[2,6‐Bis(3,5‐di­methyl­pyrazol‐1‐yl­methyl‐κN2)­pyridine‐κN]bis­(thiocyanato‐N)copper(II)

The title compound, [Cu(NCS)₂(C₁₇H₂₁N₅)], displays a distorted square‐pyramidal coordination geometry, where the basal plane is defined by the tridentate ligand and by one of the thio­cyanate ions. The apical position is occupied by the other thio­cyanate ion.     

Molecular orbital calculation of structures and spin densities of AsCl3− and AsF3−

Molecular orbital calculations were performed using the LCAO MO iterative extended Hückel procedure on the 27 valence electron species AsF₃^? and AsC₃^?. It was found that theory predicts the shape and unpaired spin-density distribution fairly well. The method is potentially useful especially since optimally parametrised CNDO and INDO techniques have not been developed to include the III or IV row elements of the periodic Table.     

EPR study of Mn2+ doped nanocrystalline PbF2

Nanocrystalline samples of PbF2 doped with 0.05, 0.1, 0.4 and 1 mol% Mn2+, used as paramagnetic probe, were prepared by inert gas condensation technique. All the samples were vacuum annealed at different temperatures to get different grain sizes. The X-ray diffraction studies showed the dominant content of -PbF2 phase with a fractional quantity of -PbF2. Thermal stability and sublattice melting were studied by TGA and DSC respectively. EPR measurements were made on all these samples at 77 and 300 K. The EPR spectra of all samples were found to contain well resolved sextet arising from the Mn2+ ions that occupied the cubic sites of Pb2+ ion of PbF2 lattice. The lower concentration of the Mn2+ ions (0.05 and 0.1 mol%) clearly monitored the Pb2+ environment in the PbF2 lattice. The 0.4 mol% showed the presence of only the cubic sites with a minor concentration of the orthorhombic sites. The spectra corresponding to 1 mol% Mn2+ clearly showed two different components. The isotropic nature of the 1 mol% as-prepared sample implied that there was no cluster formation and hence this EPR spectrum was taken as the single ion spectrum. The annealed samples contain two spectral components; one is from the isolated single ions and the other one from the Mn2+ clusters. The spectral component of Mn2+ clusters was obtained by subtracting the spectrum for the as-prepared sample for the spectra of annealed samples. The extracted cluster phase spectra and the pure spectrum from the as-prepared sample were then combined to simulate the entire set of experimental spectra. The simulated spectra were found to be in good agreement with the experimental data. The g values obtained were in the range very close to the free electron g factor as the electrons are in the S state (L=0).     

An efficient deprotection method for 5′-[O,O-bis(pivaloyloxymethyl)]-(E)-vinylphosphonate containing oligonucleotides

5′-(E)-Vinylphosphonate (VP) is an effective bioisostere of the natural 5′-monophosphate in small interfering RNAs (siRNAs). Solid-phase synthesis of VP-siRNAs requires the use of appropriately protected VP-phosphoramidites in combination with optimal oligonucleotide deprotection conditions. Addition of 3% (v) neat diethylamine to the standard aqueous ammonia deprotection conditions allows clean and rapid one-step deprotection of 5′-[O,O-bis(pivaloyloxymethyl)] (POM)-protected VP oligonucleotides, minimizing side reactions and impurities, which broadly enhances the scope of VP oligonucleotide synthesis.     

