Suzuki-Miyaura, alpha-ketone arylation and dehalogenation reactions catalyzed by a versatile N-heterocyclic carbene-palladacycle complex

[reaction: see text] The activity of the complex (IPr)PdCl(eta2-N,C-C12H7NMe2), 1 [IPr = (N,N'-bis(2,6-diisopropylphenyl)imidazol)-2-ylidene], in the Suzuki-Miyaura cross-coupling reaction involving unactivated aryl chlorides and triflates with arylboronic acids at room temperature in technical grade 2-propanol is described. These conditions allow for the synthesis of di- and tri-ortho-substituted biaryls in very short reaction times. This complex also displays very high activity for alpha-ketone arylation and dehalogenation reactions of activated and unactivated aryl chlorides.     

Synthetic routes to [Au(NHC)(OH)] (NHC = N-heterocyclic carbene) complexes

New procedures for the synthesis of [Au(NHC)(OH)] are reported. Initially, a two-step reaction via the digold complex [{Au(NHC)}(2)(μ-OH)][BF(4)] was probed, enabling the preparation of the novel [Au(SIPr)(OH)] complex and of its previously reported congener [Au(IPr)(OH)]. After further optimization, a one-step procedure was developed.     

Four-quasiparticle high-K band in 130Ce

High-spin states have been populated in ¹³⁰Ce, using the ¹⁰⁰Mo(³⁴S, 4n??) reaction at 155 MeV. A new strongly coupled structure has been found and is interpreted as based on a mixed neutron-proton high-K four-quasiparticle configuration.     

A simple method using on-line continuous leaching and ion exchange chromatography coupled to inductively coupled plasma mass spectrometry for the speciation analysis of bio-accessible arsenic in rice

A simple method for the speciation analysis of bio-accessible arsenic (As) in rice was developed using a continuous on-line leaching method to release the bio-accessible fraction. The continuous on-line leaching method has several advantages over commonly used batch methods including quicker and easier sample preparation, reduced risk of contamination and access to real time leaching data. The bio-accessibility of As in the samples was monitored using inductively coupled plasma mass spectrometry (ICP-MS). Results from a certified reference material as well as cooked and uncooked white rice showed that the majority of As was leached by saliva. Results obtained using the continuous on-line leaching method were comparable to those obtained using a batch method. Speciation analysis of the saliva leachate was performed using ion exchange chromatography coupled to ICP-MS. The four most toxic forms of As (As(III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and As(V)) were clearly separated within 5 min in a single chromatographic run. Over 92% of bio-accessible As in the certified reference material and uncooked white rice sample was in the form of DMA and As(V), whereas it was present as DMA and As(III) in the cooked white rice.     

Simple Synthetic Routes to N-Heterocyclic Carbene Gold(I)–Aryl Complexes: Expanded Scope and Reactivity

The discovery of sustainable and scalable synthetic protocols leading to gold–aryl compounds bearing N-heterocyclic carbene (NHC) ligands sparked an investigation of their reactivity and potential utility as organometallic synthons. The use of a mild base and green solvents provide access to these compounds, starting from widely available boronic acids and various [Au(NHC)Cl] complexes, with reactions taking place under air, at room temperature and leading to high yields with unprecedented ease. One compound, (N,N′-bis[2,6-(di-isopropyl)phenyl]imidazol-2-ylidene)(4-methoxyphenyl)gold, ([Au(IPr)(4-MeOC₆H₄)]), was synthesized on a multigram scale and used to gauge the reactivity of this class of compounds towards C−H/N−H bonds and with various acids, revealing simple pathways to gold–based species that possess attractive properties as materials, reagents and/or catalysts.     

Signature-dependent ml and e2 transition probabilities in 155ho and 157ho

¹⁵⁵Ho and ¹⁵⁷Ho have been populated in the reactions ¹⁴¹Pr(¹⁸O,4n) and ¹⁴⁶Nd(¹⁵N, 4n) at 85 and 74 MeV, respectively. In both nuclei bands built on the $\text{7}\text{2}$?[523] configuration were established to spin values considerably above the first backbend. A signature dependence in the excitation energies as well as in the ratio of M1 to E2 transition rates is observed below, but not above, the backbend in both nuclei. In ¹⁵⁷Ho lifetimes were measured with the recoil-distance method. The ΔI = 2; E2 transition probabilities obtained show very little variation with either signature or spin and no irregularity at the backbend. The signature dependence and strong rise in the ratio B(M1)/B(E2) observed at the backbend in ¹⁵⁷Ho therefore must be caused by the B(M1) values. A signature dependence in the B(E2, I → I ?1)/B(E2, I → I ?2) ratios also found in ¹⁵⁷Ho below the backbend is mainly the result of signature dependence in the ΔI = 1 ; E2 transition rates. Qualitatively, most of the features observed can be explained by nonaxial deformations, which change from large negative to slightly positive values of γ at the backbend.     

Yrast band spectroscopy of132Sm and130Nd

The states in the yrast band of¹³² Sm have been identified for the first time up to J^π=16⁺. The yrast band of¹³⁰Nd has also been extended from J^π=16⁺ to 24⁺. The energy of the first 2⁺ state in¹³²Sm indicates that the quadrupole deformation ε₂ ～ 0.3 and is still increasing as the neutron number N decreases across the samarium isotopes. The results for¹³⁰Nd allow the (h_2/11)² proton crossing frequency to be determined as ω=0.325 ± 0.005 MeV/?. This result is compared with cranked shell model predictions.     

Evidence for an i13/2 neutron band in133Sm

A rotational band of nine γ-rays has been observed in¹³³Sm. The moment of inertia of the band indicates that it has a higher deformation than expected for states in nuclei in this region. The properties are such that it can be interpreted as being due to the odd neutron occupying the ν i2/13 nn intruder orbital. This is the first evidence for the occupation of this orbital in nuclei with neutron number N<73.     

Classical and quantum mechanical systems of Toda-lattice type

Communications in Mathematical Physics - In a previous paper it was shown that certain Schrödinger operatorsH=Δ − V onR ℓ such as the Hamiltonians for the quantized...