An unusual cationic Ru(II) indenylidene complex and its Ru(III) derivative--efficient catalysts for high temperature olefin metathesis reactions

The use of a mixed phosphite/N-heterocyclic carbene bearing ruthenium precursor permits the synthesis and characterisation of unprecedented four-coordinate Ru(II) and Ru(III) cationic complexes adopting an unusual sawhorse structure. The cationic Ru(II) complex performs very effectively on challenging substrates at high temperature in very short reaction times and low catalyst loadings.     

Synthesis and characterisation of four- and six-membered P-Se heterocycles

The preparation, spectroscopic characterisation and crystal structures of [FcP(mu-Se)Se]2, [FcP(mu-Se2)Se]2 and [PhP(mu-Se2)Se]2 are reported. Crystallographic data reveal planar four-membered PSePSe and skewed six-membered P2Se4 rings, respectively, in all cases with trans arrangement of organic substituents and exo selenium atoms. Whilst stable at room temperature in solid state, NMR data suggest the six-membered rings of both the ferrocenyl and phenyl compounds decompose in the solution with loss of red selenium, forming PSe2PSe five-membered rings.     

Crystal structures of dibenzo[ce]‐1,2‐dithiine and its related oxides

The X‐ray structures of dibenzo[ce]‐1,2‐dithiine, dibenzo[ce]‐1,2‐dithiine‐5,5‐dioxide, diben‐ zo[ce]‐1,2‐dithiine‐5,5,6‐trioxide, and dibenzo[ce]‐1, 2‐dithiine‐5,5,6,6‐tetraoxide are reported and compared with the related “constrained'' naphthalene deri‐ vatives. The S‐S distances vary upon oxidation of the S centers in the order S‐S < SO‐S > SO₂‐S < SO₂‐SO > SO₂‐SO₂ i.e. the most oxidized sulfur atoms do not lead to the longest bond lengths. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:346–351, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20101     

Synthetic and Structural Study of peri-Substituted Phosphine-Arsines

A series of phosphorus-arsenic peri-substituted acenaphthene species have been isolated and fully characterised, including single crystal X-ray diffraction. Reactions of EBr₃ (E = P, As) with iPr₂PAcenapLi (Acenap = acenaphthene-5,6-diyl) afforded the thermally stable peri-substitution supported donor–acceptor complexes, iPr₂PAcenapEBr₂ 3 and 4. Both complexes show a strong P→E dative interaction, as observed by X-ray crystallography and ³¹P NMR spectroscopy. DFT calculations indicated the unusual As∙∙∙As contact (3.50 Å) observed in the solid state structure of 4 results from dispersion forces rather than metallic interactions. Incorporation of the excess AsBr₃ in the crystal structure of 3 promotes the formation of the ion separated species [iPr₂PAcenapAsBr]⁺Br⁻ 5. A decomposition product 6 containing the rare [As₆Br₈]^2– heterocubane dianion was isolated and characterised crystallographically. The reaction between iPr₂PAcenapLi and EtAsI₂ afforded tertiary arsine (BrAcenap)₂AsEt 7, which was subsequently lithiated and reacted with PhPCl₂ and Ph₂PCl to afford cyclic PhP(Acenap)₂AsEt 8 and acyclic EtAs(AcenapPPh₂)₂ 9.     

A Deep-Blue-Emitting Heteroatom-Doped MR-TADF Nonacene for High-Performance Organic Light-Emitting Diodes**

We present a p- and n-doped nonacene compound, NOBNacene, that represents a rare example of a linearly extended ladder-type multiresonant thermally activated delayed fluorescence (MR-TADF) emitter. This compound shows efficient narrow deep blue emission, with a λ_PL of 410 nm, full width at half maximum, FWHM, of 38 nm, photoluminescence quantum yield, Φ_PL of 71 %, and a delayed lifetime, τ_d of 1.18 ms in 1.5 wt % TSPO1 thin film. The organic light-emitting diode (OLED) using this compound as the emitter shows a comparable electroluminescence spectrum peaked at 409 nm (FWHM=37 nm) and a maximum external quantum efficiency (EQE_max) of 8.5 % at Commission Internationale de l’Éclairage (CIE) coordinates of (0.173, 0.055). The EQE_max values were increased to 11.2 % at 3 wt % doping of the emitter within the emissive layer of the device. At this concentration, the electroluminescence spectrum broadened slightly, leading to CIE coordinates of (0.176, 0.068).