Syntheses, Structures, and Electronic and Photophysical Properties of Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes Derived from (C6F5)(R3P)2Pt, (p-tol)(R3P)2Pt, and (Ph3P)Au End-Groups

High-Purity and Saturated Deep-Blue Luminescence from trans-NHC Platinum(II) Butadiyne Complexes: Properties and Organic Light Emitting Diode Application

Two new platinum(II) compounds with trans-(NHC)₂Pt(C≡C-C≡C-R)₂ (where NHC = N-heterocyclic carbene and R = phenyl or trimethylsilyl) architecture exhibit sharp blue-green or saturated deep-blue phosphorescence with high color purity. The photoluminescence of both compounds is dominated by an intense 0-0 band with distinct but weaker vibronic progressions in both tetrahydrofuran (THF) and poly(methyl methacrylate) (PMMA) matrix. The full width at half-maximum (fwhm) of the photoluminescence of trans-(NHC)₂Pt(C≡C-C≡C-trimethylsilyl)₂ are 10 nm at room temperature and 4 nm at 77 K, while the trans-(NHC)₂Pt(C≡C-C≡C-phenyl)₂ shows a fwhm of 14 nm at room temperature and 8 nm at 77 K. The Commission International de L'Eclairage (CIE) coordinates of trans-(NHC)₂Pt(C≡C-C≡C-phenyl)₂ are (0.222, 0.429) in PMMA, and trans-(NHC)₂Pt(C≡C-C≡C-trimethylsilyl)₂ has a deep-blue CIE of (0.163, 0.077) in PMMA. When doped into PMMA, the phosphorescence quantum yield of the complex with trimethylsilyl-butadiyne ligand increases dramatically to 57% from 0.25% in THF, while the complex with phenyl-butadiyne ligand has similar quantum yields in PMMA (32%) and THF (37%). Organic light-emitting diodes (OLEDs) employing these two complexes as the emitters were successfully fabricated with electroluminescence that closely matches the corresponding photoluminescence. The OLEDs based on trans-(NHC)₂Pt(C≡C-C≡C-trimethylsilyl)₂ display highly pure deep-blue electroluminescence (fwhm = 12 nm) with CIE coordinates of (0.172, 0.086), approaching the most stringent National Television System Committee (NTSC) coordinates for "pure" blue of (0.14, 0.08).

Metal coordination to a dimetallaoctatetrayne

The reactions of the ditungstaoctatetrayne [(Tp*)(CO)₂W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash])W(CO)₂(Tp*)] with several metal complexes have been investigated. Addition of [Co₂(CO)₈] occurs across the internal C[triple bond, length as m-dash]C bonds, whereas [AuCl(SMe₂)] initially delivers 'AuCl' across the W[triple bond, length as m-dash]C carbyne bonds before undergoing further reaction to oxidise the tungsten and replace the carbonyl ligands with chloride in [(Tp*)Cl₂W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash])WCl₂(Tp*)] with retention of the ditungstaoctatetrayne bridge. Reaction with [AuCl(PR₃)] (R = Ph, Cy) in the presence of AgPF₆ prevents this oxidation and adds [AuPR₃]⁺ across the W[triple bond, length as m-dash]C bonds to give dicationic derivatives. Finally, the reaction with [Pt(nbe)₃] (nbe = norbornene, bicyclo[2.2.1]hept-2-ene) and 1,5-cyclooctadiene (COD) adds a 'Pt(COD)' unit to one or both tungsten-carbon bonds, allowing both the mono- and diplatinum complexes to be isolated.