Structures and Magnetic Properties of Dimeric Copper(II) Benzoylformates

Akihiko Harada, Masanobu Tsuchimoto, Shigeru Ohba, Kaku Iwasawa, Tadashi Tokii

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Structures of six dimeric copper(II) benzoylformates (I)-(VI) have been determined by single crystal X-ray diffraction and the magnitudes of the spin-exchange interaction (H = -2751S2) have been determined based on the magnetic susceptibility measurement. (I): Tetrakis(μ-benzoylformato-O,O′)bis(pyridine)dicopper(II), [Cu(C8H5O3)2C5H 5N]2, -2J = 648cm-1. (II): Tetrakis-(μ-benzoylformato-O,O′)bis(2-methylpyridine)dicopper(II), [Cu(C8H5O3)2C6H 7N]2, -2J = 656cm-1. (III): Tetrakis(M-benzoylformato-0,<7)bis(3-methylpyridine)-dicopper(II) monobenzene solvate, [Cu(C8H5O3)2-C6H 7N]2.C6H6, -2J = 649cm-1. (IV): Tetrakis(μ-benzoylformato-O,O′)bis(4-methylpyridine)dicopper(II), [Cu-(C8H5O3)2C6H 7N]2, -27 = 625cm-1. (V): Bis(2,3-dimethylpyridinium) tetrakis(μ-benzoylformato-O,O′)-bis(chloride)dicopper(II) dibenzene solvate, 2C7H10N.-[Cu(C8H5O3) 2Cl]2.2C6H6, -27 = 618cm-1. (VI): Tetrakis(benzoylformato-O,O′)bis(caffeine)dicopper(II) dibenzene solvate, [Cu(C8H5O3)2C8H 10N4O2]2.2C6H 6, -2J = 651cm-1 (caffeine = 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione). In the binuclear cage structure the coordination geometry around the CuII atoms is typical square pyramidal with Cu⋯Cu distances 2.725 (1)-2.843 (1) Å. An ab initio molecular orbital calculation for the benzoylformate ion indicates that the unusually strong antiferromagnetic interaction in dimeric copper(II) benzoylformates is attributed to the electronic effect of the α-keto group in the bridging carboxylate moiety. This is in accordance with a positive linear relationship between -2J of the copper(II) carboxylates and the diagonal part of the 2px orbital population of the carboxylate C atom in the symmetrical HOMO, highest occupied molecular orbital (x is parallel to the C - R bond axis in the RCOO- ion).

Original languageEnglish
Pages (from-to)654-661
Number of pages8
JournalActa Crystallographica Section B: Structural Science
Volume53
Issue number4
DOIs
Publication statusPublished - 1997 Aug 1

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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