Diruthenium carbonyl complexes bound to guaiazulene: Preparation and thermally reversible photoisomerization studies of phosphine and phosphite derivatives of (μ235-guaiazulene)Ru2 (CO)5 and iron homologues

Kouki Matsubara, Takashi Oda, Hideo Nagashima

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Abstract

Preparation of a series of (μ235-guaiazulene)M2( CO)5-n(L)n (M = Fe, Ru; n = 1, 2; L = phosphines and phosphites) was achieved by photochemical or thermal replacement of CO ligands in (μ235-guaiazulene)M2( CO)5 [M = Fe (1) or Ru (2)], which exist as mixture of two haptotropic isomers (1-A and 1-B, 2-A and 2-B), by L, and the products were subjected to thermally reversible photoisomerization studies. Phosphine and phosphite derivatives of diiron complexes (μ235-guaiazulene)Fe2 (CO)4(L) (3) and (μ235-guaiazulene)Fe2 (CO)3-(L)2 (4) were prepared in high yields by UV irradiation of 1 in the presence of L. In sharp contrast, (μ235-guaiazulene)Ru2 (CO)4(L) (5) was successfully prepared by the thermal replacement of a CO ligand in 2 by L. Although these derivatives may be formed as a mixture of two possible haptotropic isomers, only one isomer (3-A, 4-A, and 5-A) was isolated in each reaction. Detailed studies on the thermal substitution reaction of 2 revealed that formation of 5-A from a mixture of 2-A, and 2-B involved four elementary reactions: (1) the haptotropic rearrangement of 2-A to 2-B, (2) addition of L to 2-B to form (μ215-guaiazulene)Ru2 (CO)5-(L) (6), (3) η1 to η3 haptotropic shift involving dissociation of CO to form a thermodynamically less stable haptotropic isomer of 5-B, and (4) the haptotropic rearrangement of 5-B to 5-A. The intermediate 6 was isolated and completely characterized, whereas 5-B was detected by spectroscopic methods. Isolation of 6 was accomplished by reaction of 2 with L at room temperature, which furnished selective conversion of 2-B to 6 with 2-A remaining intact. This reaction actually led to kinetic separation of 2-A from a mixture of 2-A and 2-B, and complete characterization of 2-A and 2-B was made. Studies on the interconversion of haptotropic isomers of 2, 3, 4, and 5 revealed the following: (1) the diiron complexes 3 and 4 were generally inactive toward the rearrangement; (2) in contrast to facile interconversion between 2-A and 2-B, the rearrangement of diruthenium compounds, 5, was detectable only in a complex bearing a small phosphite ligand.

Original languageEnglish
Pages (from-to)881-892
Number of pages12
JournalOrganometallics
Volume20
Issue number5
DOIs
Publication statusPublished - Mar 5 2001

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phosphine
Phosphites
Photoisomerization
Carbon Monoxide
phosphines
isomers
Iron
Derivatives
iron
preparation
Isomers
ligands
Ligands
Bearings (structural)
isolation
Phosphines
guaiazulene
dissociation
substitutes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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@article{9c25c3f3ae5d46eda3286904becfc015,
title = "Diruthenium carbonyl complexes bound to guaiazulene: Preparation and thermally reversible photoisomerization studies of phosphine and phosphite derivatives of (μ2,η3:η5-guaiazulene)Ru2 (CO)5 and iron homologues",
abstract = "Preparation of a series of (μ2,η3:η5-guaiazulene)M2( CO)5-n(L)n (M = Fe, Ru; n = 1, 2; L = phosphines and phosphites) was achieved by photochemical or thermal replacement of CO ligands in (μ2,η3:η5-guaiazulene)M2( CO)5 [M = Fe (1) or Ru (2)], which exist as mixture of two haptotropic isomers (1-A and 1-B, 2-A and 2-B), by L, and the products were subjected to thermally reversible photoisomerization studies. Phosphine and phosphite derivatives of diiron complexes (μ2,η3:η5-guaiazulene)Fe2 (CO)4(L) (3) and (μ2,η3:η5-guaiazulene)Fe2 (CO)3-(L)2 (4) were prepared in high yields by UV irradiation of 1 in the presence of L. In sharp contrast, (μ2,η3:η5-guaiazulene)Ru2 (CO)4(L) (5) was successfully prepared by the thermal replacement of a CO ligand in 2 by L. Although these derivatives may be formed as a mixture of two possible haptotropic isomers, only one isomer (3-A, 4-A, and 5-A) was isolated in each reaction. Detailed studies on the thermal substitution reaction of 2 revealed that formation of 5-A from a mixture of 2-A, and 2-B involved four elementary reactions: (1) the haptotropic rearrangement of 2-A to 2-B, (2) addition of L to 2-B to form (μ2,η1:η5-guaiazulene)Ru2 (CO)5-(L) (6), (3) η1 to η3 haptotropic shift involving dissociation of CO to form a thermodynamically less stable haptotropic isomer of 5-B, and (4) the haptotropic rearrangement of 5-B to 5-A. The intermediate 6 was isolated and completely characterized, whereas 5-B was detected by spectroscopic methods. Isolation of 6 was accomplished by reaction of 2 with L at room temperature, which furnished selective conversion of 2-B to 6 with 2-A remaining intact. This reaction actually led to kinetic separation of 2-A from a mixture of 2-A and 2-B, and complete characterization of 2-A and 2-B was made. Studies on the interconversion of haptotropic isomers of 2, 3, 4, and 5 revealed the following: (1) the diiron complexes 3 and 4 were generally inactive toward the rearrangement; (2) in contrast to facile interconversion between 2-A and 2-B, the rearrangement of diruthenium compounds, 5, was detectable only in a complex bearing a small phosphite ligand.",
author = "Kouki Matsubara and Takashi Oda and Hideo Nagashima",
year = "2001",
month = "3",
day = "5",
doi = "10.1021/om000608g",
language = "English",
volume = "20",
pages = "881--892",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
number = "5",

