Synthesis of open-shell, bimetallic Mn/Fe trinuclear clusters

Tamara M. Powers, Nina X. Gu, Alison R. Fout, Anne M. Baldwin, Raúl Hernández Sánchez, Denise M. Alfonso, Yu Sheng Chen, Shao Liang Zheng, Theodore A. Betley

Research output: Contribution to journalArticlepeer-review

Abstract

Concomitant deprotonation and metalation of hexadentate ligand platform tbsLH6 (tbsLH6 = 1,3,5-C 6H9(NHC6H4-o-NHSiMe2 tBu)3) with divalent transition metal starting materials Fe2(Mes)4 (Mes = mesityl) or Mn3(Mes) 6 in the presence of tetrahydrofuran (THF) resulted in isolation of homotrinuclear complexes (tbsL)Fe3(THF) and ( tbsL)Mn3(THF), respectively. In the absence of coordinating solvent (THF), the deprotonation and metalation exclusively afforded dinuclear complexes of the type (tbsLH2)M 2 (M = Fe or Mn). The resulting dinuclear species were utilized as synthons to prepare bimetallic trinuclear clusters. Treatment of ( tbsLH2)Fe2 complex with divalent Mn source (Mn2(N(SiMe3)2)4) afforded the bimetallic complex (tbsL)Fe2Mn(THF), which established the ability of hexamine ligand tbsLH6 to support mixed metal clusters. The substitutional homogeneity of (tbsL)Fe 2Mn(THF) was determined by 1H NMR, 57Fe Mössbauer, and X-ray fluorescence. Anomalous scattering measurements were critical for the unambiguous assignment of the trinuclear core composition. Heating a solution of (tbsLH2)Mn2 with a stoichiometric amount of Fe2(Mes)4 (0.5 mol equiv) affords a mixture of both (tbsL)Mn2Fe(THF) and ( tbsL)Fe2Mn(THF) as a result of the thermodynamic preference for heavier metal substitution within the hexa-anilido ligand framework. These results demonstrate for the first time the assembly of mixed metal cluster synthesis in an unbiased ligand platform.

Original languageEnglish (US)
Pages (from-to)14448-14458
Number of pages11
JournalJournal of the American Chemical Society
Volume135
Issue number38
DOIs
StatePublished - Sep 25 2013

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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