Nuclear magnetic resonance studies of ligand-exchange processes. II. Kinetics of configurational rearrangement for some mixed β-diketonate complexes of gallium(III)

Thomas J. PinnaVaia; John M. Sebeson; David A. Case

doi:10.1021/ic50073a046

Nuclear magnetic resonance studies of ligand-exchange processes. II. Kinetics of configurational rearrangement for some mixed β-diketonate complexes of gallium(III)

Thomas J. PinnaVaia, John M. Sebeson, David A. Case

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Abstract

Nmr studies of Ga(acac)₂(hfac) in dichloromethane and of Ga(acac)₂(bzbz) in benzene, where acac = acetylacetonate, hfac = hexafluoroacetylacetonate, and bzbz = dibenzoylmethanate, have shown that the molecules undergo intramolecular configurational rearrangement processes which result in exchange of nonequivalent terminal methyl groups on the acac ligands. First-order rate constants for the rearrangement processes have been determined by line-broadening techniques. The rate of methyl group exchange at 25° for Ga(acac)₂(hfac) is ca. 10⁴ times larger than the rate for Ga(acac)₂(bzbz). Activation energies and activation entropies were found to be, respectively: 14.5 ± 1.1 kcal/mol and 1.7 ± 4.4 eu for Ga(acac)₂(hfac); 20.6 ± 2.7 kcal/mol and 3.5 ± 8.0 eu for Ga(acac)₂(bzbz). The activation energies are discussed briefly and are compared with available parameters for terminal group exchange in other group IIIb metal γ-diketonates.

Original language	English (US)
Pages (from-to)	644-648
Number of pages	5
Journal	Inorganic Chemistry
Volume	8
Issue number	3
DOIs	https://doi.org/10.1021/ic50073a046
State	Published - Mar 1 1969
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physical and Theoretical Chemistry
Inorganic Chemistry

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title = "Nuclear magnetic resonance studies of ligand-exchange processes. II. Kinetics of configurational rearrangement for some mixed β-diketonate complexes of gallium(III)",

abstract = "Nmr studies of Ga(acac)2(hfac) in dichloromethane and of Ga(acac)2(bzbz) in benzene, where acac = acetylacetonate, hfac = hexafluoroacetylacetonate, and bzbz = dibenzoylmethanate, have shown that the molecules undergo intramolecular configurational rearrangement processes which result in exchange of nonequivalent terminal methyl groups on the acac ligands. First-order rate constants for the rearrangement processes have been determined by line-broadening techniques. The rate of methyl group exchange at 25° for Ga(acac)2(hfac) is ca. 104 times larger than the rate for Ga(acac)2(bzbz). Activation energies and activation entropies were found to be, respectively: 14.5 ± 1.1 kcal/mol and 1.7 ± 4.4 eu for Ga(acac)2(hfac); 20.6 ± 2.7 kcal/mol and 3.5 ± 8.0 eu for Ga(acac)2(bzbz). The activation energies are discussed briefly and are compared with available parameters for terminal group exchange in other group IIIb metal γ-diketonates.",

author = "PinnaVaia, {Thomas J.} and Sebeson, {John M.} and Case, {David A.}",

year = "1969",

month = mar,

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doi = "10.1021/ic50073a046",

language = "English (US)",

volume = "8",

pages = "644--648",

journal = "Inorganic Chemistry",

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T1 - Nuclear magnetic resonance studies of ligand-exchange processes. II. Kinetics of configurational rearrangement for some mixed β-diketonate complexes of gallium(III)

AU - PinnaVaia, Thomas J.

AU - Sebeson, John M.

AU - Case, David A.

PY - 1969/3/1

Y1 - 1969/3/1

N2 - Nmr studies of Ga(acac)2(hfac) in dichloromethane and of Ga(acac)2(bzbz) in benzene, where acac = acetylacetonate, hfac = hexafluoroacetylacetonate, and bzbz = dibenzoylmethanate, have shown that the molecules undergo intramolecular configurational rearrangement processes which result in exchange of nonequivalent terminal methyl groups on the acac ligands. First-order rate constants for the rearrangement processes have been determined by line-broadening techniques. The rate of methyl group exchange at 25° for Ga(acac)2(hfac) is ca. 104 times larger than the rate for Ga(acac)2(bzbz). Activation energies and activation entropies were found to be, respectively: 14.5 ± 1.1 kcal/mol and 1.7 ± 4.4 eu for Ga(acac)2(hfac); 20.6 ± 2.7 kcal/mol and 3.5 ± 8.0 eu for Ga(acac)2(bzbz). The activation energies are discussed briefly and are compared with available parameters for terminal group exchange in other group IIIb metal γ-diketonates.

AB - Nmr studies of Ga(acac)2(hfac) in dichloromethane and of Ga(acac)2(bzbz) in benzene, where acac = acetylacetonate, hfac = hexafluoroacetylacetonate, and bzbz = dibenzoylmethanate, have shown that the molecules undergo intramolecular configurational rearrangement processes which result in exchange of nonequivalent terminal methyl groups on the acac ligands. First-order rate constants for the rearrangement processes have been determined by line-broadening techniques. The rate of methyl group exchange at 25° for Ga(acac)2(hfac) is ca. 104 times larger than the rate for Ga(acac)2(bzbz). Activation energies and activation entropies were found to be, respectively: 14.5 ± 1.1 kcal/mol and 1.7 ± 4.4 eu for Ga(acac)2(hfac); 20.6 ± 2.7 kcal/mol and 3.5 ± 8.0 eu for Ga(acac)2(bzbz). The activation energies are discussed briefly and are compared with available parameters for terminal group exchange in other group IIIb metal γ-diketonates.

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Nuclear magnetic resonance studies of ligand-exchange processes. II. Kinetics of configurational rearrangement for some mixed β-diketonate complexes of gallium(III)

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