151Eu-Mössbauer investigation in some new ternary Eu2M3Si5 systems (M=Ni,Pd, Cu,Rh)

The series Eu₂M₃Si₅ (M=Ni, Cu, Pd, Rh) have been synthesised for the first time. The Ni, Cu, Pd systems form in U₂Co₃Si₅ type structure.¹⁵¹Eu Mössbauer spectroscopy shows that Eu is in valence fluctuating (VF) state in Ni system, while in Cu and Pd systems it is in stable divalent state. These observations are further confirmed by magnetic susceptibility studies. The material Eu₂Rh₃Si₅ shows two lines in the Mössbauer resonance, one of which shows VF behaviour.     

Threshold anomaly in non-central forces

The behaviour of the threshold anomaly for non-central potentials, which account for collective excitations in heavy-ion collisions, is investigated. It is shown that the non-central potentials should exhibit an energy dependence at energies in the vicinity of the Coulomb barrier. This energy dependence is, however, different from that of the elastic optical potential, occurring at lower energies. It if further shown that there are corrections to the traditional collective model such that, if the transition potential is expressed as the derivative of the optical potential, the corresponding deformation length will be complex and energy-dependent. Simple model calculations are presented.     

Enolate alkylations with diethylbutadiene phosphonat-I

Enolates of various cyclic ketones undergo Michael addition to 1-diethyl-phosphinyl-1,3-butadiene to yield ketophosphonates.     

Stannoxanes and phosphonates: New approaches in organometallic and transition metal assemblies

Phosphonate ligands, [RPO₃]^2-, are extremely versatile in the assembly of multi-tin and multi-copper architectures. We have used organostannoxane cores for supporting multi-ferrocene and multi-porphyrin peripheries. The copper-metalated multi-porphyrin compound is an excellent reagent for facile cleavage of DNA, even in the absence of a co-oxidant. Reaction oft-BuPO₃H₂ with Cu(C10₄)₂. 6H₂O in the presence of 2-pyridylpyrazole (2-Pypz) leads to the synthesis of a decanuclear copper (II) assembly.     

Structural,magnetic and151Eu Mössbauer studies on EuTCu4 (T-Al,Pd and Ag) compounds

New ternary compounds having the formula EuTCu₄ where T=Al, Pd and Ag have been synthesized. All these compounds are found to crystallize in the hexagonal CaCu₅ type structure. Magnetization measurements reveal that these compounds are magnetically ordered with magnetic moments close to 7 μ_B. The Curie temperatures obtained from low field ac susceptibility measurements are 26K, 25K and 50K for T-Al, Pd and Ag respectively.¹⁵¹Eu Mössbauer studies at room temperature show a large negative isomer shift relative to SmF₃. A hyperfine split pattern is observed at 4.2K in all these compounds, indicating that Eu ion is present in a divalent state and is magnetically ordered.     

151Eu Mössbauer studies in the high Tc superconducting oxide materials

¹⁵¹Eu Mössbauer studies have been made across the respective superconductive transition temperatures in two compounds, La_1.7Eu_0.1Sr_0.2CuO_4?y and EuBa₂Cu₃O₇, having zero resistance state at 25K and 85K respectively. The¹⁵¹Eu isomer shift data establish that Eu ions are in trivalent state at all temperatures. The Mössbauer f-factor does not show any significant anomaly across the T_C.     

A novel transformation of 2-dichloracetamido-1-methyl-5-nitroimidazole to 5-dichloroacetylimino-tetrahydroimidazo (4,5-c) pyrazoles.

2-Dichloracetamido-1-methyl-5-nitroimidazole undergoes novel cycloaddition with diazomethane to form 5-dichloracetylimino-tetrahydroimidazopyrazoles via 2-dichloracetylimino-1,3-dimethyl-5-nitroimidazoline.     

Levels and transition probabilities in 124In as observed in the decay of 124Cd

The levels of ¹²⁴In, which are populated in the decay of ¹²⁴Cd, have been investigated at the OSIRIS on-line facility by means of conversion electron and γ-ray spectroscopy. A γ-γ coincidence measurement combined with the deduced transition intensities permitted construction of a unique level scheme. The half-life of the 243 keV level of ¹²⁴In has been determined to be 50 ± 6 ns by the method of delayed coincidences.     

Reaction of Anthranilamide with Phosphorus Pentasulfide: Formation of 2-Mercapto-(1H)-1,3,2λ5-benzodiazaphosphorine-2,4-dithione

The reaction of anthranilamide with phosphorus pentasulfide in boiling pyridine leads to the benzodiazaphosphorine-pyridine salt 2 . The structure is established by elemental analysis, ¹H- ¹³C- ¹⁵N- ³¹P-NMR, and mass spectral data.