Actinide diene (2-Butene-1,4-diyl) complexes. Synthesis including a methyl-induced β-hydrogen elimination reaction, structures, structural dynamics, thermochemistry, and reactivity

Gregory M. Smith, Hiroharu Suzuki, David C. Sonnenberger, Victor W. Day, Tobin J Marks

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Abstract

The synthesis and properties of the actinide s-cis-diene/cis-2-butene-1,4-diyl complexes Cp′2U(η4-C4H6) (2), Cp′2Th(η4-C4H6) (3), and Cp′2Th(η4-CH2CMeCMeCH2) (4) (Cp′ = η5-CH3)5C5) are described. They can be readily prepared from Cp′2MCl2 (M = U, Th) and the appropriate (THF)2Mg(CH2CRCRCH2) reagent. Complex 2 but not 3 can also be prepared from the methane-eliminating reaction of Cp′2U(Me)Cl and 3-butenyl Grignard. The molecular structure of 3 has been determined by single-crystal X-ray diffraction. Cp′2Th(η4-C4H6) crystallizes in the monoclinic space group P21/c - C2h5 (no. 14) with four molecules in a unit cell of dimensions a = 9.236 (3) Å, b = 14.720 (4) Å, c = 17.437 (4) Å, and β = 105.48 (2)°. Least-squares refinement led to a value for the conventional R index (on F) of 0.049 for 2450 reflections having 2θMoKᾱ <50.7° and I > 3σ(I). The molecular structure consists of an unexceptional "bent sandwich" Cp′2Th fragment coordinated to an s-cis-η 4-butadiene ligand. The average Th-C distance to the terminal carbon atoms of the butadiene ligand, 2.57 (3, 3, 3, 2) Å, is only slightly less than that to the internal carbon atoms, 2.74 (3, 1, 1, 2) Å. The actinide butadiene complexes undergo inversion of the metallacyclopentene ring which is rapid on the NMR time scale at higher temperatures; ΔG, kcal mol-1 (Tc, K) = 17.0 ± 0.3 (394, 2), 15.0 ± 0.3 (299, 3), and 10.5 ± 0.3 (208, 4). Thermochemical studies of the thorium-butadiene bond disruption enthalpy in 3 and 4 using anaerobic batch-titration (t-BuOH) calorimetry indicate that the thorium-butadiene interaction enjoys no special stabilization. D(Th-butadiene) is comparable to that for relatively "weak" thorium-to-carbon σ bonds. No evidence for s-trans-butadiene coordination is found in any of the actinide butadiene complexes. While the actinide-butadiene linkage undergoes facile hydrogenolysis and protonolysis, the activation of C-H bonds on exogenous hydrocarbon molecules is not observed. The bond disruption enthalpy data indicate that such process are thermodynamically unfavorable.

Original languageEnglish
Pages (from-to)549-561
Number of pages13
JournalOrganometallics
Volume5
Issue number3
Publication statusPublished - 1986

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Actinoid Series Elements
Thermochemistry
dynamic structural analysis
thermochemistry
Structural dynamics
butenes
dienes
butadiene
Hydrogen
elimination
reactivity
hydrogen
synthesis
Thorium
thorium
Carbon
Molecular structure
carbon
Enthalpy
molecular structure

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

Cite this

Actinide diene (2-Butene-1,4-diyl) complexes. Synthesis including a methyl-induced β-hydrogen elimination reaction, structures, structural dynamics, thermochemistry, and reactivity. / Smith, Gregory M.; Suzuki, Hiroharu; Sonnenberger, David C.; Day, Victor W.; Marks, Tobin J.

In: Organometallics, Vol. 5, No. 3, 1986, p. 549-561.

Research output: Contribution to journalArticle

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abstract = "The synthesis and properties of the actinide s-cis-diene/cis-2-butene-1,4-diyl complexes Cp′2U(η4-C4H6) (2), Cp′2Th(η4-C4H6) (3), and Cp′2Th(η4-CH2CMeCMeCH2) (4) (Cp′ = η5-CH3)5C5) are described. They can be readily prepared from Cp′2MCl2 (M = U, Th) and the appropriate (THF)2Mg(CH2CRCRCH2) reagent. Complex 2 but not 3 can also be prepared from the methane-eliminating reaction of Cp′2U(Me)Cl and 3-butenyl Grignard. The molecular structure of 3 has been determined by single-crystal X-ray diffraction. Cp′2Th(η4-C4H6) crystallizes in the monoclinic space group P21/c - C2h5 (no. 14) with four molecules in a unit cell of dimensions a = 9.236 (3) {\AA}, b = 14.720 (4) {\AA}, c = 17.437 (4) {\AA}, and β = 105.48 (2)°. Least-squares refinement led to a value for the conventional R index (on F) of 0.049 for 2450 reflections having 2θMoKᾱ <50.7° and I > 3σ(I). The molecular structure consists of an unexceptional {"}bent sandwich{"} Cp′2Th fragment coordinated to an s-cis-η 4-butadiene ligand. The average Th-C distance to the terminal carbon atoms of the butadiene ligand, 2.57 (3, 3, 3, 2) {\AA}, is only slightly less than that to the internal carbon atoms, 2.74 (3, 1, 1, 2) {\AA}. The actinide butadiene complexes undergo inversion of the metallacyclopentene ring which is rapid on the NMR time scale at higher temperatures; ΔG≠, kcal mol-1 (Tc, K) = 17.0 ± 0.3 (394, 2), 15.0 ± 0.3 (299, 3), and 10.5 ± 0.3 (208, 4). Thermochemical studies of the thorium-butadiene bond disruption enthalpy in 3 and 4 using anaerobic batch-titration (t-BuOH) calorimetry indicate that the thorium-butadiene interaction enjoys no special stabilization. D(Th-butadiene) is comparable to that for relatively {"}weak{"} thorium-to-carbon σ bonds. No evidence for s-trans-butadiene coordination is found in any of the actinide butadiene complexes. While the actinide-butadiene linkage undergoes facile hydrogenolysis and protonolysis, the activation of C-H bonds on exogenous hydrocarbon molecules is not observed. The bond disruption enthalpy data indicate that such process are thermodynamically unfavorable.",
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T1 - Actinide diene (2-Butene-1,4-diyl) complexes. Synthesis including a methyl-induced β-hydrogen elimination reaction, structures, structural dynamics, thermochemistry, and reactivity

AU - Smith, Gregory M.