Crystal and molecular structure ofN-methylphenazinium bis(benzene-1,2-dithiolato)nickelate(III). Structure of (C13H11N2)[Ni(S2C6H4)2]

The crystal and molecular structure of the title compound, (C₁₃H₁₁N₂)[Ni(S₂C₆H₄)₂], is reported. Crystals are triclinic, space groupP¯1(No.2) withZ=2 in a unit cell of dimensionsa=9.363(1),b=10.148(1),c=13.623(1) Å,=85.64(1),=107.33(1), and =113.10(1)°. The structure was solved by the heavy-atom method and refined by the method of full-matrix least squares toR=0.036 for 2874 unique reflections. The metal atom of the anion has an approximate square-planar configuration. The metal atoms occupy the origins and A-face centers of the lattice. The anions with the metal atoms in the origins stack along thec-axis, the interplanar separation being thec-axis lattice repeat of 13.623(1) Å. The anions with the metal atoms in theA-face centers and the cations form a mixed stack along the short diagonal of theab-plane. The short interplanar distances (C–A=A–C=3.43 Å and C-C=3.91 Å) in the mixed stack (CAC-CAC) show the possibility of unusual electrical behavior. There is no evidence of direct or indirect metal-metal interaction.This work was supported by the Department of Science and Technology, Government of India, New Delhi, for which we are grateful. One of the authors (PK) also expresses his thanks to the U.G.C., New Delhi and Pachaiyappas College, Madras, for the award of FIP Fellowship.     

Crystal and molecular structure of bromo-bis(bis-diphenylphosphino-ethylene)-nickel(II)-tetraphenylborate

The Ni(II) complex of the ligandcis-1,2[bis(diphenylphosphino)ethylene] (VPP), [Ni(VPP)₂Br]BPh₄, crystallizes in the orthorhombic space groupP2₁2₁,2, witha=25.971(6),b=24.508 (6),c=19.642(5) Å,Z=8. The structure was determined by the procedure DIRDIF from Cu K automatic diffractometer X-ray data and refined by block-diagonal least-squares toR=11% for 5572 reflections. A question on the space group assignment betweenP2₁2₁2 andP2₁2₁2₁ was resolved only after the complete structure had been determined. The detailed crystal and molecular structure is presented.     

Synthesis of CeO2-NPs by chemical and biological methods and their photocatalytic,antibacterial and in vitro antioxidant activity

Research on Chemical Intermediates - In the present study, biosynthesized CeO2-NPs using Solanum nigrum leaf extract were compared with chemically synthesized one. The synthesized CeO2-NPs were...     

Water soluble Ru (II)–p‐cymene complexes of chiral aroylthiourea ligands derived from unprotected D/L‐alanine as proficient catalysts for asymmetric transfer hydrogenation of ketones

The newfangled chiral aroylthiourea ligands (L1‐L6) were produced from unprotected D/L‐alanine and their water soluble Ru (II) organometallic catalysts ( 1 – 6 ) were designed from their reaction with [RuCl₂(η⁶‐p‐cymene)]₂. The analytical and spectral methods were used to confirm the structure of the ligands and complexes. The solid state structure of L1, 5 and 6 was confirmed by single crystal XRD. The organometallic compounds ( 1 – 6 ) catalyzed the asymmetric transfer hydrogenation of aromatic, heteroaromatic and bulky ketones to yield respective enantiopure secondary alcohols with admirable conversions (up to 99%) and attractive enantiomeric excesses (ee up to 98%), in presence of formic acid and triethylamine in water medium under non‐inert atmospheric conditions.     

Bulk synthesis of polymer-inorganic colloidal clusters

We describe a procedure to synthesize colloidal clusters with polyhedral morphologies in high yield (liter quantities at up to 70% purity) using a combination of emulsion polymerization and inorganic surface chemistry. We show that the synthesis initially used for silica-polystyrene hybrid clusters can be generalized to create clusters from other inorganic and polymer particles. We also show that high yields of particular morphologies can be obtained by precise control of the inorganic seed particle size, a finding that can be explained using a hard-sphere packing model. These clusters can be further chemically modified for a variety of applications. Introducing a cross-linker leads to colloidal clusters that can be index matched in an appropriate solvent, allowing them to be used for particle tracking or optical studies of colloidal self-assembly. Also, depositing a thin silica layer on these colloids allows the surface properties to be controlled using silane chemistry.