A versatile synthesis of a new bisiminophosphorane

The iminophosphorane CH₂CH₂[P{NP(O)(OPh)₂}Ph₂]₂ is synthesized in high yields (80–97%) via a very convenient procedure using diphenylphosphoryl azide (DPPA) and 1,2-bis(diphenylphosphino)ethane.     

The bis(η5‐cyclo­penta­dienyl)­methyl­zirconium(IV) methyl­tris­(penta­fluoro­phenyl)­borate ion pair

The title complex, [Zr(CH₃)(C₅H₅)₂][CH₃B(C₆F₅)₃], crystallizes as an ion pair linked through an unsymmetrical methyl bridge. The bridging Zr—Me distance [2.556 (2) Å] is significantly longer than the terminal Zr—Me distance [2.251 (3) Å], while the Zr—C—B angle approaches linearity [169.1 (2)°].     

[Ferrocene‐1,1′‐diyl­bis­(diiso­propyl­phosphine‐P)]bis(phenylthio)palladium(II)

The Pd atom in the title compound, [Pd(C₆H₅S)₂(C₂₂H₃₆FeP₂)], possesses a distorted square‐planar geometry. The phenyl rings attached to the S atoms are located on opposite sides of the plane defined by the Pd and two S atoms. The Pd—S bonds are statistically significantly different, with values of 2.3703 (7) and 2.3887 (7) Å.     

Selective Patterned Growth of Single‐Crystal Ag–TCNQ Nanowires for Devices by Vapor–Solid Chemical Reaction

We report the deterministic growth of individual single‐crystal organic semiconductor nanowires of silver–tetracyanoquinodimethane (Ag–TCNQ) with high yield (>90%) by a vapor–solid chemical reaction process. Ag–metal films or patterned dots deposited onto substrates serve as chemical reaction centers and are completely consumed during the growth of the individual or multiple nanowires. Selective‐area electron diffraction (SAED) revealed that the Ag–TCNQ nanowires grow preferentially along the strong π–π stacking direction of Ag–TCNQ molecules. The vapor–solid chemical reaction process described here permits the growth of organic nanowires at lower temperatures than chemical vapor deposition (CVD) of inorganic nanowires. The single‐crystal Ag–TCNQ nanowires are shown to act as memory switches with high on/off ratios, making them potentially useful in optical storage, ultrahigh‐density nanoscale memory, and logic devices.     

NMSSM and seesaw physics at LHC

We consider extensions of the next-to-minimal supersymmetric model (NMSSM) in which the observed neutrino masses are described in terms of effective dimension six (or seven) rather than dimension five operators. All such operators respect the discrete symmetries of the model. The new particles associated with the double (or triple) seesaw mechanism can have sizable couplings to the known leptons, even with a TeV seesaw scale. In the latter case some of these new short-lived particles could be produced and detected at the LHC.     

Synthesis of tervalent phosphorus esters in biphasic system using potassium phosphate as unique solid base

The synthesis of tervalent phosphorus esters continues to be a significant area of interest, much of it again directed toward the synthesis of phosphite ligands for metal‐catalyzed reactions. Typically, they were obtained through esterification of the corresponding phosphorus chlorides with the appropriate alcohols in the presence of an amine. In this paper, we present a new method for the synthesis of tervalent phosphorus esters, not yet mentioned in the literature, when potassium phosphate, as a unique base, is used in liquid–solid system. Symmetrical and unsymmetrical phosphites were obtained with good yields (65%–80%) using this method. The compounds were characterized by ³¹P NMR spectroscopy. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:360–364, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20438     

Synthesis of Nitro‐Octaaza Derivatives of Reduced Anthracene

Nitro compounds of octaaza derivatives of reduced anthracene were synthesized for the first time by reaction of 2,3,4a,6,7,8a,9,10‐octaaza‐4,8‐dioxo‐3,4,4a,7,8,8a,9,9a,10,10a‐decahydroanthracene with nitric acid, mixed nitric acid/sulfuric acid, and nitric acid/acetic anhydride at between –20 and –30 °C. In addition, 1,2,4,5‐tetrazine azido derivatives were obtained by hydrolytic decomposition of the starting compound by nitrous acid. All the resultant compounds exhibit high thermal stability.     

Dissociation Energy Computations for Saline Bonds Implied in Interactions Mediated by Peptidoglicans

Summary: Dissociation energy and hydration energy calculations, in water solution, are presented for saline bonds mediated by Ca²⁺ and Mg²⁺ ions with Brőnstedt type bases ( COO ,  OSO₃ ,  OH). A computationally intensive method, Polarisable Continuum Model (PCM) using 6-31G^* basis set, was applied. Hydration energies were computed by various methods, as well as dissociation energies of some L₂M complexes. L₂Ca complexes result as more stable against dissociation than L₂Mg complexes. Hydration energy calculation results, for some of the methods, here used, seem rather reliable as compared to experimental results.     

Reduction of imines by hydroxycyclopentadienyl ruthenium hydride: intramolecular trapping evidence for hydride and proton transfer outside the coordination sphere of the metal

Reduction of imines by [2,5-Ph2-3,4-Tol2(eta(5)-C4COH)]Ru(CO)2H (2) produces kinetically stable ruthenium amine complexes. Reduction of an imine by 2 in the presence of an external amine trap gives only the complex of the newly generated amine. Reaction of 2 with H2N-p-C6H4N=CHPh (11), which contains an intramolecular amine trap, gave a 1:1 mixture of [2,5-Ph2-3,4-Tol2(eta(4)-C4CO)](CO)2RuNH(CH2Ph)(C6H4-p-NH2) (8), formed by coordination of the newly generated amine to the ruthenium center, and [2,5-Ph2-3,4-Tol2(eta(4)-C4CO)](CO)2RuNH2C6H4-p-NHCH2Ph (9), formed by coordination of the amine already present in the substrate. These results require transfer of hydrogen to the imine outside the coordination sphere of the metal to give a coordinatively unsaturated intermediate that can be trapped inside the initial solvent cage. Amine diffusion from the solvent cage must be much slower than coordination to the metal center. Mechanisms requiring prior coordination of the substrate to ruthenium would have led only to 8 and can be eliminated.     

Dinitrogen partial reduction by formally zero- and divalent vanadium complexes supported by the bis-iminopyridine system

Reduction of the two trivalent 2,6-{[2,6-(i-Pr)2C6H5]N=C(CH3)}2(C5H3N)VCl3 and {[2,6-{[2,6-(i-Pr)2C6H3]N-C=(CH2)}2(C5H3N)]VCl(THF) complexes with excess NaH afforded two corresponding end-on dinitrogen-bridged complexes [2,6-{[2,6-(i-Pr)2C6H5]N=C(CH3)}2(C5H3N)V]2(m-N2).(hexane) (1) and [{[2,6-{[2,6-(i-Pr)2C6H3]N-C=(CH2)}2(C5H3N)]V]2(m-N2).(hexane) (3). Despite their very close structural similarity, the two species have completely different natures. The first is paramagnetic and may be regarded as generated by the two-electron attack of two formally zerovalent vanadium moieties on the same N2 unit. In the nearly diamagnetic 3 instead, the N2 unit has been reduced by two vanadium atoms, formally divalent. Structural analysis and DFT calculations have indicated that partial reduction of the bridging nitrogen occurred for both complexes while, in the case of 1, substantial metal-to-ligand electron transfer also occurs.