Kinetic and mechanistic study of the linkage isomerization of substituted (5-phenyltetrazolato)pentaamminecobalt(III) complexes

John H. Hall, William L. Purcell

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The facile synthesis of a series of (5-(R-phenyl)tetrazolato)pentaamminecobalt(III) complexes which undergo a spontaneous linkage isomerization reaction from the N1- to the N2-bonded linkage isomers is reported for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2. The first-order rate processes show a strong pH dependence with rate constants for the protonated species (k3+) approximately 50 times those of the corresponding deprotonated complexes (k2+). The rate constants and the acid equilibrium constants (Ka1) for the N1 complexes show a good correlation with the Hammett σ parameter, while the N2 acid equilibrium constants (Ka2, determined separately) correlate well with the σ- parameter. Kinetic and thermodynamic parameters (k3+, k2+, Ka1, and Ka2) determined for each system at 25°C and I = 1.0 M are 3.6 × 10-3, 4.85 × 10-5, 0.14, and 0.13; 4.8 × 10-3, 6.1 × 10-5, 0.26, and 0.16; 9.4 × 10-3, 1.40 × 10-4, 0.40, and 0.27; 2.1 × 10-2, 2.3 × 10-4, 1.1, and 0.62; and 3.1 × 10-2, 5.6 × 10-4, 1.8, and 2.2 for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2, respectively, where units of s-1 for the rate constants and M for the acid dissociation constants are quoted. Relief of steric hindrance as a major driving force for the isomerization is consistent with the data presented. An empirical method for the determination of % N2-bonded species present in N1 preparations is presented.

Original languageEnglish
Pages (from-to)3806-3811
Number of pages6
JournalInorganic Chemistry
Volume29
Issue number19
StatePublished - Dec 1 1990

Fingerprint

Isomerization
linkages
isomerization
Rate constants
Equilibrium constants
Kinetics
Acids
kinetics
Isomers
acids
Thermodynamics
isomers
dissociation
thermodynamics
preparation
synthesis

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Kinetic and mechanistic study of the linkage isomerization of substituted (5-phenyltetrazolato)pentaamminecobalt(III) complexes. / Hall, John H.; Purcell, William L.

In: Inorganic Chemistry, Vol. 29, No. 19, 01.12.1990, p. 3806-3811.

Research output: Contribution to journalArticle

@article{77e63469b7e34e428168c8fdf9c432f9,
title = "Kinetic and mechanistic study of the linkage isomerization of substituted (5-phenyltetrazolato)pentaamminecobalt(III) complexes",
abstract = "The facile synthesis of a series of (5-(R-phenyl)tetrazolato)pentaamminecobalt(III) complexes which undergo a spontaneous linkage isomerization reaction from the N1- to the N2-bonded linkage isomers is reported for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2. The first-order rate processes show a strong pH dependence with rate constants for the protonated species (k3+) approximately 50 times those of the corresponding deprotonated complexes (k2+). The rate constants and the acid equilibrium constants (Ka1) for the N1 complexes show a good correlation with the Hammett σ parameter, while the N2 acid equilibrium constants (Ka2, determined separately) correlate well with the σ- parameter. Kinetic and thermodynamic parameters (k3+, k2+, Ka1, and Ka2) determined for each system at 25°C and I = 1.0 M are 3.6 × 10-3, 4.85 × 10-5, 0.14, and 0.13; 4.8 × 10-3, 6.1 × 10-5, 0.26, and 0.16; 9.4 × 10-3, 1.40 × 10-4, 0.40, and 0.27; 2.1 × 10-2, 2.3 × 10-4, 1.1, and 0.62; and 3.1 × 10-2, 5.6 × 10-4, 1.8, and 2.2 for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2, respectively, where units of s-1 for the rate constants and M for the acid dissociation constants are quoted. Relief of steric hindrance as a major driving force for the isomerization is consistent with the data presented. An empirical method for the determination of {\%} N2-bonded species present in N1 preparations is presented.",
author = "Hall, {John H.} and Purcell, {William L.}",
year = "1990",
month = "12",
day = "1",
language = "English",
volume = "29",
pages = "3806--3811",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "19",

}

TY - JOUR

T1 - Kinetic and mechanistic study of the linkage isomerization of substituted (5-phenyltetrazolato)pentaamminecobalt(III) complexes

AU - Hall, John H.

AU - Purcell, William L.

PY - 1990/12/1

Y1 - 1990/12/1

N2 - The facile synthesis of a series of (5-(R-phenyl)tetrazolato)pentaamminecobalt(III) complexes which undergo a spontaneous linkage isomerization reaction from the N1- to the N2-bonded linkage isomers is reported for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2. The first-order rate processes show a strong pH dependence with rate constants for the protonated species (k3+) approximately 50 times those of the corresponding deprotonated complexes (k2+). The rate constants and the acid equilibrium constants (Ka1) for the N1 complexes show a good correlation with the Hammett σ parameter, while the N2 acid equilibrium constants (Ka2, determined separately) correlate well with the σ- parameter. Kinetic and thermodynamic parameters (k3+, k2+, Ka1, and Ka2) determined for each system at 25°C and I = 1.0 M are 3.6 × 10-3, 4.85 × 10-5, 0.14, and 0.13; 4.8 × 10-3, 6.1 × 10-5, 0.26, and 0.16; 9.4 × 10-3, 1.40 × 10-4, 0.40, and 0.27; 2.1 × 10-2, 2.3 × 10-4, 1.1, and 0.62; and 3.1 × 10-2, 5.6 × 10-4, 1.8, and 2.2 for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2, respectively, where units of s-1 for the rate constants and M for the acid dissociation constants are quoted. Relief of steric hindrance as a major driving force for the isomerization is consistent with the data presented. An empirical method for the determination of % N2-bonded species present in N1 preparations is presented.

AB - The facile synthesis of a series of (5-(R-phenyl)tetrazolato)pentaamminecobalt(III) complexes which undergo a spontaneous linkage isomerization reaction from the N1- to the N2-bonded linkage isomers is reported for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2. The first-order rate processes show a strong pH dependence with rate constants for the protonated species (k3+) approximately 50 times those of the corresponding deprotonated complexes (k2+). The rate constants and the acid equilibrium constants (Ka1) for the N1 complexes show a good correlation with the Hammett σ parameter, while the N2 acid equilibrium constants (Ka2, determined separately) correlate well with the σ- parameter. Kinetic and thermodynamic parameters (k3+, k2+, Ka1, and Ka2) determined for each system at 25°C and I = 1.0 M are 3.6 × 10-3, 4.85 × 10-5, 0.14, and 0.13; 4.8 × 10-3, 6.1 × 10-5, 0.26, and 0.16; 9.4 × 10-3, 1.40 × 10-4, 0.40, and 0.27; 2.1 × 10-2, 2.3 × 10-4, 1.1, and 0.62; and 3.1 × 10-2, 5.6 × 10-4, 1.8, and 2.2 for R = 4-CH3, H, 4-Cl, 3-CF3, and 4-NO2, respectively, where units of s-1 for the rate constants and M for the acid dissociation constants are quoted. Relief of steric hindrance as a major driving force for the isomerization is consistent with the data presented. An empirical method for the determination of % N2-bonded species present in N1 preparations is presented.

UR - http://www.scopus.com/inward/record.url?scp=0001481788&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001481788&partnerID=8YFLogxK

M3 - Article

VL - 29

SP - 3806

EP - 3811

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 19

ER -