Efficient blue-phosphorescent -bis(acyclic diaminocarbene) platinum(ii) acetylide complexes.

The lack of efficient and robust deep-blue phosphorescent metal complexes remains a significant challenge in the context of electroluminescent color displays. The emissive triplet states of blue phosphors are deactivated by low-lying metal-centered (MC) states, which can be ameliorated by increasing the σ-donating ability of the supporting ligands. Here we unveil a synthetic strategy to access blue-phosphorescent complexes with two supporting acyclic diaminocarbenes (ADCs), known to be even stronger σ-donors than N-heterocyclic carbenes (NHCs).

Platinum(II)-Substituted Phenylacetylide Complexes Supported by Acyclic Diaminocarbene Ligands.

We introduce phosphorescent platinum aryl acetylide complexes supported by -butyl-isocyanide and strongly σ-donating acyclic diaminocarbene (ADC) ligands. The precursor complexes -[Pt(CNBu)(C≡CAr)] () are treated with diethylamine, which undergoes nucleophilic addition with one of the isocyanides to form the -[Pt(CNBu)(ADC)(C≡CAr)] complexes (). The new compounds incorporate either electron-donating groups (4-OMe and 4-NMe) or electron-withdrawing groups [3,5-(OMe), 3,5-(CF), 4-CN, and 4-NO] on the aryl acetylide.

Stereoelectronic interactions: A booster for J transmission.

Long-range proton-fluorine coupling constants ( J ) are helpful for the structure elucidation of fluorinated molecules. However, their magnitude and sign can change with the relative position of coupled nuclei and the presence of substituents. Here, trans-4-tert-butyl-2-fluorocyclohexanone was used as a model compound for the study of the transmission of J .