AU - Suzuki, Hiroharu

AU - Sonnenberger, David C.

AU - Day, Victor W.

AU - Marks, Tobin J

PY - 1986

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N2 - The synthesis and properties of the actinide s-cis-diene/cis-2-butene-1,4-diyl complexes Cp′2U(η4-C4H6) (2), Cp′2Th(η4-C4H6) (3), and Cp′2Th(η4-CH2CMeCMeCH2) (4) (Cp′ = η5-CH3)5C5) are described. They can be readily prepared from Cp′2MCl2 (M = U, Th) and the appropriate (THF)2Mg(CH2CRCRCH2) reagent. Complex 2 but not 3 can also be prepared from the methane-eliminating reaction of Cp′2U(Me)Cl and 3-butenyl Grignard. The molecular structure of 3 has been determined by single-crystal X-ray diffraction. Cp′2Th(η4-C4H6) crystallizes in the monoclinic space group P21/c - C2h5 (no. 14) with four molecules in a unit cell of dimensions a = 9.236 (3) Å, b = 14.720 (4) Å, c = 17.437 (4) Å, and β = 105.48 (2)°. Least-squares refinement led to a value for the conventional R index (on F) of 0.049 for 2450 reflections having 2θMoKᾱ <50.7° and I > 3σ(I). The molecular structure consists of an unexceptional "bent sandwich" Cp′2Th fragment coordinated to an s-cis-η 4-butadiene ligand. The average Th-C distance to the terminal carbon atoms of the butadiene ligand, 2.57 (3, 3, 3, 2) Å, is only slightly less than that to the internal carbon atoms, 2.74 (3, 1, 1, 2) Å. The actinide butadiene complexes undergo inversion of the metallacyclopentene ring which is rapid on the NMR time scale at higher temperatures; ΔG≠, kcal mol-1 (Tc, K) = 17.0 ± 0.3 (394, 2), 15.0 ± 0.3 (299, 3), and 10.5 ± 0.3 (208, 4). Thermochemical studies of the thorium-butadiene bond disruption enthalpy in 3 and 4 using anaerobic batch-titration (t-BuOH) calorimetry indicate that the thorium-butadiene interaction enjoys no special stabilization. D(Th-butadiene) is comparable to that for relatively "weak" thorium-to-carbon σ bonds. No evidence for s-trans-butadiene coordination is found in any of the actinide butadiene complexes. While the actinide-butadiene linkage undergoes facile hydrogenolysis and protonolysis, the activation of C-H bonds on exogenous hydrocarbon molecules is not observed. The bond disruption enthalpy data indicate that such process are thermodynamically unfavorable.

AB - The synthesis and properties of the actinide s-cis-diene/cis-2-butene-1,4-diyl complexes Cp′2U(η4-C4H6) (2), Cp′2Th(η4-C4H6) (3), and Cp′2Th(η4-CH2CMeCMeCH2) (4) (Cp′ = η5-CH3)5C5) are described. They can be readily prepared from Cp′2MCl2 (M = U, Th) and the appropriate (THF)2Mg(CH2CRCRCH2) reagent. Complex 2 but not 3 can also be prepared from the methane-eliminating reaction of Cp′2U(Me)Cl and 3-butenyl Grignard. The molecular structure of 3 has been determined by single-crystal X-ray diffraction. Cp′2Th(η4-C4H6) crystallizes in the monoclinic space group P21/c - C2h5 (no. 14) with four molecules in a unit cell of dimensions a = 9.236 (3) Å, b = 14.720 (4) Å, c = 17.437 (4) Å, and β = 105.48 (2)°. Least-squares refinement led to a value for the conventional R index (on F) of 0.049 for 2450 reflections having 2θMoKᾱ <50.7° and I > 3σ(I). The molecular structure consists of an unexceptional "bent sandwich" Cp′2Th fragment coordinated to an s-cis-η 4-butadiene ligand. The average Th-C distance to the terminal carbon atoms of the butadiene ligand, 2.57 (3, 3, 3, 2) Å, is only slightly less than that to the internal carbon atoms, 2.74 (3, 1, 1, 2) Å. The actinide butadiene complexes undergo inversion of the metallacyclopentene ring which is rapid on the NMR time scale at higher temperatures; ΔG≠, kcal mol-1 (Tc, K) = 17.0 ± 0.3 (394, 2), 15.0 ± 0.3 (299, 3), and 10.5 ± 0.3 (208, 4). Thermochemical studies of the thorium-butadiene bond disruption enthalpy in 3 and 4 using anaerobic batch-titration (t-BuOH) calorimetry indicate that the thorium-butadiene interaction enjoys no special stabilization. D(Th-butadiene) is comparable to that for relatively "weak" thorium-to-carbon σ bonds. No evidence for s-trans-butadiene coordination is found in any of the actinide butadiene complexes. While the actinide-butadiene linkage undergoes facile hydrogenolysis and protonolysis, the activation of C-H bonds on exogenous hydrocarbon molecules is not observed. The bond disruption enthalpy data indicate that such process are thermodynamically unfavorable.

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