PtX complexes (X; anionic ligand) [13][14][15], and others. Among these, heteroleptic (C 4 N)Pt(O 4 O) complexes developed by Thompson and coworkers (Fig.…”