14637-34-4Relevant articles and documents
Dinitrogen coordination and cleavage promoted by a vanadium complex of a σ,π,σ-donor ligand
Vidyaratne, Indu,Crewdson, Patrick,Lefebvre, Emeric,Gambarotta, Sandro
, p. 8836 - 8842 (2008/10/09)
The deprotonation of the tripyrrole MeTPH2 [MeTPH2 = 2,5-[(2-pyrrolyl)(C6H5)2C] 2(MeNC4H2)], containing one N-methylated pyrrolyl ring, was carried out with 2 equiv of KH. The corresponding dipotassium salt reacted with VCl3(THF)3 to afford the complex [(MeTP)VCl(THF)]·THF (1). While the two lateral pyrrolide rings are σ-bonded, the central one is perpendicularly oriented in a sort of π-fashion. However, the bond distances clearly indicated that only the quaternized N atom is forming a bonding contact. Subsequent reduction of 1 with Na yielded the corresponding divalent complex [(MeTP)V(THF)]·(C 7H8)0.5 (2) where the central N-methylated ring adopted a more regular π-orientation. When treated with a strong Lewis acid (AlMe3), THF was extracted from the vanadium coordination sphere, forming the dinuclear dinitrogen complex [(MeTP)V(μ-N2)] 2·(C7H8)2.9 (3). Reduction of 3 with potassium graphite gave cleavage of dinitrogen, affording the mixed-valent nitride-bridged complex [(MeTP)V(μ-N)]2·(THF) (4).
Flame atomic absorption spectrometric determination of trace amounts of cobalt in standard alloys and biological samples after preconcentration of its 1,10-phenanthroline complex on tetraphenylborate - Microcrystalline naphthalene adsorbent
Taher,Puri
, p. 2963 - 2967 (2007/10/03)
A rapid, simple and sensitive method has been developed for determination of trace amount of cobalt using flame atomic absorption spectrometry. Cobalt is quantitatively retained as 1,10-phenanthroline-tetraphenylborate ion-associate complex on microcrystalline naphthalene in the pH range 2.6-9.5 from a large volume of its aqueous solutions of various standard alloys and biological samples. After filtration, the solid mass consisting of the cobalt complex and naphthalene is dissolved in 5 mL of dimethylformamide (DMF) and the metal is determined using flame atomic absorption spectrometry by measuring the absorbance at 240.7 nm. Cobalt-1,10-phenanthroline complex can alternatively be quantitatively retained on ammonium tetraphenylborate-naphthalene adsorbent packed in a column at a flow rate of 2 mL/min under the same conditions and determined similarly. In this case, 1.0 μg of cobalt is concentrated in a column from 400 mL of its aqueous sample, where its concentration is as low as 2.5 ppb. Eight replicate determinations of 4.0 ppm cobalt gives a mean absorbance of 0.120 with a relative standard deviation of 1.8%. The sensitivity for 1% absorption is 147 ppb. The conditions have been optimized and utilized for trace determination of cobalt in various standard samples.
The libration-vibration bands of the ammonium ion in ammonium tetraphenylborate: Evidence for nearly free rotation
Roberts, Malcolm P.,Clavell-Grunbaum, Dolores,Strauss, Herbert L.
, p. 6393 - 6405 (2007/10/02)
The N-H stretching and H-N-H bending regions of the infrared spectrum of the title compound (ATPB) have been examined with care. The stretching bands show rotation-like structure that we attribute to rotational motion of NH 4+ in a very low barrier. The barrier has the symmetry of a tetrahedral molecule in a tetrahedral site and is characterized by the dimensionless parameter β=1. The J=0 and J=1 levels are below the barrier and the J=2 levels are above it. Slow interconversion of nuclear spin species is seen in keeping with the low barrier model. The spectra of the ATPB with some NH3D+, with a high concentration of K+ and with deuterated phenyl groups have been examined, and show spectra in keeping with the model.
