Hydrogen bonding in tungsten (VI) salicylate free acids

Timothy E. Baroni, Scott Bembenek, Joseph A. Heppert, Rolande R. Hodel, Brian B. Laird, Martha D. Morton, Denise L. Barnes, Fusao Takusagawa

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Hydrogen-bonded free acid dimers of the formula [W(X)Cl3(Hsal-R)]2 (where X = O (1), NC6H3-2,6-Me2 (2), Ph2C2 and Hsal-R = substituted salicylate monoanion) are prepared through reactions between W(X)Cl4 precursors and functionalized salicylic acids (H2sal-R). (matrix presented) The free acids are stable at ambient temperature and exist as dimers in solution, although the structure of the dimer is not known. Spectroscopic studies show that the electronic characteristics of the π-donor ligands directly affect the electronic environments of the carb-oxylate functionality. This influence is observed in weaker binding constants of diethyl ether (KX) as the X ligand becomes more strongly π donating: O≥NC6H3-2,6-Me2>Ph2C 2. In other words, the oxo and aryl imido species are more acidic than the diphenylacetylene compounds in the Brønsted sense owing to the higher Lewis acidity of their tungsten centers. Salicylate adducts of the type W(=X)Cl3(Hsal-R)⋯OR′2 (X = O (3), NC6H3-2,6-Me2 (4)) and W(=X)Cl3(Hsal-R)⋯NEt3 (X=O (5), NC6H3-2,6-Me2 (6)) have been isolated and characterized. A comparison of two structures, W(=NC6H3-2,6-Me2)Cl 3(Hsal-3-Me⋯L) where L = OEt2 (4c) and NEt3 (6c), shows that 6c has more charge localization on both the carboxylate group and tungsten center than 4c. The charge separation in amine adducts (i.e. salts) contributes to association of these salts with the free acid (i.e. W(X)Cl3(HSal-R⋯L)⋯[W(X)Cl3(HSal-R)]). The strong hydrogen bonding exhibited by the free acids leads to the formation of supramolecular complexes organized around poly(ether) templates, including dimethoxyethane (in 3e) and 18-crown-6.

Original languageEnglish (US)
Pages (from-to)255-282
Number of pages28
JournalCoordination Chemistry Reviews
Volume174
Issue number1
StatePublished - Jul 1 1998

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salicylates
Tungsten
Salicylates
Hydrogen bonds
tungsten
Dimers
acids
Acids
hydrogen
Ether
dimers
Ethers
Salts
Ligands
adducts
Salicylic acid
salts
ligands
diethyl ether
Acidity

Keywords

  • Binding constants
  • Hydrogen bonding
  • Phenoxides
  • Salicylates
  • Supramolecular
  • Tungsten

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

Baroni, T. E., Bembenek, S., Heppert, J. A., Hodel, R. R., Laird, B. B., Morton, M. D., ... Takusagawa, F. (1998). Hydrogen bonding in tungsten (VI) salicylate free acids. Coordination Chemistry Reviews, 174(1), 255-282.

Hydrogen bonding in tungsten (VI) salicylate free acids. / Baroni, Timothy E.; Bembenek, Scott; Heppert, Joseph A.; Hodel, Rolande R.; Laird, Brian B.; Morton, Martha D.; Barnes, Denise L.; Takusagawa, Fusao.

In: Coordination Chemistry Reviews, Vol. 174, No. 1, 01.07.1998, p. 255-282.

Research output: Contribution to journalArticle

Baroni, TE, Bembenek, S, Heppert, JA, Hodel, RR, Laird, BB, Morton, MD, Barnes, DL & Takusagawa, F 1998, 'Hydrogen bonding in tungsten (VI) salicylate free acids', Coordination Chemistry Reviews, vol. 174, no. 1, pp. 255-282.
Baroni TE, Bembenek S, Heppert JA, Hodel RR, Laird BB, Morton MD et al. Hydrogen bonding in tungsten (VI) salicylate free acids. Coordination Chemistry Reviews. 1998 Jul 1;174(1):255-282.
Baroni, Timothy E. ; Bembenek, Scott ; Heppert, Joseph A. ; Hodel, Rolande R. ; Laird, Brian B. ; Morton, Martha D. ; Barnes, Denise L. ; Takusagawa, Fusao. / Hydrogen bonding in tungsten (VI) salicylate free acids. In: Coordination Chemistry Reviews. 1998 ; Vol. 174, No. 1. pp. 255-282.
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AU - Baroni, Timothy E.

