Structural and magnetic diversity in alkali-metal Manganate chemistry: evaluating donor and alkali-metal effects in co-complexation processes

Marina Uzelac, Ivana Borilovic, Marco Amores, Thomas Cadenbach, Alan R. Kennedy, Guillem Aromí, Eva Hevia

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3 Citations (Scopus)
54 Downloads (Pure)

Abstract

By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [(KMn(CH2SiMe3)3C6H6)2] (2) and [(NaMn(CH2SiMe3)3)2(dioxane)7] (5); and to more complex supramolecular networks [(NaMn(CH2SiMe3)3)] (1) and [(Na2Mn2(CH2SiMe3)6(DABCO)2)] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [((dioxane)6K2Mn2(CH2SiMe3)4(O(CH2)2OCH=CH2)2)] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.

Original languageEnglish
Pages (from-to)4843-4854
Number of pages12
JournalChemistry - A European Journal
Volume22
Issue number14
DOIs
Publication statusPublished - 24 Feb 2016

Keywords

  • alkali metals
  • cooperativity
  • lewis bases
  • magnetism
  • Manganese

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