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A structural and computational study of synthetically important alkali-metal/tetramethylpiperidide (tmp) amine solvates

Armstrong, D.R. and Graham, D.V. and Kennedy, A.R. and Mulvey, R.E. and O'Hara, C.T. (2008) A structural and computational study of synthetically important alkali-metal/tetramethylpiperidide (tmp) amine solvates. Chemistry - A European Journal, 14 (26). pp. 8025-8034. ISSN 0947-6539

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Abstract

Two heavy alkali-metal salts of the sterically demanding amine, 2,2,6,6-tetramethylpiperidine (TMPH), have been prepared using different methodologies. Complex 1, [{(tmeda)Na(tmp)}2] (TMEDA=N,N, N,N-tetramethylethylenediamine), can be synthesized by a deprotonative route. This is achieved by reacting butylsodium with TMPH in the presence of excess TMEDA in hexane. The potassium congener [{(tmeda)K(tmp)}2] (2), can be prepared by treating KTMP (made using a metathesis reaction between LiTMP and potassium tert-butoxide) with an excess of TMEDA in hexane. In the solid state, 1 and 2 are essentially isostructural. They are discretely dimeric and their framework consists of a four-membered M-N-M-N ring (M=Na or K, N=TMP). Due to the high steric demand of the TMP ligand, the TMEDA molecules bind to the metal centers in an asymmetric manner. In 2, each of the coordination spheres of the metals is completed by an agostic KCH3(TMP) interaction. DFT calculations at the B3 LYP/6-311G** level give an insight into why 1 and 2 adopt dramatically different structures from their previously reported, open-dimeric, lithium counterpart. The theoretical work also focuses on the TMEDA-free parent amide complexes and reveals that the energy difference for the formation of [{M(tmp)}x] (in which, M=Li or Na, x=3 or 4; and M=K, x=2, 3 or 4) are small. (Abstract copied from: http://www3.interscience.wiley.com/journal/120840676/abstract)

Item type: Article
ID code: 17036
Notes: http://suprimo.lib.strath.ac.uk/primo_library/libweb/action/display.do?ct=display&doc=SUSFX954925573930&indx=2&vl(freeText0)=Chemistry-a%20european%20journal&fn=search&fctV=5672704&tab=local&fctN=facet_frbrgroupid&scp.scps=scope%3A(SU)&mode=Basic&dscnt=0&ct=search&cs=frb&vl(54032236UI0)=lsr02&vl(96071691UI1)=all_items&dstmp=1271678961614&frbg=5672704&srt=rank&indx=1&dum=true&vid=SUVU01
Keywords: alkali metals, amides, coordination chemistry, density functional calculations, structure elucidation, Chemistry, Physical and theoretical chemistry, Chemistry(all)
Subjects: Science > Chemistry
Science > Chemistry > Physical and theoretical chemistry
Department: Faculty of Science > Pure and Applied Chemistry
Related URLs:
    Depositing user: Strathprints Administrator
    Date Deposited: 19 Apr 2010 13:17
    Last modified: 28 Mar 2014 05:15
    URI: http://strathprints.strath.ac.uk/id/eprint/17036

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