Selective Hydrogenation of Organic Azides to Aminies by Interlameller Montmorill Onitediphenylphosphine Palladium(II) Catalyst

Organic azides are selectively and catalytically hydrogenated to amines by a hetergenized homogeneous catalyst for the first time.     

Quasi-one dimensional electrical conductivity and thermoelectric power studies on a discotic liquid crystal

We have studied the electrical conductivity of well aligned samples of hexahexylthiotriphenylene (HHTT) in the pure as well as doped states. The dopant used was a small concentration (0.62 mole %) of the electron acceptor trinitrofluorenone (TNF). In the columnar phases, doping causes the AC(1 kHz) conductivity along the columnar axis (σ _‖) to increase by a factor of 10⁷ or more relative to that in undoped samples; σ _‖ attains a value of 10⁻²S/m, which was the maximum measurable limit of our experimental set up. On the other hand, in the isotropic phase doping makes hardly any difference to the conductivity. The frequency dependence of the conductivity has been investigated. The DC conductivity of doped samples exhibits an enormous anisotropy, σ _‖/σ _⊥ ≥ 10¹⁰, which is 7 orders higher than that reported for any liquid crystalline system, and, to our knowledge, the largest observed in an organic conductor. We also report the first thermoelectric power studies on these ‘molecular wires’. The sign of the thermoelectric power is in conformity with the expected nature of the charge carriers, namely, holes.     

Erlenmeyer azlactone synthesis with aliphatic aldehydes under solvent-free microwave conditions

2-Phenyl-5(4H)-oxazolone (azlactone) reacts with aliphatic aldehydes upon adsorption on neutral alumina and irradiation with microwaves (<2 min). The corresponding condensation products are obtained in good yields (62-78%), indicating the satisfactory resolution of a long-standing problem plaguing the classical Erlenmeyer synthesis (poor results with aliphatic aldehydes). Plausible mechanistic reasons for the success of the procedure are discussed.     

Single crystal EPR and optical studies of paramagnetic ions doped zinc potassium phosphate hexahydrate—Part I: Cu(II)—a case of orthorhombic symmetry

Single crystal electron paramagnetic resonance (EPR) studies on Cu(II) doped zinc potassium phosphate hexahydrate (ZPPH) were carried out at room temperature. The angular variation spectra in the three orthogonal planes indicate that the paramagnetic impurity has entered the lattice substitutionally in place of Zn(II) and the spin Hamiltonian parameters calculated from these spectra are g(xx) = 2.188, g(yy) = 2.032, g(zz) = 2.373, Axx = 50 G, Ayy = 65.0 G and Azz = 80 G. The g and A tensors were coincident and these values matched fairly well with the values obtained from powder spectrum. The bonding parameters have also been calculated.     

NEW RING SYSTEMS OF ELEMENTS OF MAIN GROUPS IV AND V

Abstract

The synthesis of [PhSn(O)O₂CC₆H₁₁]₆ represents the first example of tin(IV) in a drum-shaped molecule. The formation of the dimeric composition, [(MeSn(O)O₂CC₆H₁₁)₂(MeSn(O₂CC₆H₁₁)₃]₂, appears to be an intermediate hydrolysis product on the way to the drum composition. The X-ray structure reveals an “unfolded” drum array. The distannoxane unit which is represented as the sides of the drum is found in additional new dimeric compositions, [(SCH₂CH₂O)₂SnCl]₂[H][Et₄N], [((CN)₂C₂S₂)₂SnOH]₂, and [BuSnCl₂(OH) · H₂O]₂. These all have six-coordinated tin atoms which contrasts to the dimeric aryl distannoxanes recently isolated, [Ph₂(Cl)SnOSnPh₂(X)]₂, X = OH, Cl, containing five-coordinated tin. Also isolated are the new ring containing, five-coordinated tin derivatives, [(SCH₂CH₂S)₂Sn]₂[SCH₂CH₂S][Et₃NH]₂ and [(SC(CN)C(CN)S)₂SnMe][Et₄N]. The former has two trigonal bipyramidal tin atoms while the latter composition has a square pyramidal geometry. Related ring systems of new five-coordinated derivatives of silicon, germanium, arsenic, and antimony that span the range between the two ideal five-coordinated geometries also have been structurally characterized.     

Chemoselective Reduction of Carbonyl Compounds with PMHS - ZnCl2

An inexpensive and safer reagent system comprising of PMHS and ZnCl₂ has been developed for the selective reduction of carbonyl compounds to corresponding alcohols.

     

Thin films of Ln1−xSrxCoO3 (Ln=La, Nd and Gd) and SrRuO3 by nebulized spray pyrolysis

Thin films of La_1−xSr_xCoO₃, Nd_0.5Sr_0.5CoO₃, Gd_0.5Sr_0.5CoO₃ and SrRuO₃ have been deposited on Si(100), LaAlO₃(100) and SrTiO₃(100) single crystal substrates by nebulized spray pyrolysis. The films deposited on Si are generally polycrystalline, but they are highly oriented on the oxide substrates. The cobaltate films are generally not metallic, but exhibit low resistivity specially when x=0.3 and 0.5, the latter also exhibiting ferromagnetic characteristics. Films of La_0.7Sr_0.3CoO₃ show negative magnetoresistance of 35% around 180 K. Films of SrRuO₃ are metallic on Si and LaAlO₃ substrates but show an insulator–metal transition on SrTiO₃ around 130 K, around which temperature negative magnetoresistance is observed.