Electrochemical synthesis of phosphorus esters from white phosphorus in the presence of copper complexes and ethanol

In the presence of white phosphorus the redox potentials of the copper ions change and the potential of the reduction wave of Cu^I/Cu⁰ shifts noticeably toward more positive values. The Cu^I—P₄ complex is characterized by a lower value of the electrochemical gap, that is, higher polarizability and reactivity compared to those of the free Cu^I cation. Phosphorus esters can be synthesized from P₄ and ethanol. The latter is in the composition of the copper(ii) complexes, which act as a catalyst-charge mediator.     

Electrochemical reduction of cobalt and nickel complexes with ligands stabilizing metal in low oxidation state

Electrochemical reduction of cobalt(ii) complexes containing -acceptor ligands (L = bpy, Ph₂Ppy) proceeds through three consecutive reversible steps: one-electron transfer to form a more stable Co^IL complex, transfer of two electrons at more negative potentials to form an anionic [NiL]^– complex, and reduction of the ligand to the radical anion. The stability of the cobalt complexes with different ligands decreases in the series Ph₂Ppy > Ph₃P > bpy.     

Kinetic Regularities of Electrochemical Reduction of Organic Halides under the Action of Cobalt Complexes with 2,2'-Bipyridine

Organic halides undergo electrocatalytic reduction under the action of coordinately unsaturated with respect to 2,2'-bipyridine (bipy) complexes Co^{+ 1}bipy (at the first wave potentials) and coordinately saturated complexes Co^{- 1}bipy₂ ^- (at the second wave potentials). The logarithms of the apparent rate constants logk _{a p p} decrease with increasing difference in the reduction potentials of substrate and catalyst E _p A-RX over a wide range of the motive forces of the process.     

Electrocatalytic reduction of organic halides with cobalt bipyridine complexes

The electrocatalytic reduction of organic halides by the [Nibpy]⁺complexes coordinationally unsaturated with bpy (at potentials of the first wave) and by the coordinationally saturated [Nibpy₂]^–complexes (at potentials of the second wave) was observed. The apparent rate constant of the process decreased with an increase in the difference of the reduction potentials of the substrate and catalyst in a large range of the driving force of the process.     

Reactions of 1-ethyl-1,2-diphosphole with acetylenes

Russian Chemical Bulletin - The cycloaddition of 1-ethyl-3,4,5-triphenyl-1,2-diphosphacyclopenta-2,4-diene to acetylenes R1C≡CR2 (R1 = R2 = CO2Me; R1 = Ph, R2 = H) gives phosphinine along...     

Activation of white phosphorus in the coordination sphere of nickel complexes with σ-donor ligands

Routes of white phosphorus activation in the coordination sphere of the nickel complexes with different ligands are shown. The first route is based on the coordination of a P₄ molecule with the metal, resulting in the deformation of the P₄ tetrahedron without destruction. This case is characteristic of the NiX₂L complexes, which are reduced at higher cathodic potentials (|E_red| > 0.9 V) (X = BF₄, Br, and Cl; L is bpy in DMF, MeCN, and acetone; 2,9-dimethyl-1,10-phenanthroline (phen) and PPh₃ in DMF and acetone). To cleave the P—P bonds in the P₄ molecule, this complex should be reduced on the electrode. The second route is the oxidation of white phosphorus in the coordination sphere of the Ni^II complex. It occurs when the complex has a sufficiently high oxidizing ability and is reduced rather easily (|E_red| < 0.9 V) (X = BF₄, L is 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) in acetone; 1,1′,5,5′-bis[methylenedi(p-phenylene)]di(3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) (n²p²) in DMF; phen and PPh₃ in MeCN). The P₄ molecule opening is observed to form a new Ni^I complex containing the (P₃) fragment, for example, [(triphos)Ni(P₃)Ni(triphos)](BF₄)₂. Dedicated to the Academician V. I. Minkin on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 919–924, April, 2005.     

Transformation of white phosphorus in the coordination sphere of nickel complexes with σ-donating ligands

Oxidation of white phosphorus in the coordination sphere of the nickel(ii) complex with 1,1,1-tris(diphenylphosphinomethyl)ethane and 1,1",5,5"-bis[methylenedi(p-phenylene)]di(3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) was shown to be possible and accompanied by the transformation of P₄ into the -P₃ ligand. The change in the nickel state was monitored by cyclic voltammetry, ³¹P NMR spectroscopy, ESR, and IR spectroscopy.