Novel molybdenum(v) squarato complexes based on the dinuclear metal–metal bonded unit: Syntheses and structural characterization of dinuclear [Mo2O4(C4O4)(R-Py)4] and tetranuclear [Mo4O8(C4O4)4]4−

Barbara Modec, Jurij V. Brenčič, Eric M. Burkholder, Jon A Zubieta

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Reactions of mononuclear oxohalomolybdates(v) with squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione) afforded two types of (Mo2O4)2+ containing species with the squarato ligand engaged in a μ2-1,2-bis(monodentate) binding mode. In the presence of pyridine (Py) or 3,5-lutidine (3,5-Lut) neutral, dinuclear complexes [Mo2O4(C4O4)(Py)4]·2MeOH·0.5Py 1a, [Mo2O4(C4O4)(Py)4]·2Py 1b and [Mo2O4(C4O4)(3,5-Lut)4]·2(3,5-Lut) 1c were obtained. A pair of nitrogen donor ligands and a squarate oxygen occupy the three coordination sites of each metal in the (Mo2O4)2+ unit in 1a, 1b and 1c. The squarate functions as a third, auxiliary bridge between a pair of molybdenum atoms at an average distance of 2.55 Å. Using 2,4,6-collidine (Col) afforded (ColMe)4[Mo4O8(C4O4)4]·2MeOH·2Col 2a (ColMe+ = N-methylcollidinium cation, NC9H14 +) and (ColH)4(PyEt)[Mo4O8(C4O4)4]Br 2b (ColH+ = protonated 2,4,6-collidine, NC8H12 +; PyEt+ = N-ethylpyridinium cation, NC7H10 +). The tetranuclear anions of 2a and 2b consist of a rare, cube-like (Mo4O43-O)4)4+ core with four squarato ligands attached to its periphery. The squarato ligands in the [Mo4O8(C4O4)4]4− anions bridge pairs of molybdenum atoms from neighbouring (Mo2O4)2+ units, spanning an average distance of 3.43 Å. The compounds were fully characterized by infrared vibrational spectroscopy, NMR spectroscopy, elemental analyses and X-ray diffraction studies.

Original languageEnglish (US)
Pages (from-to)4618-4625
Number of pages8
JournalJournal of the Chemical Society. Dalton Transactions
Volume3
Issue number24
DOIs
StatePublished - Dec 2 2003

Keywords

  • Clusters
  • Coordination chemistry
  • Molybdenum
  • Self assembly
  • Structural studies

ASJC Scopus subject areas

  • Chemistry(all)

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