Chromium(III) complexes in dipolar aprotic solvents. VIII. Solvolysis of hexaisothiocyanatochromate(III) and solvent exchange, substitution and anation of the pentaisothiocyanato(solvento)chrornate(III) complex, [Cr(NCS)5(sol)]2-

1975 ◽  
Vol 28 (9) ◽  
pp. 1907 ◽  
Author(s):  
STD Lo ◽  
DW Watts
Keyword(s):  
Activity Coefficients ◽  
Transition States ◽  
Aprotic Solvents ◽  
Solvent Exchange ◽  
Dissociative Mechanism ◽  
Transfer Activity ◽  
Activation Data ◽  
Dipolar Aprotic Solvents ◽  
Interchange Reactions ◽  
Solvent Transfer

The displacement of the coordinated Me2SO from [Cr(NCS)5(Me2SO)]2- by NCS- and pyridine has been studied in the solvent tetramethylene sulphone (sulpholane). The results are consistent with a limiting dissociative mechanism. The solvolysis reactions: �� ��������������[Cr(NCS)6]3- + sol → [Cr(NCS)5(sol)]2- + NCS- have been studied in the solvents (sol) Me2SO, HCONMe2 and MeCONMe2. The transition states for these solvolysis reactions are compared with a dissociative model ������������������������ [Cr(NCS)5(3-)+(∂+)...NCS∂-] by means of solvent transfer activity coefficients. Kinetic and activation data are recorded for a number of solvent interchange reactions: ����������� [Cr(NCS)5(sol1)]2- + sol2 → [Cr(NCS)5(sol2)]2- + sol1

Transfer activity coefficients between some dipolar aprotic solvents and alcohols of salts composed of various anions and potassium complexed with Bis(4,4'(5')-t-butylbenzo)-18-crown-6

1983 ◽  
Vol 36 (9) ◽  
pp. 1753 ◽  
Author(s):  
Jr MK Chantooni ◽  
IM Kolthoff ◽  
G Roland
Keyword(s):  
Dimethyl Sulfoxide ◽  
Stability Constants ◽  
Propylene Carbonate ◽  
Activity Coefficients ◽  
Isopropyl Alcohol ◽  
The Other ◽  
Aprotic Solvents ◽  
Transfer Activity ◽  
Dipolar Aprotic Solvents

Stability constants, Kf(LK+) and Kf(LKX) = [LKX]/[L][KX] at 25� in the dipolar aprotic solvents acetone (Me2CO), acetonitrile (MeCN), propylene carbonate (pc), N,N-dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO), as well as in the alcohols, methanol (MeOH), isopropyl alcohol (Pr1OH), and butan -1-ol (BuOH) have been determined, L being bis(4,4'(5')-t-buty1benzo)-18- crown-6 (di(BuBo)-18-cr-6). This crown is considerably more lipophylic than is dibenzo-18-crown-6. Values of Kf(LKX) have been found from values of Kf(LK+), KA(KX) and KA(LKX). Transfer activity coefficients, Me2COγS, have been calculated (based on the Parker proposal that γ(Ph4As+) = γ(BPh4-) between acetone and the various solvents used of K+, Br-, ClO4-, P1- (picrate), LK+, KX, and LKX. It is found that K+ is more strongly solvated in Me2CO than in the other aprotic solvents of low donicity. The reverse is true between Me2CO and HCONMe2 or Me2SO (even after correcting for the Born effect).

Estimation of transfer activity coefficients for single ions between dipolar aprotic solvents from the E.M.F. of cells with liquid junction

1983 ◽  
Vol 36 (9) ◽  
pp. 1767 ◽  
Author(s):  
SS Goldberg ◽  
O Popovych
Keyword(s):  
Activity Coefficients ◽  
Salt Bridge ◽  
Aprotic Solvents ◽  
Liquid Junction ◽  
Transfer Activity ◽  
Novel Method ◽  
Glass Electrodes ◽  
Tetraethylammonium Perchlorate ◽  
Dipolar Aprotic Solvents ◽  
Junction Potential

