scispace - formally typeset
Search or ask a question
Topic

Aquation

About: Aquation is a research topic. Over the lifetime, 1443 publications have been published within this topic receiving 17507 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: A monotonic increase in the extinction coefficient is observed on going from the cyclam complexes to the 1,11-C3-cyclam complexes, and this is related to the degree of centrosymmetry in each complex.
Abstract: The synthesis and characterization of several Cr(III) complexes of the constrained macrocyclic ligand 1,11-C3-cyclam (1,4,8,11-tetraazabicyclo[9.3.3]heptadecane) is reported. Only trans complexes are formed, and the structure of trans-[Cr(1,11-C3-cyclam)Cl2]PF6 is presented. The chemical and photophysical behavior of the 1,11-C3-cyclam complexes are compared with those of the corresponding cyclam (1,4,8,11 tetraazacyclotetradecane) and 1,4-C2-cyclam (1,4,8,11-tetraazabicyclo[10.2.2]hexadecane) complexes. The aquation rate of trans-[Cr(1,11-C3-cyclam)Cl2]+ is similar to that of the corresponding 1,4-C2-cyclam complex and is more than 5 orders of magnitude faster than the cyclam counterpart. A monotonic increase in the extinction coefficient is observed on going from the cyclam complexes to the 1,11-C3-cyclam complexes to the 1,4-C2-cyclam complexes, and this is related to the degree of centrosymmetry in each complex. The trans-[Cr(1,11-C3-cyclam)(CN)2]+ complex is a weak emitter in aqueous solution with a room-temperature emission maximum at 724 nm (tau=23 micros). Like the corresponding 1,4-C2-cyclam complex (tau=0.24 micros), the 1,11-C3-cyclam complex shows no deuterium-isotope effect in room-temperature solution. This is in marked contrast to the corresponding cyclam complex which has an emission lifetime of 335 micros and a significant deuterium isotope effect in room-temperature solution. Low temperature (77K) data are also presented in an attempt to understand the differences in photophysical behavior.

18 citations

Journal ArticleDOI
Abstract: Kinetics and equilibria for reversible formation of 1:1 monodentate complexes between Pd(H2O)42+ and acetic, propionic, and glycolic acid (RCOOH) according to the equation Pd(H2O)42+ + RCOOH ⇌ Pd(H2O)3OOCR+ + H3O+ (k1, k-1) have been studied as a function of temperature and pressure in an aqueous medium with 0.60 ≤ [H+] ≤ 1.00 M, [RCOOH]/[H+] ≤ 1.0, and ionic strength 1.00 M. Stability constants β1 for the formation of acetate, propionate, and glycolate complexes are (2.19 ± 0.09) × 104, (2.10 ± 0.24) × 104, and (6.4 ± 0.1) × 103 M-1, repectively, at 25 °C and for a 1.00 M perchlorate medium. The rate expression, kobsd = k1[RCOOH] + k-1[H+], indicates that reaction between palladium and carboxylate anions is negligible under the experimental conditions used. Values for k1/M-1 s-1, k-1/M-1 s-1, ΔH1⧧/kJ mol-1, ΔH-1⧧/kJ mol-1, ΔS1⧧/J K-1 mol-1, ΔS-1⧧/J K-1 mol-1, ΔV1⧧/cm3 mol-1, and ΔV-1⧧/cm3 mol-1 at 25.0 °C are 19.3 ± 0.6, 32.8 ± 0.2, 52.5 ± 0.4, 57.5 ± 0.4, −44 ± 1, −23 ± 1, −8.1 ± 0.3, and −1.7 ± 0.2 for...

