Reactivity of Lanthanoid Aryloxide Complexes: Isolation of a 1,2‐Dimethoxyethane Cleavage Product

[Yb(OAr)₂(μ‐OMe)(DME)]₂ ( 1 ) (OAr = 2,6‐di‐iso‐propylphenolate) was synthesised via a redox transmetallation ligand exchange reaction between ytterbium metal, diphenylmercury and 2,6‐di‐isopropylphenol in DME. The source of the methoxy groups is from cleavage of DME, and the C‐O bond activation is unexpected given that the reaction was undertaken at ambient temperature. Each Yb³⁺ metal ion in 1 is six coordinate, and the coordination arrangement around each metal ion is distorted trigonal antiprismatic with Yb‐O(OMe) bond lengths (2.191(2) and 2.258(2) Å) shorter than the Yb‐O(aryloxide) bond distances (2.094(2) and 2.074(2) Å).     

A sulphur dioxide adduct of triphenylindium

The product from the reaction of triphenylindium with sulphur dioxide, previously considered to be O-benzenesulphinatodiphenylindium(III), is now formulated as the $\text{1}\text{1}$ adduct, Ph₃In(O₂S).     

Chirality assignment of single-walled carbon nanotubes with strain

Strain-induced band gap shifts that depend strongly on the chiral angle have been observed by optical spectroscopy in single-walled carbon nanotubes (SWCNTs). Uniaxial and torsional strains are generated by changing the environment surrounding the SWCNTs, using the surrounding D2O ice temperature or the hydration state of a wrapping polymer. These methods are used as diagnostic tools to determine the quantum number q and examine chiral vector indices for specific nanotubes.     

Synthesis and Characterisation of Novel Bis(diphenylphosphane oxide)methanidoytterbium(III) Complexes

Reaction of [YbCp₂(dme)] (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (H₂dppmO₂) leads to deprotonation of the ligand H₂dppmO₂ and oxidation of ytterbium, forming an extremely air-sensitive product, [Yb^III(HdppmO₂)₃] (1), a six-coordinate complex with three chelating (OPCHPO) HdppmO₂ ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(C₆F₅)_2, and H₂dppmO₂. In a further preparation, the reaction of [Yb(C₆F₅)₂] with H₂dppmO₂, not only yielded compound 1, but also gave a remarkable tetranuclear cage, [Yb₄(µ-HdppmO₂)₆(µ-F)₆] (2) containing two [Yb(µ-F)]₂ rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmO₂ donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-H₂C₆F₄ and m-H₂C₆F₄, the last being an unexpected product.     

Transverse mode dynamics in a free-electron laser

We derive the most general equations of motion for the electrons and the electromagnetic field in a free-electron laser including the effects of diffraction and pulse propagation. The field evolution is expressed in terms of the amplitudes and phases of a complete set of transverse modes. The analytic solution is given in the small-signal regime, where the theory is shown to be in excellent agreement with a recent experiment at Orsay.     

Optical klystron experiments for the ACO storage ring Free Electron Laser

To improve the gain in the Orsay storage ring Free Electron Laser (FEL) experiment, the 17 period permanent magnet undulator has been modified to form an optical klystron (OK). We report the measurement of spontaneous emission and the effects on it of energy spread and angular spread. Gain and laser induced bunch lengthening measurements with the OK are also reported and are in very good agreement with the FEL classical theory. The spontaneous emission spectrum which is easy to measure with good signal to noise ratio, turns out to be a very good diagnostic tool forenergy spread and angular spread measurements on storage rings. The factor of four increase in the small gain obtained by converting the undulator NOEL into an OK was the critical factor in the recent operation of the ACO storage ring laser above threshold.     

Synthesis and Structures of Homoleptic Monomeric Potassium Aryloxolanthanoidate(III) Complexes

Reaction of lanthanoid tris(2, 6‐diphenylphenolates) [Ln(Odpp)₃] with KOdpp in 1, 2, 4, 5‐tetramethylbenzene (durene) at 200‐250 °C affords [K{Ln(OC₆H₃Ph₂‐2, 6)₄}], (Ln = La ( 1 ) or Nd ( 2 )) and 2 has also been obtained from the reaction of [Nd(Odpp)₃] with potassium hydride. In the solid state, 1 and 2 are monomeric bimetallics in which Ln is surrounded by a distorted tetrahedral array of oxygen atoms. Two Odpp ligands are oxygen bridged between K and Ln and also are η⁴‐Ph linked to potassium. One Odpp ligand bridges the metals in an O(Ln): η⁶‐Ph(K) manner that is new for lanthanoid complexes of this ligand, with no close K‐O contact, and the remaining Odpp is terminal on the Ln.