Reactions of Lithium Salts of Triphosphanes tBu2P–PLi–PtBu2 and tBu2P–PLi–P(NEt2)2 with Metal Complexes [(R3P)2MCl2] (M = Ni,Pd, Pt,R3P = Et3P,pTol3P,Ph2EtP,iPr3P)

tBu₂P–PLi–PtBu₂ · 2THF reacts with [(R₃P)₂MCl₂] (M = Pt, Pd, Ni; R₃P = Et₃P, pTol₃P, Ph₂EtP, iPr₃P) to yield isomers of [(1,2‐η‐tBu₂P=P–PtBu₂)M(PR₃)Cl], in which the tBu₂P–P–PtBu₂ ligand adopts the arrangement of a side‐on bonded 1,1‐di‐tert‐butyl‐2‐(di‐tert‐butylphosphanyl)diphosphenium cation. tBu₂P–PLi–P(NEt₂)₂ · 2THF reacts with [(R₃P)₂MCl₂] but does not form complexes with a tBu₂P–P–P(NEt₂)₂ moiety, however, splitting of a P–P(NEt₂)₂ bond of the parent triphosphane takes place.     

A Study of the Lipophilicity of Amide Derivatives of α-(1,2,3,4-Tetrahydroisoquinolin-2-yl)-γ-hydroxybutyric Acid by Use of RP-TLC and Calculation

JPC – Journal of Planar Chromatography – Modern TLC - Evaluation of the lipophilicity of derivatives of N-benzylamides and N-phenylethylamides of...     

Electronegativity force of cations and thermal decomposition of complex fluorides

The thermal decompositions of anhydrous fluorosilicates M₂SiF₆ (M=Li, Na, K, Rb, Cs) and MSiF₆ (M=Ca, Sr, Ba) were investigated. The decompositions proceeded according to a simple acid-base mechanism with evolution of SiF₄. The influence of the cationic counter-ion acidity (expressed by means of the electronegativity force) on the course of thermal decomposition was estimated quantitatively.     

Chemical processes in kaolin sintered with NaH2PO4

The results of experiments on application of NaH₂PO₄ as a binding agent for ceramic kaolin samples were presented. The experiments were carried out at temperatures of 973, 1073 and 1173 K and NiO and CoO additives were used as tempering agents. The parameters of the obtained samples with NaH₂PO₄ were compared with the samples compressed with water only. The materials of 3-4 times higher bending strength, lower water absorption as well decreased open porosity were prepared during these experiments. The binding function of the NaH₂PO₄ additive relies on creation of some compounds in reaction between the products of its condensation and products of kaolin decomposition. Finally a ceramic material of prospective properties was created. This revised version was published online in July 2006 with corrections to the Cover Date.     

The potential dependence and kinetics of HCOOH adsorption on rhodium electrodes

The formic acid adsorption on an electrochemically prepared rhodium electrode has been studied by the radiochemical method. Electrochemical properties of the rhodium electrode surface in 0.5 M H₂SO₄ have been investigated by cyclic voltammetry. It has been shown that starting from E=0.20 V the rate of HCOOH adsorption is markedly potential dependent being practically independent of the electrode potential up to E=0.20 V. It seems that the HCOOH adsorption process may be explained on the basis of the two-sites kinetics model. The data obtained for HCOOH adsorption on a rhodium electrode have been compared with those for a platinum electrode reported previously.     

Kinetics and mechanism of the base hydrolysis of cis-eq-[Cr(NCS)(S-pdtra)]−, trans-eq-[Cr(NCS)(edtrp)]− and trans-eq-[Cr(NCS)(R-pdtrp)]− complexes. Strong rate enhancement for NCS− ligand release with an increase of [OH−] only for the trans-equatorial isomers

The [Cr(NCS)(edtrp)]⁻, [Cr(NCS)(R-pdtrp)]⁻ and [Cr(NCS)(S-pdtra)]⁻ complexes, that are derivatives of the trans-equatorial isomers of [Cr(edtrp)(H₂O)]° and [Cr(R-pdtrp)(H₂O)]° and the cis-equatorial isomer of [Cr(S-pdtra)-(H₂O)]° (edtrp = ethylenediamine-N,N,N′-tripropionate, R-pdtrp = R-propane-1,2-diamine-N,N,N′-tripropionate, S-pdtra = S-propane-1,2-diamine-N,N,N′-triacetate) undergo aquation in alkaline media with a strong dependence of the rate on [OH⁻] for the trans-equatorial isomers and a very weak dependence for the cis-equatorial isomer. The thiocyanate ligand release follows a stereoretentive course for all reactants. Based on kinetic data the reaction mechanism has been discussed. Rate differences between the isomers are interpreted in terms of an interchange via a conjugate base (I c.b.) mechanism, assuming an equilibrium between the cis-equatorial-Cr^III-S-pdtra complexes with penta- and tetradentate coordination of the edta-like ligand. This revised version was published online in June 2006 with corrections to the Cover Date.     

Tricarbonylcyclohexadienyliumiron Complexes in the Synthesis of 2-Azaspiro[5.5]undecane System with Tunable Amide

Excellent regio- and stereoselectivity during nitrile addition to dienylium-Fe(CO)(3) can be achieved with perchlorate salts, allowing the preparation of the 1-oxo- and 3-oxo-2-azaspiro[5.5]undecane ring systems. The phthalimide complex 2 was prepared in high yield by Mitsunobo reaction.