Octahedral cobalt(III) complexes in dipolar aprotic solvents. V. The substitution of chloride and thiocyanate into the cis-chlorodimethylformamidebisethylenediaminecobalt(III) ion in anhydrous NN-dimethylformamide

1966 ◽  
Vol 19 (6) ◽  
pp. 949 ◽  
Author(s):  
IR Lantzke ◽  
DW Watts
Keyword(s):  
Chloride Ion ◽  
Ion Pair ◽  
Kinetics And Mechanism ◽  
Aprotic Solvents ◽  
Dissociative Mechanism ◽  
Thiocyanate Ion ◽  
Dipolar Aprotic Solvents ◽  
Chloride Concentrations

The kinetics and mechanism of the substitution of chloride ion and thiocyanate ion into the cis-chlorodimethylformamidebisethylenediaminecobalt(111) ion, cis-[CoCl(DMF) en2]2+, have been studied in ,NN-dimethylformamide (DMF). The chloride entry shows mixed kinetics which are accounted for by two paths, a slow ion pair dissociation, and a fast bimolecular attack of chloride on an ion pair. The steric course of the reaction, which is chloride dependent, shows that the ion pair dissociative mechanism is more important at low chloride concentrations. The thiocyanate entry shows similar characteristics. Thiocyanate enters faster than chloride in the bimolecular path, but in the ion pair dissociative path, which is significant at lower anion concentration, both chloride and thiocyanate enter at the same rate.

Octahedral cobalt(III) complexes in dipolar aprotic solvents. I. The substitution of thiocyanate into the cis-Chlorodimethylsulphoxidobisethylenediaminecobalt(III) ion in anhydrous dimethylsulphoxide and NN-dimethylformamide

1965 ◽  
Vol 18 (4) ◽  
pp. 453 ◽  
Author(s):  
LF Chin ◽  
WA Millen ◽  
DW Watts
Keyword(s):  
Activation Energy ◽  
Ion Pair ◽  
Second Order ◽  
Aprotic Solvents ◽  
Kcal Mole ◽  
Dissociative Mechanism ◽  
Thiocyanate Ion ◽  
First Order ◽  
Rate Determining Step ◽  
Dipolar Aprotic Solvents

The substitution of thiocyanate ion into the cis-chlorodimethylsulphoxidobisethylenediaminecobalt(III) ion, cis-(Coen2(DMSO)Cl)2+, has been studied in the solvents dimethylsulphoxide (DMSO) and NN-dimethylformamide (DMF). In DMSO the reaction shows second-order characteristics which are accounted for by an ion-pair dissociative mechanism (SNIIP). The activation energy is 30.1 kcal mole-1. In DMF the entry is first-order, the rate determining step being solvolysis to the intermediate cis-(Coen2(DMF)Cl)2+ which has been isolated as the nitrate. In high thiocyanate concentrations the rate shows some thiocyanate dependence due to the competition of ion-paired thiocyanate with the DMF solvent for coordination following the DMSO dissociation. The activation energy for this substitution is 17.5 kcal mole-1.

Octahedral chromium(III) complexes in dipolar aprotic solvents. I. The isomerization of cis- and trans-Dichlorobisethylenediamine-chromium (III) ions in anhydrous NN-dimethylformamide

1967 ◽  
Vol 20 (1) ◽  
pp. 53 ◽  
Author(s):  
DA Palmer ◽  
DW Watts
Keyword(s):  
Activation Parameters ◽  
Chloride Ion ◽  
Kinetics And Mechanism ◽  
Significant Part ◽  
Aprotic Solvents ◽  
Free Chloride ◽  
System Activation ◽  
Cis And Trans ◽  
Dipolar Aprotic Solvents

The kinetics and mechanism of the isomerization of cis- and trans- dichloro- bisethylenediaminechromium(III) ions, cis- and trans-[CrCl2 en2]+, have been investigated in anhydrous NN-dimethylformamide (DNF). The complex cis- chlorodimethylformamidebisethylenediaminechromium- (III), cis-[CrCl(DMF) en2]2+, is found to be a necessary intermediate and to remain a significant part of the system at equilibrium. The equilibria are found to depend on the concentration of free chloride ion as has been found in the comparable cobalt system.��� Activation parameters have been determined for isomerization reactions using both the cis- and trans-(CrCl2 en2)+ ions as starting materials and for the chloride entry reaction into the cis-[CrCl(DMF) en2]2+ ion which has been isolated as cis-[CrCl(DMF) en2](ClO4)2,R2O.

