Sixty-Year Saga (1952–2013) of the Solid-State Structure of Triiron Dodecacarbonyl

This article presents the personal saga of one of the authors (LFD) in the determination of the solid-state structure of Fe₃(CO)₁₂. We also present the results of our recent determination of its solid-state structure at low temperature (100 K), in which we have used a modern area-detector diffractometer in order to examine more precisely its temperature-dependent structural variations reported by Braga et al. in 1994 from a point-detector diffractometer. These investigations provide a striking illustration of the remarkable advances over the last six decades in both computational hardware and software packages as well as the recent improvements in hardware data-collection instrumentation that have given rise to X-ray crystallography now being the most powerful (and in most cases the only unambiguous) physical method for elucidating the static structures of complex metal clusters. Other experimental measurements and resulting speculations concerning the dynamic/fluxional behavior of Fe₃(CO)₁₂ and closely related analogues in the solid state and in solution are briefly mentioned, as are recent theoretical analyses.     

Synthesis and unusual photochemistry of a highly reactive pyrimidinedione

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Solvent-free synthesis of tris(4-hydroxybutyl acrylate) phosphate in the presence of 1-methylimidazole

In this paper, we present the synthesis of tris(4-hydroxybutyl acrylate) phosphate using 1-methylimidazole as acid scavenger for hydrochloric acid by-product, when an ionic liquid is formed. The synthesis was performed in the absence of any organic solvent. The yield is 83% for ester. The phosphate was characterized by ¹H–³¹P NMR and FTIR. The obtained phosphate is appropriate monomer for UV curing in the presence of photoinitiator. The obtained polymer was characterized by thermal analysis and LOI. The results showed good thermal stability and flame retardancy of UV-cured polymer.     

Microwave-assisted synthesis and antitumor activity of the supramolecular complexes of betulin diacetate with arabinogalactan

In this work, a water-soluble supramolecular complex was synthesized in an aqueous suspension of betulin diacetate (BDA) and arabinogalactan (AG) upon microwave heating. Microwave heating allows reducing the time required for the complex formation, compared with conventional heating in a water bath. The specific effect of microwave irradiation on the initial reagents and preparation of a supramolecular complex was studied. In contrast to conventional heating, under microwave heating AG macromolecules may break into roughly equal fragments when the temperature increases up to 100 °C. A change in the surface morphology of BDA crystals under microwave heating of the suspension suggests that microwave irradiation facilitates the dissolution of BDA in water. It has been shown that the use of dimethylsulfoxide as a reaction medium for microwave heating led to a decrease in BDA content in the product due to the inclusion of DMSO into AG macromolecules. The BDA–AG complex was isolated from the microwave-heated aqueous solution, after water evaporation, as a thin amorphous film, which exhibited antitumor activity against Ehrlich ascites carcinoma cells and can be a promising material for pharmacological applications.     

Inverse seesaw in NMSSM and 126 GeV Higgs boson

We consider extensions of the next-to-minimal supersymmetric model (NMSSM) in which the observed neutrino masses are generated through a TeV scale inverse seesaw mechanism. The new particles associated with this mechanism can have sizable couplings to the Higgs field which can yield a large contribution to the mass of the lightest CP-even Higgs boson. With this new contribution, a 126 GeV Higgs is possible along with order of 200 GeV masses for the stop quarks for a broad range of tan β. The Higgs production and decay in the diphoton channel can be enhanced due to this new contribution. It is also possible to solve the little hierarchy problem in this model without invoking a maximal value for the NMSSM trilinear coupling and without severe restrictions on the value of tan β.     

Efficient synthesis of functionalized furans and benzofurans based on a ‘[3+2] cyclization/oxidation’ strategy

Functionalized furans and benzofurans were prepared by DDQ oxidation of 2-alkylidenetetrahydrofurans, which are readily available by one-pot cyclizations of 1,3-dicarbonyl dianions or 1,3-bis-silyl enol ethers.     

Bis­(iso­propyl­amino)­methyl­carbenium tetrakis­(penta­fluoro­phenyl)­gallate

The title compound, [MeC(NHⁱPr)₂][Ga(C₆F₅)₄] crystallizes as discrete ions forming interionic hydrogen bonds of the type N—H?F.     

Oligomerization of N‐Heterocyclic Silylene into Zwitterionic Silenes

N‐Heterocyclic carbenes (NHC's) are known to serve as efficient substrates for the stabilization of various transient species possessing low‐valent Group 14 elements and for the generation of double E=C bonds. Herein, we report that the thermal tri‐ and tetramerizations of pyridoannulated silylene 1 lead to the formation of remarkably stable silenes 2 and 3 featuring zwitterionic distribution of electron density. Co‐oligomerization of 1 and its germanium analogue gives a related tetrameric product 4 containing low‐valent germanium atom stabilized by binding with the partial carbene‐character C atom. Bonding situations in 2 – 4 are best described as silene or germene with the significant zwitterionic distribution of electron density. The singlet diradical electronic state of 2 is 10 kcal mol^?1 higher than the ground state configuration.