On the photometric determination of trivalent rhodium with eriochromecyanine RC

Summary Eriochromecyanine RC has been used as chromogenic reagent for the photometric determination of rhodium(III) on a micro scale. A coloured Rh(III)-ECRC chelate with _max 530 nm at pH 4.0 (25°C) is formed. A detailed study has been made concerning to characteristics, composition and stability of the chelate. Standard deviation was ±1.17%.

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Über die photometrische Bestimmung von dreiwertigem Rhodium mit Eriochromcyanin RC

Zusammenfassung Ergebnisse einer Untersuchung über die Zusammensetzung und Stabilität des Komplexes werden mitgeteilt. Das Absorptionsmaximum liegt bei 530 nm (pH 4,0; 25°C). Bestimmungen konnten mit einer Standardabweichung von ±1,17% durchgeführt werden.

     

Thermal analysis of lanthanide polyphosphates

Summary A study of thermal analysis of some lanthanide polyphosphates has been reported. The DTA curves of Ce, Pr and Sm polyphosphates were of similar nature. They exhibited a sharp exothermic peak indicating crystallization temperature (T _c) around 520 °C. However, no peak indicatingT _m was observed upto 800 °C. TG curves of Ce, La, Pr, Sm, Y polyphosphates indicated weight loss occurring in three stages. The integral procedural decomposition thermal analysis (ipdt) indicated that these materials had refractory nature.With 4 figures and 2 tables     

Spectrophotometric determination of indium using gallion

Summary The formation of violet coloured chelate of indium with Gallion has been studied. Indium forms only one chelate with Gallion at p_H 4.5 having _max 610 nm. The composition of the complex formed has been determined by various methods and is found to be 11 (MR). The values of stability constant have been calculated by three methods and the average value of logK obtained is 5.6 ± 0.1. A procedure for the spectrophotometric determination of indium has been suggested.

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Zusammenfassung Die Bildung eines violetten Chelates von Indium mit dem Reagens Gallion wurde studiert. In bildet damit ein einziges Chelat bei p_H=4,5 und _max=610 nm. Die Zusammensetzung des entstandenen Komplexes wurde nach verschiedenen Methoden ermittelt und gleich 11 (MetallReagens) gefunden. Die Stabilitätskonstante wurde nach drei Verfahren berechnet, wobei sich als Mittelwert logK=5,6±0,1 ergab. Eine Arbeitsvorschrift für die spektrophotometrische Bestimmung des In wird vorgeschlagen.

     

Novel terpenoids from the West Indian sea whip Pseudopterogorgia elisabethae (Bayer). Elisapterosins A and B: rearranged diterpenes possessing an unprecedented cagelike framework

Four diterpenes and a nor-diterpenoid, all of which possess unusual carbocyclic skeletons, were isolated from the hexane solubles of the West Indian gorgonian Pseudopterogorgia elisabethae. The structures and relative configurations of novel metabolites elisabethin D (2), elisabethin D acetate (3), 3-epi-elisabanolide (5), elisapterosin A (6), and elisapterosin B (7) were elucidated by interpretation of overall spectral data, which included 2D NMR correlation methods, IR, UV, and accurate mass measurements (HREI-MS and HRFAB-MS), chemical reactions, and X-ray diffraction analyses. The tetracyclic carbon skeleton of the elisapterosins is undescribed and constitutes a new class of C(20) rearranged diterpenes. Elisapterosin B displays strong in vitro anti-tuberculosis activity.     

Heats of solution and neutralization ofLewis acids and bases in acetic anhydride

Heats solution of someLewis acids and bases in acetic anhydride have been determined and the following order of their relative strengths is proposed: SbCl₅>SO₃>SnCl₄>TiCl₄>AsCl₃ and piperidine> n-butylamine>potassium acetate>sodium acetate -picoline>quinoline. Heats neutralization of theseLewis acids and bases in acetic anhydride suggest that the major enthalpy change in these neutralization reactions is due to the combination of a proton and the (CH₂COOCOCH₃)-ion, resulting in the formation of acetic anhydride.

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Lösungs- und Neutralisationswärmen von Lewis-Säuren und-Basen in Essigsäureanhydrid

Zusammenfassung Es wurden die Lösungswärmen einigerLewis-Säuren in Essigsäureanhydrid bestimmt und folgende Reihung nach ihrer relativen Stärke vorgeschlagen: SbCl₅>SO₃>SnCl₄>TiCl₄>AsCl₃ und Piperidin> n-Butylamin>KAc>NaAc-Picolin>Chinolin. Die Neutralisationswärmen dieserLewis-Säuren und-Basen legen nahe, daß der Hauptanteil daran auf die Reaktion eines Protons mit (CH₂–COOCOCH₃)-zurückzuführen ist.

     

Stabilization of platinum(II) hydrides by tri-t-butylarsine; facile syntheses of stable trans-PtH2[As(t-Bu)3]2 and trans-PtHX[As(t-Bu)3]2 complexes

trans-PtH₂[As(t-Bu)₃]₂ was prepared in very good yield by afacile reaction of K₂PtC1₄ with As(t-Bu)₃ in alkaline ethanol. Treatment of trans-PtH₂[As(t-Bu)₃]₂ with CF₃CO₂H or HCI afforded trans-PtH(O₂CCF₃)[As(t-Bu)₃]₂ or trans-PtHCl[As(t-Bu)₃]₂. respectively, in almost quantitative yield.     

Biligand metal chelates of 1,10-phenanthroline and several salicyclic acid derivatives in solution

Summary Mixed ligand complexes of copper(II), zinc(II), nickel(II) and cobalt(II) ions involving 1,10-phenanthroline (phen) as primary and 3,5-dinitrosalicylic acid (dnsa), 5-nitrosalicylic acid (nsa), 5-chlorosalicylic acid (csa) and 3,5-dibromosalicylic acid (dbsa) as secondary ligands in solution have been investigated potentiometrically [25°, µ = 0.1 M [NaClO₄], medium 50% v: v aqueous ethanol]. The stability order of mixed ligand complexes with respect to the metal ions obeys the natural order: cobalt(II) < nickel(II) < copper(II) > zinc(II). The stabilities of the heterometal chelates have been compared with the corresponding homometal chelates of the secondary ligands and have been interpreted in terms of metal-ligand effects and coulombic interactions between various ligand anion species present.     

Molybdenum complexes of bioinorganic interest. New dioxomolybdenum(VI) complexes of schiff bases derived from salicylaldehydes and salicylhydrazide

Summary New dioxomolybdenum(VI) complexes MoO₂L · H₂O (LH₂=Schiff base) derived from Salicylhydrazide and salicylaldehyde, 5-chloro-, 5-bromo-, 5-nitro-, 3-methoxy, 3-ethoxy-, 3,5-dichlorosalicylaldehyde and 2-hydroxy-1-naphthaldehyde have been synthesized and characterized, together with the MoO₂L · THF adducts. The complexes are monomers, nonelectrolytes and diamagnetic, and contain acis O=Mo=O     

Synthesis of polyhydroquinoline derivatives through unsymmetric Hantzsch reaction using organocatalysts

A novel and green approach for efficient and rapid synthesis of polyhydroquinoline derivatives via unsymmetric Hantzsch reaction using organocatalysts at room temperature was reported. The process is a simple, environmentally friendly, rapid, and high yielding reaction for the synthesis of polyhydroquinoline derivatives. The catalytic efficiency of various small organocatalysts such as l-proline, trans-4-hydroxy-l-proline, l-thiaproline, dl-phenylglycine, and (−)-cinchonidine was studied under aqueous, organic, and solvent free conditions.