Octahedral cobalt(III) complexes in dipolar aprotic solvents. II. Association between cis- and trans-dichlorobisethylenediamine cobalt(III) cations,[Co en2 Cl2]+, and chloride and bromide ions in the solvents NN-dimethylformamide, dimethyl sulphoxide, and LVN-dimethylacetamide

1966 ◽  
Vol 19 (1) ◽  
pp. 43 ◽  
Author(s):  
WA Millen ◽  
DW Watts
Keyword(s):  
Spectrophotometric Method ◽  
Ion Pairs ◽  
Ion Association ◽  
Ion Pair ◽  
Association Constants ◽  
Dimethyl Sulphoxide ◽  
Aprotic Solvents ◽  
Ion Association Constants ◽  
Cis And Trans ◽  
Dipolar Aprotic Solvents

Ion association constants at 30� have been determined for the cis-[Co en, Cl2]+Cl- ion pair in NN-dimethylformamide (DMF), NN-dimethylacetamide (DMA), and at 20.0�, 25.0�, and 30.0� in dimethyl sulphoxide (DMSO), by a spectrophotometric method. Association constants for the cis-[Co en2 Cl2]+Br- and the trans- [Co en2 Cl2]+Cl- ion pairs have also been determined in DMF at 30�.

Ion-pair effects on the electroreduction and electrochromic properties of ortho-chloranil in dipolar aprotic solvents

1987 ◽  
Vol 216 (1-2) ◽  
pp. 203-212 ◽  
Author(s):  
A. Desbene-Monvernay ◽  
P.C. Lacaze ◽  
J.-E. Dubois ◽  
A. Cherigui
Keyword(s):  
Ion Pair ◽  
Aprotic Solvents ◽  
Electrochromic Properties ◽  
Dipolar Aprotic Solvents

Octahedral cobalt(III) complexes in dipolar aprotic solvents. IV. Solvolysis and isomerization of dibromobisethylenediaminecobalt(III) ions inanhydrous NN-dimethylformamide and NN-dimethylacetamide

1966 ◽  
Vol 19 (6) ◽  
pp. 935 ◽  
Author(s):  
WR Fitzgerald ◽  
DW Watts
Keyword(s):  
Concentration Dependence ◽  
Ion Association ◽  
Ion Pair ◽  
Aprotic Solvents ◽  
Equilibrium System ◽  
Lower Stability ◽  
Bromide Ion ◽  
Cis And Trans ◽  
Dipolar Aprotic Solvents

The equilibrium system (SOL)+Br-+cis-[CoBr2 em]+ = cis-[CoBr(SOL) en2]2++2Br-   =trans[CoBr2en2]2++Br-+SOL where SOL represents either of the solvents NN-dimethylformamide (DMF) or NN-dimethylacetamide (DMA), has been studied. The compounds cis- [CoBr(DMF) en2](ClO4)2, and cis-[CoBr(DMA) en2]XO3,ClO4, have been isolated and thus it has been possible to study these equilibria using as starting materials both the cis- and trans-dibromo complexes (cis- and trans-[CoBr2 en2]+) and the solvento complexes (cis-[CoBr(DXA) en2]2+ and cis-[CoBr(DMF) en2]2+). The mechanism of the bromide entry reactions cis-[CoBr(SOL) en2]2+ +Br- = cis- and trans-[CoBr2 en2]++SOL is bimolecular in DMA while in DMF the reaction is dissociative: the rate showing bromide concentration dependence only in the concentration range where ion association is not complete. In both systems the isomerization proceeds mainly through the solvento complex; in dimethylacetamide there is evidence for a seven-coordinated intermediate. The isomerization equilibria are found to be bromide concentration dependent, cis-[CoBr2 en2]+ being favoured by high bromide concentrations. This is consistent with the lower stability of the trans-[CoBr2 en2]- ion pair with bromide ion.

Octahedral chromium(III) complexes in dipolar aprotic solvents. II. The isomerization of cis- and trans-[CrCl2 en2]+ ions in anhydrous dimethyl sulphoxide

1968 ◽  
Vol 21 (12) ◽  
pp. 2895 ◽  
Author(s):  
DA Palmer ◽  
DW Watts
Keyword(s):  
Ion Association ◽  
Chloride Ion ◽  
Activation Energies ◽  
Dimethyl Sulphoxide ◽  
Aprotic Solvents ◽  
Ion Concentrations ◽  
Cis And Trans ◽  
Dipolar Aprotic Solvents ◽  
Exchange Data

The equilibria represented by the following equations: (See diagram in paper) have been studied in anhydrous dimethyl sulphoxide at various chloride ion concentrations. The mechanisms of the reactions are interpreted as dissociative and this assignment is consistent with the radiochloride exchange data. The kinetic and equilibria results are dependent on ion association which is separately treated by conductance measurements in the case of cis-[CrCl2 en2]+Cl-. Activation energies are recorded.

Chloride-ion promoted dehydrochlorination of 1,1-diaryl-2,2,2-trichloroethanes in dipolar aprotic solvents

1972 ◽  
pp. 2308 ◽  
Author(s):  
O. R. Jackson ◽  
D. J. McLennan ◽  
S. A. Short ◽  
R. J. Wong
Keyword(s):  
Chloride Ion ◽  
Aprotic Solvents ◽  
Dipolar Aprotic Solvents
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