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(C4 O4)4]4-

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

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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(C4 O4)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(C4 O4)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
JournalDalton Transactions
Issue number24
DOIs
StatePublished - Dec 21 2003

ASJC Scopus subject areas

  • Inorganic Chemistry

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