Highly efficient ethylene polymerisation by scandium alkyls supported by neutral fac-kappa3 coordinated N3 donor ligands

Reaction of [M(CH2SiMe3)3(THF)2] (M = Sc or Y) with the neutral fac-kappa3 N3 donor ligands (L) Me3[9]aneN3 or HC(Me2pz)3 gave the corresponding trialkyls [M(L)(CH2SiMe3)3]; activation of the scandium congeners with B(C6F5)3 in the presence of ethylene afforded highly active polymerisation catalysts (Me3[9]aneN3 = 1,4,7-trimethyltriazacyclononane).     

The stereochemistry at silicon of an iron to cyclopentadienyl ligand silyl group migration in (η-C5H5)Fe(CO)2SiR3

The silyl group migration observed upon treating (R)(+)-(η⁵-C₅H₅)Fe(CO)₂-SiMePh(1-Np) with n-BuLi occurs with retention of configuration at silicon. The anion resulting from the migration, (η⁵-C₅H₄SiMePh(1-Np))Fe(CO)₂Li, is alkylated with MeI to give (R)-(−)-(η⁵-C₅H₄SiMePh(1-Np))Fe(CO)₂Me (II). Compound II is independently prepared from (η⁵-C₅H₅)Fe(CO)₂Me. A concerted mechanism for the migration involving frontside nucleophilic attack at silicon is suggested.     

The vibrations of formaldehyde

A new six-dimensional variational code is presented for the determination of the vibrational energy levels of four-atom molecules which are either linearly connected or centrally connected. Internal (displacement) coordinates are used. It is demonstrated for the CCSD(T) surface of formaldehyde, due to Martin, Lee and Taylor, and it is shown that a small scaling of the force constants leads to a high-accuracy surface.     

Partitioning of small amphiphiles at surfactant bilayer/water interfaces: an avoided level crossing muon spin resonance study

The temperature-dependent variation of local environment and reorientation dynamics of the small amphiphile 2-phenylethanol in lamellar phase dispersions of the dichain cationic surfactants, 2,3-diheptadecyl ester ethoxypropyl-1,1,1-trimethylammonium chloride (DHTAC) and dioctadecyldimethylammonium chloride (DODMAC), and the nonionic surfactant, tetra(ethylene glycol) n-dodecyl ether (C12E4), have been determined using avoided level crossing muon spin resonance spectroscopy (ALC-muSR). For cosurfactant radicals the hydrophobic or hydrophilic character of the surrounding media can be determined from their magnetic resonance signatures. Comparison of the three different bilayer-forming surfactant systems shows that the ALC-muSR technique is able to distinguish both major and subtle differences in the partitioning of the cosurfactant radicals between the different systems.     

Fast and slow lifetime degradation in boron‐doped Czochralski silicon described by a single defect

A demonstration that boron–oxygen related degradation in boron‐doped Czochralski silicon could be caused by a single defect with two trap energy levels is presented. In this work, the same two‐level defect can describe the fast and slow lifetime decay with a capture cross‐section ratio of electrons and holes for the donor level of σ_n/σ_p = 19 ± 4. A model is proposed for the multi‐stage degradation involving a single defect, in which the product of the slow reaction is a reactant in the fast reaction. After thermal processing, a population of interstitial oxygen (O_i) exists in a certain state (the precursor state) that can rapidly form defects (fast degradation) and another population of O_i exists in a state that is required to undergo a slow transformation into the precursor state before defect formation can proceed (slow degradation). Kinetic modelling is able to adequately reproduce the multi‐stage degradation for experimental data. Dark annealing is also shown to impact the extent of ‘fast’ degradation. By decreasing the dark annealing time on pre‐degraded wafers, a more severe ‘fast’ degradation of the samples can be enabled during subsequent illumination, consistent with this theory. The paper then discusses possible candidates for the chemical species involved. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Experimental and Computational Studies of the Copper Borate Complexes [(NHC)Cu(HBEt3)] and [(NHC)Cu(HB(C6F5)3)]

The synthesis of the Cu‐borate complexes [(6Mes)Cu(HBR₃)] featuring the unusual [HBEt₃]^? ( 5 ) and [HB(C₆F₅)₃]^? ( 6 ) ligands is described. Experimental and computational studies show both compounds feature a direct Cu–H interaction, but that while 5 is two‐coordinate, 6 displays an additional, stabilizing Cu–C_ipso(C₆F₅) interaction.     

Unprecedented steric deformation of ortho-carborane

The reduction and subsequent oxidation of meta-carboranes containing bulky groups attached to the cage C atoms affords sterically-crowded ortho-carboranes with unprecedentedly long C-C connectivities.     

Unusual parallel and inclined interlocking modes in polyrotaxane-like metal-organic frameworks

We describe here two unusual polyrotaxane-like metal-organic frameworks of [Co2(1,3-bix)2(bpea)2] and [Cd4(1,4-bix)4(bpea)4] x 4H2O , where both species contain loops and rods that are interlaced in a highly rare "parallel" fashion in , but, uniquely, in an "inclined" fashion in .     

Biotemplated synthesis of an ordered macroporous superconductor with high critical current density using a cuttlebone template

Periodic superconducting, porous self-supporting monoliths were synthesized using cuttlebone as a morphological template; this produced a lightweight, structurally stable superconductor with a greatly improved critical current density.     

TG-MS analysis of the thermal decomposition of pig bone for forensic applications

In order to investigate the potential of thermal analysis for the determination of post-mortem age, rib bone specimens were collected from the remains of a number of slaughtered pigs that were allowed to decompose in the Australian bush in a controlled site under a range of conditions for time periods ranging from 1 to 5 years. The bone specimens were cut in cross-section with the compact bone collected for analysis. TG-MS curves were collected by heating bone samples to 1100°C in an argon atmosphere. The TG-MS data showed significant differences for the pig bone specimens derived from the different environments and showed trends in peak size correlating with age. The reported data suggest that TG-MS has significant potential for the identification of origin as well as the ageing of skeletal remains in a forensic context.