Synthesis of bis(trithio)phosphines by oxidative transfer of phosphorus(I)

The synthesis of novel trithiobisphosphines is achieved by oxidative addition of tetrathiocins to the phosphorus(I) reagent [PIdppe][Br] in good yields under ambient conditions. These trithiobisphosphines and the related intermediate diphosphine species are characterized by X-ray diffraction and multinuclear NMR and a mechanism is proposed for the formation of these molecules

Synthesis and Structural Characterization of New Polyether Complexes of Germanium(II) and Tin(II)

A series of germanium(II) and tin(II) bromide polyether complexes have been synthesized. Specifically, [GeBr([15]crown-5)][GeBr3], [GeBr([18]crown-6)][GeBr3], [GeBr(triglyme)][GeBr3], [GeBr(tetraglyme)][GeBr3], [SnBr([18]crown-6)][SnBr3], [Sn([15]crown-5)2][SnBr3]2, [SnBr(triglyme)][SnBr3] and [SnBr(tetraglyme)][SnBr3] have been fully characterized including by single crystal X-ray diffraction. The synthesis of [GeBr(dibenzo[24]crown-8)][GeBr3] and [GeCl(dibenzo[24]crown-8)][GeCl3] are also reported, along with the crystal structure of the latterâ s water adduct, which features a water molecule adjacent to the GeCl+ ion within the cavity of the crown ether.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

New dihexadecyldithiophosphate SAMs on gold provide insight into the unusual dependence of adsorbate chelation on substrate morphology in sams of dialkyldithiophosphinic acids

We report the formation and characterization of new self-assembled monolayers (SAMs) formed from dihexadecyldithiophosphate (C16) 2DDP and compare their properties with those of SAMs formed from the structurally similar adsorbate dihexadecyldithiophosphinic acid (C 16)2DTPA. The new (C16)2DDP SAMs were characterized using X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, contact angle measurements, and electrochemical impedance spectroscopy. The data indicate that (C16)2DDP forms SAMs on gold films formed by e-beam evaporation in which all adsorbates chelate to gold, in contrast to (C16)2DTPA SAMs, in which 40% of the adsorbates are monodentate. The alkyl chains of the (C 16)2DDP SAM are also less densely packed and ordered than those of the (C16)2DTPA SAM. To understand these differences, we present density functional theory calculations that show that there are only minimal differences between the geometric and electronic structures of the two adsorbates and that the energetic difference between monodentate and bidentate binding of a gold(I) ion are surprisingly small for both adsorbates. This study leads to the conclusion that differences in intermolecular interactions within the SAM are the driving force for the difference in chelation between the two adsorbates. © 2013 American Chemical Society

Reactions of hybrid organotellurium ligands 1-(4-methoxyphenyltelluro)-2- 3-(6-methyl-2-pyridyl) propoxy ethane (L-1) and 1-ethylthio-2- 2-thienyltelluro ethane (L-2) with mercury(II) bromide: formation of complexes and their decomposition

Two tellurium ligands 1-(4-methoxyphenyltelluro)-2-[3 -(6-methyl-2-pyridyl)propoxy]ethane (L-1) and 1-ethylthio-2-[2-thienyltelluro]ethane (L-2) have been synthesized by reacting nucleophiles [4-MeO-C6H4Te-] and [C4H3S-2-Te-] with 2-[3-(6-methyl-2-pyridyl)propoxy]ethylchlo ride and chloroethyl ethyl sulfide, respectively. Both the ligands react with HgBr2 resulting in complexes of stoichiometry [HgBr2 (.) L-1/L-2] (1/4), which show characteristic NMR (H-1 and C-13{H-1}). On crystallization of I from acetone-hexane (2:1) mixture, the cleavage of L-1 occurs resulting in 4-MeOC6H4HgBr (2) and [RTe+ -> HgBr2]Br- (3) (where R = -CH2CH2OCH2CH2CH2-(2-(6-CH3-C5H3N))). The 2 is characterized by X-ray diffraction on its single crystal. It is a linear molecule and is the first such system which is fully characterized structurally. The Hg-C and Hg-Br bond lengths are 2.085(6) and 2.4700(7) angstrom. The distance of four bromine atoms (3.4041(7)-3.546(7) angstrom) around Hg (cis to C) is greater than the sum of van der Waal's radii 3.30 angstrom. This mercury promoted cleavage is observed for an acyclic ligand of RArTe type for the first time and is unique, as there appears to be no strong intramolecular interaction to stabilize the cleavage products. The 4 on crystallization shows the cleavage of organotellurium ligand L-2 and formation of a unique complex [(EtS(CH2)(2)SEt)HgBr(mu-Br)Hg(Br)(mu-Br)(2)Hg(Br)(mu-Br)BrHg(EtS(CH2)(2 )SEt)] (.) 2HgBr(2) (5), which has been characterized by single crystal structure determination and H-1 and C-13 {H-1} NMR spectra. The elemental tellurium and [C4H3SCH2](2) are the other products of dissociation as identified by NMR (proton and carbon-13). The cleavage appears to be without any transmetalation and probably first of its kind. The centrosymmetric structure of 5 is unique as it has [HgBr3](-) unit, one Hg in distorted tetrahedral geometry and one in pseudo-trigonal bipyramidal one. The molecule of 5 may also be described as having [(EtSCH2CH2SEt)HgBr](+) [HgBr3](-) units, which dimerize and co-crystallize with two HgBr, moieties. There are very weak Hg (...) Br interactions between co-crystallized HgBr, units and rest of the molecule. [Hg(3)-Br(1)/Hg(3)-Br(4) = 3.148(1)/3.216(1) angstrom]. The bridging Hg (...) Br distances, Hg(2)-Br(4)', Hg(2)'-Br(4) and Hg(1)-Br(2), are from 2.914(1) to 3.008(1) angstrom

