trans‐[1,3‐Bis(2,4,6‐trimethylphenyl)imidazolidin‐2‐ylidene]dichlorido(triphenylphosphine‐κP)palladium(II)

The title complex, [PdCl₂(C₂₁H₂₆N₂)(C₁₈H₁₅P)], shows slightly distorted square‐planar coordination around the Pd^II metal centre. The Pd—C bond distance between the N‐heterocyclic ligand and the metal atom is 2.028 (5) Å. The dihedral angle between the two trimethylphenyl ring planes is 36.9 (2)°.     

Highly Regioselective Sequential 1,1‐Dihydrosilylation of Terminal Aliphatic Alkynes with Primary Silanes

A regioselective double 1,1‐hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem‐Bis(dihydrosilyl)alkanes containing four silicon‐hydrogen bonds are efficiently constructed in an atom‐economical manner. Tolerated substrates include simplest alkyne‐ethyne, a complicated drug derivative and various functionalized terminal aliphatic alkynes. Asymmetric approach using two catalysts is achieved with excellent enantioselectivities to access corresponding chiral products. The transformations of Si—H bonds into Si—C, Si—O, and Si—F bonds and the synthesis of enantioriched α‐hydroxysilane show synthetic utility.     

First‐ and second‐ sphere coordination of the uranyl ion by bis­[2‐(2‐hydroxy­phenoxy)­ethoxy]­ethane

Uranyl nitrate hexahydrate reacts with bis­[2‐(2‐hydroxy­phenoxy)­ethoxy]­ethane (C₁₈H₂₂O₆), denoted LH₂ hereafter, in the presence of triethylamine to give ­triethylammonium aqua[2,2′‐(3,6‐dioxaoctane‐1,8‐diyldioxy)diphenolato‐κ²O,O′](nitrato‐κ²O,O′)dioxouranium(VI), (Et₃NH)[UO₂(H₂O)L(NO₃)], which possesses a symmetry plane. The uranyl ion is coordinated to the two phenoxide O atoms, a nitrate ion and a water mol­ecule (first sphere); the water mol­ecule is itself held in the crown ether chain by hydrogen‐bonding interactions, thus ensuring second‐sphere coordination by the ligand L.     

Synthesis and Biological Activity of Some New Pyrazolo[3,4‐b]Pyrazines

New derivatives of pyrazolo[3,4‐b]pyrazine and related heterocycles were prepared starting from 6‐amino‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyrazine‐5‐carbonitrile ( 2 ) and using the key intermediates 4 , 5 , 6 , 14 , 15 and 16 . Some of the prepared compounds were evaluated for their antifungal and antibacterial activities.     

Application of Liquid Crystalline NMR Solvents to a Mixture of Ketones

A series of dilute liquid crystalline solvents are used to study the effect of slight anisotropy caused by partial alignment on chemical shift and residual dipolar coupling (RDC) in small molecules. The residual dipolar couplings between protons in solutes are found to be almost independent of the local environment. It is also found that the chemical shift does not change over the concentration range observed. A linear relationship between residual dipolar coupling and liquid crystal concentration is observed at relatively low concentrations, but is severely violated at high concentrations.     

A Structural Study of the Solid Solution Eu2(Mo1‐xWx)3O12

A structural study by means of X‐ray and electron diffraction of intermediate oxides between Eu₂Mo₃O₁₂ and Eu₂W₃O₁₂ shows the existence of a new Eu₂(Mo_1?xW_x)₃O₁₂ solid solution with the scheelite structural type. The essential feature of the x = 1/3 and x = 2/3 compounds is the presence of isolated oxygen tetrahedra, in which, according to X‐ray and electron diffraction data, W and Mo are randomly distributed. Eu atoms occupy distorted square antiprisms sites.