Pre-inverse-crowns : synthetic, structural and reactivity studies of alkali metal magnesiates primed for inverse crown formation

Martinez-Martinez, A. J. and Armstrong, D. R. and Conway, B. and Fleming, B. J. and Klett, J. and Kennedy, A. R. and Mulvey, R. E. and Robertson, S. D. and O'Hara, C. T. (2014) Pre-inverse-crowns : synthetic, structural and reactivity studies of alkali metal magnesiates primed for inverse crown formation. Chemical Science, 5 (2). pp. 771-781. ISSN 2041-6539 (https://doi.org/10.1039/C3SC52816B)

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Abstract

Two new alkali metal monoalkyl-bisamido magnesiates, the potassium compound [KMg(TMP)2nBu] and its sodium congener [NaMg(TMP) 2nBu] have been synthesised in crystalline form (TMP = 2,2,6,6-tetramethylpiperidide). Devoid of solvating ligands and possessing excellent solubility in hydrocarbon solvents, these compounds open up a new gateway for the synthesis of inverse crowns. X-ray crystallography established that [KMg(TMP)2nBu] exists in three polymorphic forms, namely a helical polymer with an infinite KNMgN chain, a hexamer with a 24-atom (KNMgN)6 ring having endo-disposed alkyl substituents, and a tetramer with a 16-atom (KNMgN)4 ring also having endo-disposed alkyl substituents. Proving their validity as pre-inverse-crowns, both magnesiates react with benzene and toluene to generate known inverse crowns in syntheses much improved from the original, supporting the idea that the metallations take place via a template effect. [KMg(TMP)2nBu] reacts with naphthalene to generate the new inverse crown [KMg(TMP)2(2-C 10H7)]6, the molecular structure of which shows a 24-atom (KNMgN)6 host ring with six naphthalene guest anions regioselectively magnesiated at the 2-position. An alternative unprecedented 1,4-dimagnesiation of naphthalene was accomplished via [NaMg(TMP) 2nBu] and its NaTMP co-complex "[NaMg(TMP) 2nBu]·NaTMP", manifested in [{Na 4Mg2(TMP)4(2,2,6-trimethyl-1,2,3,4- tetrahydropyridide)2}(1,4-C10H6)]. Adding to its novelty, this 12-atom (NaNNaNMgN)2 inverse crown structure contains two demethylated TMP ligands as well as four intact ones. Reactivity studies show that the naphthalen-ide and -di-ide inverse crowns can be regioselectively iodinated to 2-iodo and 1,4-diiodonaphthalene respectively.

ORCID iDs

Martinez-Martinez, A. J., Armstrong, D. R., Conway, B., Fleming, B. J. ORCID logoORCID: https://orcid.org/0000-0003-0111-8679, Klett, J., Kennedy, A. R. ORCID logoORCID: https://orcid.org/0000-0003-3652-6015, Mulvey, R. E. ORCID logoORCID: https://orcid.org/0000-0002-1015-2564, Robertson, S. D. ORCID logoORCID: https://orcid.org/0000-0002-9330-8770 and O'Hara, C. T.;
  • Item type:Article
    ID code:46456
    Dates:
    Date
    Event
    1 February 2014
    Published
    26 November 2013
    Published Online
    25 November 2013
    Accepted
    Subjects:Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:08 Jan 2014 16:54
    Last modified:11 Nov 2024 10:34
    URI:https://strathprints.strath.ac.uk/id/eprint/46456
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