NOPR Collection:

Thermodynamics of ternary mixtures: Excess isentropic compressibilities

Sat, 01 Feb 2003 00:00:00 GMT

Title: Thermodynamics of ternary mixtures: Excess isentropic compressibilities Authors: Sharma, V K; Kalra, K C; Romi; Katoch, Ashma Abstract: Ultrasonic velocity data for nitrobenzene(i) + benzene(j) + toluene, or + o-xylene, or + p-xylene (k) ternary mixtures have been determined as a function of composition at 298.15K. The observed data have been utilized to evaluate excess isentroic compressibilities, K, K values have also been computed using Flory theory. It has been observed that K values evaluated from Flory theory make qualitative agreement with the values evaluated from experimental data. Page(s): 292-294

A novel magnetic exchange mechanism in bridged copper (II) coordinations of naturally occurring spin carriers viz. ortho-functionalized p-naphthoquinones

Sat, 01 Feb 2003 00:00:00 GMT

Title: A novel magnetic exchange mechanism in bridged copper (II) coordinations of naturally occurring spin carriers viz. ortho-functionalized p-naphthoquinones Authors: Rane, Sandhya; Gawali, Sunita; Padhye, Subhash; Date, Sadgopal; Bakare, Pramod Abstract: Magnetic exchange and charge transfer mechanisms in dimeric (1) [Cu(Lw)₂H₂O] and monomeric (2), [Cu(phth)₂] complexes of lawsone (2-hydroxy-1,4-naphthoquinone) and phthiocol (3-methyl-2-hydroxy 1,4-naphthoquinone) are described. Magnetic susceptibility measurements of (1) are fitted to Heisenberg's isotropic spin pair (S' = 1,1) model and tetranuclear (S' = ½, ½,½, ½) spins in a two dimensional model. Both models result in intradimer antiferromagnetic coupling (J = -44.4 cm^-1) between [Cu(NSQ)]₂ units and ferromagnetic coupling (zJ₁ = 28.5 cm^-1) between one Cu(II)NSQ coordinated unit (where NSQ = naphtho-semiquinone).
Latter interaction leads to a triplet ground state and triplet-triplet intradimer interaction governs the ‘‘quintet state’’ at room temperature, as detected from X- and Q-band EPR studies. The zero- field split interaction (0.024 cm^-1) exhibits contributions from D_pd (-0.071 cm^-1) and combined D_d and D_anti (+0.095 cm^-1) interactions. The intradimer exchange is due to a stacked (S' = 1,1) spin pair with r = 3.04Å. The monomeric complex (2) is devoid of such interactions due to the bulky methyl group at C3 position of quinonoid ring.
Cyclic voltammograms of (1) and (2) show an anodic peak at +0.22 V, assigned to Cu(0) → Cu(II) charge transfer. Only one redox couple at E_1/2= -0.687 V due to NSQ CAT (catechol) charge transfer leads to radical coordination in (1). However, quarsireversible NQ NSQ redox couple at E_1/2 = -0.525 V together with an irreversible NSQ → CAT reduction peak in (2) at E_1/2= -0.75 V indicate fully the presence of oxidized (NQ) i.e. naphthoquinone ligation in (2). Page(s): 255-261

A rapid spectrophotometric method for the determination of trichloromethane sulphenyl chloride derivatives and commercial fungicides

Sat, 01 Feb 2003 00:00:00 GMT

Title: A rapid spectrophotometric method for the determination of trichloromethane sulphenyl chloride derivatives and commercial fungicides Authors: Sharma, D K; Sood, Sunita; Kumar, Ramesh; Verma, B C Abstract: A new, simple and rapid spectrophotometric method for the microdetermination of trichloromethane sulphenyl chloride derivatives (RSCCl₃) based on their reaction with thiophenol in acetonitrile in the presence of triethylamine is described. The yellow colour, which develops instantaneously on mixing the reagents in acetonitrile, is stable for atleast 6 h and is measured at 450 nm. Beer's law is applicable upto 200 μg ml^-1 of each derivative concentration. The method has been successfully adapted to the analysis of captan and folpet fungicides based on these derivatives in their commercial formulations for the purpose of quality control. Page(s): 331-332

One-dimensional chain crown ether complexes: Synthesis and crystal structure of [Na(18-crown-6)]₂[M(mnt)₂](M = Zn, Cd)

Sat, 01 Feb 2003 00:00:00 GMT

Title: One-dimensional chain crown ether complexes: Synthesis and crystal structure of [Na(18-crown-6)]₂[M(mnt)₂](M = Zn, Cd) Authors: Yu, Qingjiang; Dou, Jianmin; Li, Dacheng; Wang, Daqi; Zhong, Baoyun; Wei, Yong; Zheng, Peiju Abstract: The reactions of IR-crown-6 with Na₂[Zn(mnt)₂] and Na₂[Cd(mnt)₂] have been studied and the complexes [Na(18-crown-6)]₂[M(mnt)₂](M = Zn, Cd), are characterized by elemental analysis, IR spectrum and X-ray diffraction analysis. 1 and 2 belong to monoclinic, space group c2/c with cell dimensions, 1: a = 2.2418(6), b = 1.1359(3), c = 1.9887(6) nm, β= 120.391 (4)^o, V = 4.368(2), nm³, Z = 4, Dcalcd = 1.399 Mg/m³, F(000) = 1920, R₁ = 0.0302, wR₂ = 0.0560 and 2: a = 2.2547(6), b = 1.1412(3), c = 1.9938(6) nm, β=119.715(4)°, V = 4.455 nm³, Z = 4, Dcalcd = 1.442 Mg/m³, F(000)= 1992, R₁ = 0.0384, wR₂ = 0.0575. Two complexes display a one-dimensional chain of [Na(18C6)]⁺(complex cations and [M(mnt)₂]^2- (M = Zn, Cd) complex anion bridged by Na-O interactions between adjacent [Na(18C6)]⁺units respectively. Page(s): 327-330

NOPR Collection:

Thermodynamics of ternary mixtures: Excess isentropic compressibilities

A novel magnetic exchange mechanism in bridged copper (II) coordinations of naturally occurring spin carriers viz. ortho-functionalized p-naphthoquinones

A rapid spectrophotometric method for the determination of trichloromethane sulphenyl chloride derivatives and commercial fungicides

One-dimensional chain crown ether complexes: Synthesis and crystal structure of [Na(18-crown-6)]2[M(mnt)2](M = Zn, Cd)

One-dimensional chain crown ether complexes: Synthesis and crystal structure of [Na(18-crown-6)]₂[M(mnt)₂](M = Zn, Cd)