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TY - JOUR

T1 - Diruthenium carbonyl complexes bound to guaiazulene

T2 - Preparation and thermally reversible photoisomerization studies of phosphine and phosphite derivatives of (μ2,η3:η5-guaiazulene)Ru2 (CO)5 and iron homologues

AU - Matsubara, Kouki

AU - Oda, Takashi

AU - Nagashima, Hideo

PY - 2001/3/5

Y1 - 2001/3/5

N2 - Preparation of a series of (μ2,η3:η5-guaiazulene)M2( CO)5-n(L)n (M = Fe, Ru; n = 1, 2; L = phosphines and phosphites) was achieved by photochemical or thermal replacement of CO ligands in (μ2,η3:η5-guaiazulene)M2( CO)5 [M = Fe (1) or Ru (2)], which exist as mixture of two haptotropic isomers (1-A and 1-B, 2-A and 2-B), by L, and the products were subjected to thermally reversible photoisomerization studies. Phosphine and phosphite derivatives of diiron complexes (μ2,η3:η5-guaiazulene)Fe2 (CO)4(L) (3) and (μ2,η3:η5-guaiazulene)Fe2 (CO)3-(L)2 (4) were prepared in high yields by UV irradiation of 1 in the presence of L. In sharp contrast, (μ2,η3:η5-guaiazulene)Ru2 (CO)4(L) (5) was successfully prepared by the thermal replacement of a CO ligand in 2 by L. Although these derivatives may be formed as a mixture of two possible haptotropic isomers, only one isomer (3-A, 4-A, and 5-A) was isolated in each reaction. Detailed studies on the thermal substitution reaction of 2 revealed that formation of 5-A from a mixture of 2-A, and 2-B involved four elementary reactions: (1) the haptotropic rearrangement of 2-A to 2-B, (2) addition of L to 2-B to form (μ2,η1:η5-guaiazulene)Ru2 (CO)5-(L) (6), (3) η1 to η3 haptotropic shift involving dissociation of CO to form a thermodynamically less stable haptotropic isomer of 5-B, and (4) the haptotropic rearrangement of 5-B to 5-A. The intermediate 6 was isolated and completely characterized, whereas 5-B was detected by spectroscopic methods. Isolation of 6 was accomplished by reaction of 2 with L at room temperature, which furnished selective conversion of 2-B to 6 with 2-A remaining intact. This reaction actually led to kinetic separation of 2-A from a mixture of 2-A and 2-B, and complete characterization of 2-A and 2-B was made. Studies on the interconversion of haptotropic isomers of 2, 3, 4, and 5 revealed the following: (1) the diiron complexes 3 and 4 were generally inactive toward the rearrangement; (2) in contrast to facile interconversion between 2-A and 2-B, the rearrangement of diruthenium compounds, 5, was detectable only in a complex bearing a small phosphite ligand.

AB - Preparation of a series of (μ2,η3:η5-guaiazulene)M2( CO)5-n(L)n (M = Fe, Ru; n = 1, 2; L = phosphines and phosphites) was achieved by photochemical or thermal replacement of CO ligands in (μ2,η3:η5-guaiazulene)M2( CO)5 [M = Fe (1) or Ru (2)], which exist as mixture of two haptotropic isomers (1-A and 1-B, 2-A and 2-B), by L, and the products were subjected to thermally reversible photoisomerization studies. Phosphine and phosphite derivatives of diiron complexes (μ2,η3:η5-guaiazulene)Fe2 (CO)4(L) (3) and (μ2,η3:η5-guaiazulene)Fe2 (CO)3-(L)2 (4) were prepared in high yields by UV irradiation of 1 in the presence of L. In sharp contrast, (μ2,η3:η5-guaiazulene)Ru2 (CO)4(L) (5) was successfully prepared by the thermal replacement of a CO ligand in 2 by L. Although these derivatives may be formed as a mixture of two possible haptotropic isomers, only one isomer (3-A, 4-A, and 5-A) was isolated in each reaction. Detailed studies on the thermal substitution reaction of 2 revealed that formation of 5-A from a mixture of 2-A, and 2-B involved four elementary reactions: (1) the haptotropic rearrangement of 2-A to 2-B, (2) addition of L to 2-B to form (μ2,η1:η5-guaiazulene)Ru2 (CO)5-(L) (6), (3) η1 to η3 haptotropic shift involving dissociation of CO to form a thermodynamically less stable haptotropic isomer of 5-B, and (4) the haptotropic rearrangement of 5-B to 5-A. The intermediate 6 was isolated and completely characterized, whereas 5-B was detected by spectroscopic methods. Isolation of 6 was accomplished by reaction of 2 with L at room temperature, which furnished selective conversion of 2-B to 6 with 2-A remaining intact. This reaction actually led to kinetic separation of 2-A from a mixture of 2-A and 2-B, and complete characterization of 2-A and 2-B was made. Studies on the interconversion of haptotropic isomers of 2, 3, 4, and 5 revealed the following: (1) the diiron complexes 3 and 4 were generally inactive toward the rearrangement; (2) in contrast to facile interconversion between 2-A and 2-B, the rearrangement of diruthenium compounds, 5, was detectable only in a complex bearing a small phosphite ligand.

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