18 citations

Journal ArticleDOI
TL;DR: In this paper, a number of new diphosphine complexes of cobalt(III), trans- and cis-[CoCl2(dmpe, dmpp, dbpe, or dpee)2]+ have been prepared and characterized.
Abstract: A number of new diphosphine complexes of cobalt(III), trans- and cis-[CoCl2(dmpe, dmpp, dbpe, or dpee)2]+, trans- and cis-[CoBr2(dmpe)2]+, trans- and cis-[CoCl(H2O)(dmpe)2]2+, trans-[Co(I2 or BrI)(dmpe)2]+, and [Co(CO3)(dmpp or dbpe)]+ have been prepared and characterized, where dmpe, dmpp, dbpe, and dpee denote 1,2-bis(dimethylphosphino)ethane, 1,3-bis(dimethylphosphino)propane, 1,2-bis(dibutylphosphino)ethane, and cis-1,2-bis(diphenylphosphino)ethylene, respectively. The trans isomers of the dihalogeno complexes are stable to aquation, while the cis isomers release one of the halide ions in water fairly rapidly to yield cis-[CoX(H2O)(diphosphine)2]+ which isomerizes to the trans isomer on exposure of ultraviolet light. The cis-[CoCl2(diphosphine)2]+ complexes in methanol or ethanol solution isomerize to the trans isomer, and the rates were followed spectrophotometrically in the temperature range of 39.0–65.0 °C. The rates have a first-order dependence on the complex concentration. Both the ΔH\eweq and Δ...

17 citations

Journal ArticleDOI
TL;DR: In this article, the photochemical decomposition of dilute HCl, HClO4 and H2SO4 solutions has been studied and the yield of each species as a function of the time of uv irradiation was determined.
Abstract: The photochemical decomposition of (NH4)2TcCl6 in dilute HCl, HClO4 and H2SO4 solutions has been studied. Electrophoresis and spectrophotometry were used to identify TcCl 6 2− , TcCl5 (H2O)−, cationic and uncharged species and TcO 4 − . The yield of each species as a function of the time of uv irradiation was determined. The TcCl 6 2− , yield decreases to zero after 50 h of irradiation. The TcCl5(H2O)−, cationic and uncharged species and TcO 4 − are formed in different proportions in the three acids. After 120 h of irradiation of the HCl solution the principal Tc species was the cationic one (≈70%) followed by the uncharged species (≈24%). In HClO4 solution the cationic species (≈70%) was followed by TcO 4 − , but in H2SO4 solution the uncharged species amounts to ≈90%.

17 citations

Journal ArticleDOI
TL;DR: In this paper, the rates of release of fiuoride by acid and base hydrolysis of cis-STACr(en)/sub 2/F/ sub 2/O)F!/sup 2+/ were determined over a range of pH 1 to 8.
Abstract: The rates of release of fiuoride by acid and base hydrolysis of cis- STACr(en)/sub 2/F/sub 2/!/sup +/ were determined over a range of pH 1 to 8. At 25 deg the pseudo first-order aquation rate constant for loss of the first fiuoride in 0.1 f HClO/sub 4/ is 5.3 x 10/sup -6/ sec/sup -1/, much less than the corresponding rate constants of cis-STACo(en)/sub 2/F/sub 2/!/sup +/ and cis- STACr(en)/sub 2/Cl/sub 2/!/sup +/ in 0.1 f HNO/sub 3/ . The Arrhenius activation energy is 23 plus or minus 1 kcal./mole. The aquation of cis-STACr(en)/sub 2/F/ sub 2/!/sup +/ is acid catalyzed like the cobalt analog but, unlike the dichloro cobalt and chromium analogs, presumably because the difiuoro complexes aquate by a mechanism involving an intermediate reactive protonated complex. Cation- exchange and spectral evidence indicate that the aquation product is largely, if not entirely, cisSTACr(en)/sub 2/(H/sub 2/O)F!/sup 2+/. Fluoride is taken up by one or more reaction products in later stages of the hydrolysis. The aquation appears not to be accelerated by visible light. (auth)

17 citations

Network Information
Related Topics (5)
Ligand
67.7K papers, 1.3M citations
88% related
Ruthenium
40.1K papers, 996.5K citations
88% related
Reactivity (chemistry)
43.8K papers, 833.5K citations
83% related
Intramolecular force
41.6K papers, 772.2K citations
83% related
Crystal structure
100.9K papers, 1.5M citations
82% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20232
20226
202111
202010
201914
20187