Primary amido substituted diborane4 compounds and imidodiborate4 anions

Treatment of the diborane(4) compound B(2)(NMe(2))(4) with aniline or 2,6-dimethylaniline results in the primary amido compounds B(2)(NHR)(4)(R = Ph, 2,6-Me(2)C(6)H(3)); subsequent treatment with n-BuLi in toluene in each case affords the first examples of anionic imidodiborates namely Li(4)(thf)(6)B(2)(NPh)(4) and Li(4)(thf)(4)B(2)(N-2,6-Me(2)C(6)H(3))(4); all complexes have been characterised crystallographically.     

Correlation between the superconducting transition temperature and anisotropic quasiparticle scattering in Tl2Ba2CuO6+delta

Angle-dependent magnetoresistance measurements are used to determine the isotropic and anisotropic components of the transport scattering rate in overdoped Tl2Ba2CuO6+delta for a range of Tc values between 15 and 35 K. The size of the anisotropic scattering term is found to scale linearly with Tc, establishing a link between the superconducting and normal state physics. A comparison with results from angle resolved photoemission spectroscopy indicates that the transport and quasiparticle lifetimes are distinct.     

Lifetimes of high-spin yrast states in 154Er

Lifetimes for high-spin levels (between about 10 and 30 ?) in ¹⁵⁴Er have been measured by the recoil-distance method. Non-collective, moderately collective and collective E2 transitions from states with lifetimes between at most 10 and 400 ps have been found. All available data on this nucleus are discussed within the framework of the oblate coupling scheme with the addition of collective degrees of freedom.     

A simple entry into nido-C2B10 clusters: HCl promoted cleavage of the C-C bond in ortho-carboranyl diphosphines

Treatment of the diphosphines ortho-B10H10C(P(t)Bu2)C(PR2) (R = Et, Cy, Ph) with HCl gives the zwitterionic, nido-12-vertex species B10H10C(PH(t)Bu2)C(PClR2); these reactions are reversed by the addition of NEt3.     

Intramolecular direct arylation in the synthesis of fluorinated carbazoles

The amination of 2-chloroanilines with aryl bromides and subsequent intramolecular direct arylation can be exploited in the synthesis of a range of fluorinated carbazoles, where the fluorine substituent can be introduced via the aniline, the aryl bromide or both substrates. Depending on substitution patterns, the two steps can either be performed in tandem in one-pot under microwave heating conditions or else require a two pot approach.     

1H NMR direct observation of enantiomeric exchange in palladium(II) and platinum(II) complexes containing N,N' bidentate aryl-pyridin-2-ylmethyl-amine ligands

The complexes [MCl(2)(kappa2-N approximately N')] (N approximately N' = 2-C(5)H(4)N-CH2-NHAr; Ar = 4-MeC(6)H(4), a; 2,6-Me(2)C(6)H(3), b; 4-MeOC(6)H(4), c; 4-CF(3)C(6)H(4), d; M = Pd, 1a-d; Pt, 2a-d) have been prepared and fully stereochemically characterized both in the solid state and in solution. Their behavior in DMSO-d6 solution is dependent on the substituents of the aryl group and on the metal. Complexes of palladium with substituents at the para position (1a, 1c, 1d) display a dynamic 1H NMR pattern when the solutions are heated. An enantiomeric exchange Slambda/Rdelta is suggested to explain such behavior. On the basis of the calculated negative DeltaS values, an associative mechanism involving the solvent is proposed. Under the same conditions, analogous complexes of platinum (2a, 2c, 2d) proved to be unstable, and release of the N approximately N' ligand was observed. Complexes 1b and 2b show temperature-variable 1H NMR spectra without any evidence accounting for enantiomeric exchange or decoordination. DFT calculations on models of 1a and 1b show that diastereomeric exchange Sdelta/Slambda is a process where the complex with the higher sterical hindrance, 1b, has a lower energy barrier.