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Synthesis 2018; 50(18): 3679-3685
DOI: 10.1055/s-0037-1610180
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© Georg Thieme Verlag Stuttgart · New York

Synthesis and Electrochemical Study of 1,1′-Thienyl-Substituted Fused Bis-germatranes with a Core 5c-6e Hyperbond

Vitalijs Romanovs*
a   Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, Latvia   Email: vitalijs.romanovs@inbox.lv
,
Jana Spura
a   Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, Latvia   Email: vitalijs.romanovs@inbox.lv
,
Viatcheslav Jouikov  *
b   UMR 6226 ISCR, CORINT, University of Rennes I, 35042, Rennes, France   Email: vjouikov@univ-rennes1.fr
› Author AffiliationsThe authors are grateful for the financial support of this project by EC 7th Framework Program REGPOT-CT-2013-316149-InnovaBalt and by OSMOSE No 39660QC.
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Publication History

Received: 27 March 2018

Accepted after revision: 15 May 2018

Publication Date:
14 June 2018 (online)

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Published as part of the Special Section on the Main Group Metal Chemistry Symposium

Abstract

Novel fused bis-germatranes containing three hypercoordinated atoms (two Ge and one N) and substituted at the 1,1′-positions with bromo-thienyl groups [(3-bromo-2-thienyl)-, (3,5-dibromo-2-thienyl)-, and 3-(4-bromo)-2-thienyl] have been synthesized from the corresponding triethoxy(thienyl)germanes and tris(1,3-dihydroxypropan-2-yl)amine. The doubly degenerated HOMO and HOMO-1 in these compounds are localized on the thienyl substituents while a 5c-6e hyperbond of the bis-germatranyl core (C–Ge←N→Ge–C system) is only a lower lying HOMO-2. Square-wave pulse voltammetry in CH3CN/0.1 M Bu4NPF6 shows all three compounds to undergo reversible electrochemical oxidation affecting one thienyl substituent. The DFT B3LYP/Lanl2DZ//HF/6-311G(d,p) calculations of their cation radicals suggest the enhancement and shortening of the N→Ge intramolecular dative bond on the side of the oxidized thienyl unit because of the positive charge and the increased acceptor character of the latter; this is accompanied by the loss of the N→Ge dative bond on the side of the non-oxidized substituent and a substantial pyramidalization of the Ge atom.

Key words

bis-germatranes - cation radicals - hyperbonds - electrochemical oxidation

Supporting Information

    Supporting information for this article is available online at https://doi.org/10.1055/s-0037-1610180. 1H and 13C NMR spectra of the new bis-germatranes are included.
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