title: Tridentate Lewis Acids Based on 1,3,5-Trisilacyclohexane Backbones and an Example of Their Host-Guest Chemistry.
abstract: Directed tridentate Lewis acids based on the 1,3,5-trisilacyclohexane skeleton with three ethynyl groups [CH2Si(Me)(C2H)]3 were synthesised and functionalised by hydroboration with HB(C6F5)2, yielding the ethenylborane {CH2Si(Me)[C2H2B(C6F5)2]}3, and by metalation with gallium and indium organyls affording {CH2Si(Me)[C2M(R)2]}3 (M = Ga, In, R = Me, Et). In the synthesis of the backbone the influence of substituents (MeO, EtO and iPrO groups at Si) on the orientation of the methyl group was studied with the aim to increase the abundance of the all-cis isomer. New compounds were identified by elemental analyses, multi-nuclear NMR spectroscopy and in some cases by IR spectroscopy. Crystal structures were obtained for cis-trans-[CH2Si(Me)(Cl)]3, all-cis-[CH2Si(Me)(H)]3, all-cis-[CH2Si(Me)(C2H)]3, cis-trans-[CH2Si(Me)(C2H)]3 and all-cis-[CH2Si(Me)(C2SiMe3)]3. A gas-phase electron diffraction experiment for all-cis-[CH2Si(Me)(C2H)]3 provides information on the relative stabilities of the all-equatorial and all-axial form; the first is preferred in both solid and gas phase. The gallium-based Lewis acid {CH2Si(Me)[C2Ga(Et)2]}3 was reacted with a tridentate Lewis base (1,3,5-trimethyl-1,3,5-triazacyclohexane) in an NMR titration experiment. The generated host-guest complexes involved in the equilibria during this reaction were identified by DOSY NMR spectroscopy by comparing measured diffusion coefficients with those of the suitable reference compounds of same size and shape.
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Eugen
authors.initials: E
authors.lastname: Weisheim
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Reuter
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Peter
authors.initials: P
authors.lastname: Heinrichs
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Yury V
authors.initials: YV
authors.lastname: Vishnevskiy
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Andreas
authors.initials: A
authors.lastname: Mix
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Beate
authors.initials: B
authors.lastname: Neumann
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Stammler
authors.affiliation: Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien CM2, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld (Germany), Fax: (+49) 521-106-6026. mitzel@uni-bielefeld.de.
authors.forename: Norbert W
authors.initials: NW
authors.lastname: Mitzel
keywords: Lewis acids; NMR spectroscopy; hydroboration; metalation; trisilacyclohexane