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Title: Chemical kinetics of nickel(III) macrocyclic complexes. Pulse radiolysis study of Ni/sup II/(CR+4H), Ni/sup II/(CR), and Ni/sup II/(CR-2H) in aqueous solutions of Br/sup -/ and CNS/sup -/. [Gamma radiation]

Abstract

Oxidation of three closely related nickel (II) macrocyclic complexes Ni/sup II/(CR-2H), Ni/sup II/(CR), and Ni/sup II/(CR+4H) via anion radical reaction has been investigated by pulse radiolysis methods. While the initial oxidation products follow the form Ni/sup III/(L)(X/sup -/)(H/sub 2/O), in agreement with previous studies (L = macrocyclic ligand; X/sup -/ = Br/sup -/, SCN/sup -/), pH- and anion-concentration-dependent behavior provides evidence indicating subsequent formation of several other complexes Ni/sup III/(L)(X/sup -/)/sub 2/, Ni/sup III/(L)(OH/sup -/)(H/sub 2/O), Ni/sup III/(L)(OH/sup -/), and Ni/sup III/(L)(OH/sup -/)/sub 2/. The kinetics for interconversion among these species have been measured and are found in several cases to exhibit reversible behavior. In those cases the associated equilibrium constants have been determined. The formation of Ni/sup III/(L)(X/sup -/)/sub 2/ may be seen to depend on the degree of macrocyclic unsaturation and character of the anion. With the exception of the fully unsaturated CR-2H ligand, Ni/sup III/(L)(OH/sup -/) and Ni/sup III/(L)(OH/sup -/)(H/sub 2/O) and Ni/sup III/(L)(OH/sup -/)/sub 2/ decay via ligand radical formation at neutral pH and higher. Steady-state radiolysis results indicate introduction of an additional double bond into the ligand. At low pH, anion-substituted Ni(III) species return almost quantitatively to their parent Ni(II) complexes.

Authors:
;
Publication Date:
Research Org.:
Univ. of Notre Dame, IN
OSTI Identifier:
5192778
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorg. Chem.; (United States); Journal Volume: 21:5
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BROMIDES; CHEMICAL REACTIONS; HETEROCYCLIC COMPOUNDS; OXIDATION; HYDROXYL RADICALS; NICKEL COMPLEXES; THIOCYANATES; WATER; RADIOLYSIS; AQUEOUS SOLUTIONS; CHEMICAL REACTION KINETICS; EXPERIMENTAL DATA; LIGANDS; PH VALUE; REACTION INTERMEDIATES; ANTITHYROID DRUGS; BROMINE COMPOUNDS; CARBONIC ACID DERIVATIVES; CHEMICAL RADIATION EFFECTS; CHEMISTRY; COMPLEXES; DATA; DECOMPOSITION; DISPERSIONS; DRUGS; HALIDES; HALOGEN COMPOUNDS; HORMONE ANTAGONISTS; HYDROGEN COMPOUNDS; INFORMATION; KINETICS; MIXTURES; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; OXYGEN COMPOUNDS; RADIATION CHEMISTRY; RADIATION EFFECTS; RADICALS; REACTION KINETICS; SOLUTIONS; TRANSITION ELEMENT COMPLEXES; 400600* - Radiation Chemistry; 400201 - Chemical & Physicochemical Properties; 400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)

Citation Formats

Morliere, P., and Patterson, L.K. Chemical kinetics of nickel(III) macrocyclic complexes. Pulse radiolysis study of Ni/sup II/(CR+4H), Ni/sup II/(CR), and Ni/sup II/(CR-2H) in aqueous solutions of Br/sup -/ and CNS/sup -/. [Gamma radiation]. United States: N. p., 1982. Web. doi:10.1021/ic00135a028.
Morliere, P., & Patterson, L.K. Chemical kinetics of nickel(III) macrocyclic complexes. Pulse radiolysis study of Ni/sup II/(CR+4H), Ni/sup II/(CR), and Ni/sup II/(CR-2H) in aqueous solutions of Br/sup -/ and CNS/sup -/. [Gamma radiation]. United States. doi:10.1021/ic00135a028.
Morliere, P., and Patterson, L.K. Sat . "Chemical kinetics of nickel(III) macrocyclic complexes. Pulse radiolysis study of Ni/sup II/(CR+4H), Ni/sup II/(CR), and Ni/sup II/(CR-2H) in aqueous solutions of Br/sup -/ and CNS/sup -/. [Gamma radiation]". United States. doi:10.1021/ic00135a028.
@article{osti_5192778,
title = {Chemical kinetics of nickel(III) macrocyclic complexes. Pulse radiolysis study of Ni/sup II/(CR+4H), Ni/sup II/(CR), and Ni/sup II/(CR-2H) in aqueous solutions of Br/sup -/ and CNS/sup -/. [Gamma radiation]},
author = {Morliere, P. and Patterson, L.K.},
abstractNote = {Oxidation of three closely related nickel (II) macrocyclic complexes Ni/sup II/(CR-2H), Ni/sup II/(CR), and Ni/sup II/(CR+4H) via anion radical reaction has been investigated by pulse radiolysis methods. While the initial oxidation products follow the form Ni/sup III/(L)(X/sup -/)(H/sub 2/O), in agreement with previous studies (L = macrocyclic ligand; X/sup -/ = Br/sup -/, SCN/sup -/), pH- and anion-concentration-dependent behavior provides evidence indicating subsequent formation of several other complexes Ni/sup III/(L)(X/sup -/)/sub 2/, Ni/sup III/(L)(OH/sup -/)(H/sub 2/O), Ni/sup III/(L)(OH/sup -/), and Ni/sup III/(L)(OH/sup -/)/sub 2/. The kinetics for interconversion among these species have been measured and are found in several cases to exhibit reversible behavior. In those cases the associated equilibrium constants have been determined. The formation of Ni/sup III/(L)(X/sup -/)/sub 2/ may be seen to depend on the degree of macrocyclic unsaturation and character of the anion. With the exception of the fully unsaturated CR-2H ligand, Ni/sup III/(L)(OH/sup -/) and Ni/sup III/(L)(OH/sup -/)(H/sub 2/O) and Ni/sup III/(L)(OH/sup -/)/sub 2/ decay via ligand radical formation at neutral pH and higher. Steady-state radiolysis results indicate introduction of an additional double bond into the ligand. At low pH, anion-substituted Ni(III) species return almost quantitatively to their parent Ni(II) complexes.},
doi = {10.1021/ic00135a028},
journal = {Inorg. Chem.; (United States)},
number = ,
volume = 21:5,
place = {United States},
year = {Sat May 01 00:00:00 EDT 1982},
month = {Sat May 01 00:00:00 EDT 1982}
}