Organoselenium(II) and selenium(IV) compounds containing 2-(Me2NCH2)C6H4 moieties: solution behavior and solid state structure

The cleavage of the Se-Se bond in [2-(Me2NCH2)C6H4]2Se2 (1) was achieved by treatment with SO2Cl2 (1:1 molar ratio) or elemental halogens to yield [2-(Me2NCH-)C6H4]SeX [X = Cl (2), Br (3), I (4)]. Oxidation of 1 with SO2Cl2 (1:3 molar ratio) gave [2-(Me2NCH2)C6H4]SeCl3 (5). [2-(Me2NCH2)C6H4]SeS(S)CNR2 [R = Me (6), Et (7)] were prepared by reacting [2-(Me2NCH2)C6H4]SeBr with Na[S2CNR2] . nH2O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K[(SPMe2)(SPPh2)N] resulted in isolation of [2-(Me2NCH2)C6H4]Se-S-PMe2=N-PPh2=S (8). The compounds were characterized by solution NMR spectroscopy (1H, 13C, 31P, 77Se, 2D experiments). The solid-state molecular structures of 2, 4-8 were established by single crystal X-ray diffraction. All compounds are monomeric, with the N atom of the pendant CH2NMe2 arm involved in a three-center-four-electron N •••Se-X (X = halogen, S) bond. This results in a T-shaped coordination geometry for the Se(II) atom in 2, 4, 6-8. In 5, the Se(IV) atom achieves a square pyramidal coordination in the mononuclear unit. Loosely connected dimers are formed through intermolecular Se•••Cl interactions (3.40 angstrom); the overall coordination geometry being distorted octahedral. In all compounds hydrogen bonds involving halide or sulfur atoms generate supramolecular associations in crystals

A 115In solid-state NMR study of low oxidation-state indium complexes

115In solid-state NMR (SSNMR) spectroscopy is applied to characterise a variety of low oxidation-state indium(I) compounds. 115In static wideline SSNMR spectra of several In(I) complexes were acquired with moderate and ultra-high field NMR spectrometers (9.4 and 21.1 T, respectively). 115In MAS NMR spectra were obtained with moderate and ultra-fast (>60 kHz) spinning speeds at 21.1 T. In certain cases, variable-temperature (VT) 115In SSNMR experiments were performed to study dynamic behaviour and phase transitions. The indium electric field gradient (EFG) and chemical shift (CS) tensor parameters were determined from the experimental spectra. With the aid of first principles calculations, the tensor parameters and orientations are correlated to the structure and symmetry of the local indium environments. In addition, calculations aid in proposing structural models for samples where single crystal X-ray structures could not be obtained. The rapidity with which high quality 115In SSNMR spectra can be acquired at 21.1 T and the sensitivity of the 115In NMR parameters to the indium environment suggest that 115In SSNMR is a powerful probe of the local chemical environments of indium sites. This work demonstrates that 115In NMR can be applied to a wide range of important materials for the purpose of increasing our understanding of structures and dynamics at the molecular/atomic level, especially for the characterisation of disordered, microcrystalline and/or multi-valence solids for which crystal structures are unavailable

Evolution of genes and genomes on the Drosophila phylogeny

Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species