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

Research output: Contribution to journalArticlepeer-review

14 Citations (SciVal)

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 Mar 2016

Bibliographical note

Funding Information:
We thank the EPSRC, the Royal Society, and the European Research Council (ERC) for their generous sponsorship of this research. We also thank Professor Robert E. Mulvey for his insightful comments and Alexander Clunie for his assistance in the CHN analysis of highly air- A nd moisture-sensitive compounds.

Keywords

  • alkali metals
  • cooperativity
  • Lewis bases
  • magnetism
  • manganese

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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