Transfer activity coefficients for the sodium ion, logmγNa, between pairs of dipolar aprotic solvents were estimated from the e.m.f. of cells consisting of two sodium-selective electrodes in different solvents connected by a salt-bridge of triisoamylbutylammonium tetraphenylborate [(tab+)BPh4-], or tetraethylammonium picrate (Et4NPic), or tetraethylammonium perchlorate (Et4NclO4). The solvents were: acetonitrile (MeCN), N,N-dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO), propylene carbonate (pcar), and N-methylformamide (HCONHMe). Values of logmγNA were estimated first by neglecting the liquid-junction potential E, and then, for some systems, by applying an Ej correction from theory. A novel method of estimating transfer activity coefficients for single ions, based on the Ej equation, was demonstrated on the (tab+) and Pic-ions. Transfer activity coefficients for the hydrogen ion between MeCN and HCONMe2 as well as MeCN and Me2SO were similarly estimated from the e.m.f. of two pH (glass) electrodes immersed in buffer media in the above pairs of solvents.

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.

Chromium(III) complexes in dipolar aprotic solvents. VI. The anation of Hexa(dimethyl sulphoxide)chromium(III) [Cr(Me2SO)6]3+ in dimethyl sulphoxide

1975 ◽  
Vol 28 (3) ◽  
pp. 491 ◽  
Author(s):  
STD Lo ◽  
DW Watts
Keyword(s):  
Ionic Strength ◽  
Dimethyl Sulphoxide ◽  
Aprotic Solvents ◽  
Analogous Reaction ◽  
Dipolar Aprotic Solvents ◽  
Interchange Reactions

The anation reactions: �������������������� Cr(Me2SO)63+ + X- → CrX(Me2SO)52+ + Me2SO have been studied in detail for X- = N3- and SCN- as a function of concentration, temperature and ionic strength in both conditions of X- in excess over Cr(Me2SO)63+, and Cr(Me2SO)63+ in excess over X-, where greater certainty exists concerning the nature of the solution species. The reactions are interpreted as dissociative interchange reactions in which anation is a probable result of dissociation only when the anion occupies a position in the first solvation sphere of the complex. ��� Less complete results are presented for the less tractable anation of Cr(Me2SO)63+ by Cl- in Me2SO, and the analogous reaction of Cr(HCONMe2)63+ by Cl- in dimethylformamide.

A New Method for the Estimation of Transfer Activity Coefficients of Ions From the E.M.F. of Cells With Liquid Junction

1988 ◽  
Vol 41 (10) ◽  
pp. 1523 ◽  
Author(s):  
A Berne ◽  
O Popovych
Keyword(s):  
Concentration Dependence ◽  
Activity Coefficients ◽  
Salt Bridge ◽  
Liquid Junction ◽  
Transfer Activity ◽  
Liquid Junction Potentials ◽  
Solvent Component ◽  
Calculated Liquid ◽  
Dipolar Aprotic Solvents ◽  
Junction Potential

Transfer activity coefficients of the tetraalkylammonium ions, logmγR, where R+ = Me4N+, Et4N+, Pr4N+ and Bu4N+, and of the picrate ion, logmγPic, between pairs of dipolar aprotic solvents, S1 → S2, were evaluated by combining the e.m.f . of cells Ag(cryst.)|AgClO4|RX|AgClO4|Ag( cryst .)�������������������������������� S1 ������ S2with the calculated liquid-junction potentials, Ej. The salt-bridge electrolyte RX was RClO4 and R Pic for the determinations of logmγR and logmγPic, respectively, and the solvents were: acetonitrile ( MeCN ), N,N- dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO) and propylene carbonate ( pcar ). The logmγR values showed a systematic variation with the AgClO4 concentration, apparently caused by the concentration dependence of the solvent component of the liquid-junction potential, Ej,s, neglected in the calculations. However, the above concentration dependence was virtually eliminated from the values of logmγPic when they were calculated with the aid of our concentration-dependent logmγR data. For a number of our cells it was possible to evaluate the Ej,s, with the aid of literature data. The solvent component of Ej was found to be appreciable and varied both with the AgClO4 and the RX concentration. The Ej,s, was particularly large for cells containing pcar , with a maximum of -172 mV for the pcar | MeCN junction.

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