Dalton Transactions Blog

In this HOT article, a very careful synthetic and catalytic study of the use of di- and trisulfonated phosphines with o, m and o, m, m substitution patterns is described. Pd complexes of these were tested for  copolymerizations with polar monomers. This led to a novel anionic phosphine sulphonate Pd(II)-based pre-catalyst salt for polymerisation reactions.  Although, polymerisation in the presence of methyl acrylate, acrylonitrile and vinyl acetate led to reduced incorporation values compared to the available literature reports in combination with problems that are attributed to aggregation of the catalyst in most cases, the facile synthesis of chelating highly polar ligands which show high water solubility could be of significant interest for homogeneous catalysis by application in other systems.

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Synthesis of non-symmetrically sulphonated phosphine sulphonate based Pd(II) catalyst salts for olefin polymerisation reactions
Timo M. J. Anselment, Carly E. Anderson, Bernhard Rieger, M. Bele Boeddinghaus and Thomas F. Fässler
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10372E

In this HOT article, the authors have extended their work in understanding enantioselective catalysis by coordination compounds. The role of steric hindrance in controlling the binding mode of propylene oxide to a novel vanadyl salen-type complex N,N‘-bis(5-tert-butylsalicylidene)-1,2-cyclohexanediamino-vanadium(IV) oxide, [VO(3)], has been investigated using CW/pulse EPR, ENDOR and HYSCORE spectroscopy and compared to that of the parent complex N,N‘-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamino-vanadium(IV) oxide, [VO(1)]. Removal of the ‘inner tert-butyl groups from the salicylidene rings reduces the steric hindrance between the ligand and epoxide substrate. As a result the selectivity for binding single enantiomers of propylene oxide in these complexes is reversed in [VO(3)] relative to [VO(1)].

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Structure and pulsed EPR characterization of N,N‘-bis(5-tert-butylsalicylidene)-1,2-cyclohexanediamino-vanadium(IV) oxide and its adducts with propylene oxide
E. Carter, I. A. Fallis, B. M. Kariuki, I. R. Morgan, D. M. Murphy, T. Tatchell, S. Van Doorslaer and E. Vinck
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10378D

In this HOT article, the molecular structures of 1,2-closo-P₂B₁₀H₁₀ (1) and 1,2-closo-As₂B₁₀H₁₀ (2) have been determined by gas electron diffraction and the results obtained compared with those from computation at the MP2/6-31G** level of theory. The first examples of metalladiphosphaboranes and a considerable extension of the range of known metalladiarsaboranes, these compounds being prepared from deboronated derivatives of 1 and 2, respectively, are also reported.

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New chemistry of 1,2-closo-P₂B₁₀H₁₀ and 1,2-closo-As₂B₁₀H₁₀; in silico and gas electron diffraction structures, and new metalladiphospha- and metalladiarsaboranes
R. McLellan, N. M. Boag, K. Dodds, D. Ellis, S. A. Macgregor, D. McKay, S. L. Masters, R. Noble-Eddy, N. P. Platt, D. W. H. Rankin, H. E. Robertson, G. M. Rosair and A. J. Welch
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10540J

Rechargeable lithium-ion batteries (LIBs) have successfully dominated the commercial power supply market for advanced portable electronics.  In this regard, metallic Sn has attracted a great deal of interest as an anode material because of its high theoretical capacity offering a significant advantage over the currently used graphite but until now has not been utilized due to the huge volumetric changes during Li-insertion/extraction cycling, which leads to rapid pulverization and poor cyclability of the materials. 

This HOT article reports an interesting study on Sn/PPy composite as negative electrode using carboxymethyl cellulose (CMC) binder for Li-ion batteries.   The electrochemical results show that both the capacity retention and the rate capability are in the same order of nano-Sn/PPy-CMC > nano-Sn/PPy-PVDF > nano-Sn-CMC > nano-Sn-PVDF. Scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS) results show that CMC can prevent the formation of cracks in electrodes caused by the big volume changes during the charge–discharge process, and the PPy in the composite can provide a conducting matrix and alleviate the agglomeration of Sn nanoparticles. The present results indicate that the nano-Sn/PPy composite could be suitable for the next generation of anode materials.

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Tin/polypyrrole composite anode using sodium carboxymethyl cellulose binder for lithium-ion batteries
Shu-Lei Chou, Xuan-Wen Gao, Jia-Zhao Wang, David Wexler, Zhao-Xiang Wang, Li-Quan Chen and Hua-Kun Liu
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10396B

In this HOT article, a  low-dimensional compound [C₆-Apy][Ni(mnt)₂] (where mnt^2- = maleonitriledithiolate, C₆-Apy⁺ = 4-amino-1-hexylpyridinium) has been designed and synthesized, which has a layer arrangement of anions and cations and shows two steps of magnetic transitions. The low temperature magnetic transition has an uncommon hysteresis loop, while the crystal structure investigations disclosed no structural transition with the magnetic transition. The high temperature magnetic transition exhibits two remarkable features: (1) it synchronously occurs with a crystalline-to-mesophase transition in the first heating process and (2) the structural changes that accompany the solid-mesophase transition are irreversible. It is hoped that the results will shed new light on the design and preparation of a new low-dimensional molecular system combining magnetic transition and liquid crystal properties.

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A low-dimensional molecular spin system with two steps of magnetic transitions and liquid crystal property
Hai-Bao Duan, Xiao-Ming Ren, Lin-Jiang Shen, Wan-Qin Jin, Qing-Jin Meng, Zheng-Fang Tian and Shi-Ming Zhou
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C0DT01704C