AU - Bembenek, Scott

AU - Heppert, Joseph A.

AU - Hodel, Rolande R.

AU - Laird, Brian B.

AU - Morton, Martha D.

AU - Barnes, Denise L.

AU - Takusagawa, Fusao

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N2 - Hydrogen-bonded free acid dimers of the formula [W(X)Cl3(Hsal-R)]2 (where X = O (1), NC6H3-2,6-Me2 (2), Ph2C2 and Hsal-R = substituted salicylate monoanion) are prepared through reactions between W(X)Cl4 precursors and functionalized salicylic acids (H2sal-R). (matrix presented) The free acids are stable at ambient temperature and exist as dimers in solution, although the structure of the dimer is not known. Spectroscopic studies show that the electronic characteristics of the π-donor ligands directly affect the electronic environments of the carb-oxylate functionality. This influence is observed in weaker binding constants of diethyl ether (KX) as the X ligand becomes more strongly π donating: O≥NC6H3-2,6-Me2>Ph2C 2. In other words, the oxo and aryl imido species are more acidic than the diphenylacetylene compounds in the Brønsted sense owing to the higher Lewis acidity of their tungsten centers. Salicylate adducts of the type W(=X)Cl3(Hsal-R)⋯OR′2 (X = O (3), NC6H3-2,6-Me2 (4)) and W(=X)Cl3(Hsal-R)⋯NEt3 (X=O (5), NC6H3-2,6-Me2 (6)) have been isolated and characterized. A comparison of two structures, W(=NC6H3-2,6-Me2)Cl 3(Hsal-3-Me⋯L) where L = OEt2 (4c) and NEt3 (6c), shows that 6c has more charge localization on both the carboxylate group and tungsten center than 4c. The charge separation in amine adducts (i.e. salts) contributes to association of these salts with the free acid (i.e. W(X)Cl3(HSal-R⋯L)⋯[W(X)Cl3(HSal-R)]). The strong hydrogen bonding exhibited by the free acids leads to the formation of supramolecular complexes organized around poly(ether) templates, including dimethoxyethane (in 3e) and 18-crown-6.

AB - Hydrogen-bonded free acid dimers of the formula [W(X)Cl3(Hsal-R)]2 (where X = O (1), NC6H3-2,6-Me2 (2), Ph2C2 and Hsal-R = substituted salicylate monoanion) are prepared through reactions between W(X)Cl4 precursors and functionalized salicylic acids (H2sal-R). (matrix presented) The free acids are stable at ambient temperature and exist as dimers in solution, although the structure of the dimer is not known. Spectroscopic studies show that the electronic characteristics of the π-donor ligands directly affect the electronic environments of the carb-oxylate functionality. This influence is observed in weaker binding constants of diethyl ether (KX) as the X ligand becomes more strongly π donating: O≥NC6H3-2,6-Me2>Ph2C 2. In other words, the oxo and aryl imido species are more acidic than the diphenylacetylene compounds in the Brønsted sense owing to the higher Lewis acidity of their tungsten centers. Salicylate adducts of the type W(=X)Cl3(Hsal-R)⋯OR′2 (X = O (3), NC6H3-2,6-Me2 (4)) and W(=X)Cl3(Hsal-R)⋯NEt3 (X=O (5), NC6H3-2,6-Me2 (6)) have been isolated and characterized. A comparison of two structures, W(=NC6H3-2,6-Me2)Cl 3(Hsal-3-Me⋯L) where L = OEt2 (4c) and NEt3 (6c), shows that 6c has more charge localization on both the carboxylate group and tungsten center than 4c. The charge separation in amine adducts (i.e. salts) contributes to association of these salts with the free acid (i.e. W(X)Cl3(HSal-R⋯L)⋯[W(X)Cl3(HSal-R)]). The strong hydrogen bonding exhibited by the free acids leads to the formation of supramolecular complexes organized around poly(ether) templates, including dimethoxyethane (in 3e) and 18-crown-6.

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KW - Phenoxides

KW - Salicylates

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