Dissociation kinetics of metal complexes in aqueous acid. III. The effects of methyl substitution and chelate ring size on the rates of dissociation of copper(II) triazamacrocyclic complexes

1984 ◽  
Vol 37 (11) ◽  
pp. 2243 ◽  
Author(s):  
PG Graham ◽  
DC Weatherburn
Keyword(s):  
Chelate Ring ◽  
Acid Dissociation ◽  
Ring Size ◽  
Dissociation Kinetics ◽  
Methyl Substitution ◽  
First Order ◽  
Aqueous Acid ◽  
Kinetics Of ◽  
Chelate Ring Size ◽  
Acid Dependence

The acid dissociation kinetics of mono copper(II) complexes of the ligands 2-methyl-1,4,7-triazacyclononane, mznn ; 1,4,7-triazacycloundecane, zaud ; 1,4,7-triazacyclododecane, zadd ; and 1,5,9-triazacyclotetradecane, zted were studied in aqueous solution over a range of acid concentra- tions (0.025-0.5 mol 1-1), I1.0 (NaN03). Cu(mznn)2+ displays a first-order dependence on [H+] with kH (298 K) 26 1. mol-1 s-1. The other complexes show an acid dependence at low [H+] but become independent of acid at higher concentrations. The acid-independent rate constants k1 were determined to be Cu(zaud)2+, 67 s-1 (280 K); Cu(zadd)2+, 45 s-1 (298 K); Cu(zted)2+ 50 s-1 (298 K). The results are compared with those obtained with other copper(II) triazamacro- cyclic complexes.

Dissociation kinetics of metal complexes in acid. Copper complexes of triazamacrocycles

1981 ◽  
Vol 34 (2) ◽  
pp. 291 ◽  
Author(s):  
PG Graham ◽  
DC Weatherburn
Keyword(s):  
Aqueous Solution ◽  
Copper Complexes ◽  
Activation Parameters ◽  
Macrocyclic Complex ◽  
Acid Dissociation ◽  
General Mechanism ◽  
Dissociation Kinetics ◽  
First Order ◽  
High Concentrations ◽  
Kinetics Of

The acid dissociation kinetics of the mono-copper complexes of 1,4,7-triazacyclononane, znn; 1,4,7-triazacyclodecane, zdn; 1,4,8-triazacycloundecane, zud; 1,5,9-triazacyclododecane, zdd; 2,2,4-trimethyl-1,5,9-triazacyclododecane, tmzdd; 1,5,9-triazacyclotridecane, ztd; and cyclohexane- r-1,c-3,c-5 triamine, ccha, were studied in aqueous solution over a range of acid concentrations (0.025-0.5 mol dm-3), I 1.0 (NaN03). A variety of kinetic behaviour is observed. Cu(znn)2+, Cu(zdn)2+ and Cu(zud)2+ display a first-order dependence upon [H+] with kH (298 K) 51 dm3 mol-1 s-1 (znn), 17 dm3 mol-1 s-1 (zdn), and 5.6 dm3 mol-1 s-1 (zud). Cu(zdd)2+, Cu(ztd)2+ and Cu(ccha)2+ show a dependence on [H+] at low acid concentrations but become acid-independent at high concentrations. The acid-independent rate constants are k1 (298 K) 2.2 s-1 (zdd), 15.4 s-1 (ztd) and k1 (283 K) 75 s-1 (ccha). Cu(tmzdd)2+ shows a rate law of the form rate = k+kH[H+] with k (298 K) 1.8×10 s-1 and kH (298 K) 2.0×10-3 dm3 mol-1 s-1. Activation parameters have been determined in all cases except Cu(ccha)2+ which was studied at 10�C. The results are compared with other macrocyclic complex systems, and a general mechanism for these reactions is discussed.

Di- and trimethylplatinum(IV) complexes with aspartate: some subtle effects of chelate ring size

Polyhedron ◽  
1995 ◽  
Vol 14 (19) ◽  
pp. 2613-2622 ◽  
Author(s):  
Trevor G. Appleton ◽  
John R. Hall ◽  
Trevor G. Jones ◽  
Jacqueline A. Sinkinson
Keyword(s):  
Chelate Ring ◽  
Ring Size ◽  
Chelate Ring Size

Influence of chelate ring size on the properties of phosphine-sulfonate palladium catalysts

2018 ◽  
Vol 61 (9) ◽  
pp. 1175-1178 ◽  
Author(s):  
Chen Zou ◽  
Wenmin Pang ◽  
Changle Chen
Keyword(s):  
Palladium Catalysts ◽  
Chelate Ring ◽  
Ring Size ◽  
Chelate Ring Size

The comparative chemistry of ammine and methylamine complexes of rhodium(III) and cobalt(III)

1977 ◽  
Vol 55 (17) ◽  
pp. 3166-3171 ◽  
Author(s):  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Spectral Data ◽  
Electron Donor ◽  
Dissociation Constants ◽  
Base Hydrolysis ◽  
Acid Dissociation ◽  
Rate Coefficients ◽  
Acid Dissociation Constants ◽  
First Order ◽  
Kinetics Of

For the aquation of (CH3NH2)5RhCl2+, the first order rate coefficients are represented by ΔHaq* = 101.9 kJ mol−1 and ΔSaq* = −50.2 JK−1 mol−1 in 0.1 M HClO4, while for base hydrolysis the rate is first order in [(CH3NH2)5RhCl2+] and [OH−] at ionic strength 0.10 M and the rate coefficients (in M−1 s−1) are represented by ΔHOH*> = 108.6 kJ mol−1 and ΔSOH* = 74.1 J K−1 mol−1. Acid dissociation constants are reported for (RNH2)5MOH23+ (R = H or CH3; M = Rh or Co), and these, combined with spectral data, show CH3NH2 to be a poorer electron donor than NH3 in complexes of this type, contrary to expectations. The comparative kinetics of reactions of (RNH2)5MCl2+ support the assignment of an Ia mechanism to aquation when M = Rh or Cr, Id to aquation when M = Co, and Dcb for base hydrolysis in all these cases.

Chelate Ring Size Effect on the Reactivity of [2-(2-Phenyl-5,6-dihydro-4H-1,3-oxazinyl)]lithium and Se···N Interactions in Low-Valent Organoselenium Compounds:  Facile Isolation of Diorganotriselenide

2004 ◽  
Vol 23 (18) ◽  
pp. 4199-4208 ◽  
Author(s):  
Sangit Kumar ◽  
Karuppasamy Kandasamy ◽  
Harkesh B. Singh ◽  
Gotthelf Wolmershäuser ◽  
Ray J. Butcher
Keyword(s):  
Size Effect ◽  
Chelate Ring ◽  
Ring Size ◽  
Organoselenium Compounds ◽  
Low Valent ◽  
Chelate Ring Size
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