- Mixed triorganobismuthines RAr2Bi [Ar = C6F5, 2,4,6-(C6F5)3C6H2] and hypervalent racemic Bi-chiral diorganobismuth(III) bromides RArBiBr (Ar = C6F5, Mes, Ph) with the ligand R = 2-(Me2NCH2)C6H4. Influences of the organic substituent
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Triorganobismuthines R(C6F5)2Bi (1) and R[2,4,6-(C6F5)3C6H2]2Bi (2) [R = 2-(Me2NCH2)C6H4] were synthesized by reaction of RBiBr2 with C6F5MgBr and 2,4,6-(C6F5)3C6H2Li, respectively, in a 1:2 molar ratio. The Bi-chiral bromides R(C6F5)BiBr (3), R(Mes)BiBr (4), and R(Ph)BiBr (5) were obtained from RBiBr2 and C6F5MgBr, MesMgBr or PhMgBr, or from PhBiBr2 and RLi, in a 1:1 molar ratio. The molecular structures of 1-5 were determined by single-crystal X-ray diffraction and are discussed taking into account the chirality of the species. Supramolecular aspects in the solid state are presented. The solution behaviour of the title compounds, including dynamic aspects, are discussed on the basis of multinuclear (1H, 13C, 19F) NMR spectroscopy.
- Olaru, Marian,Nema, Mihai G.,Soran, Albert,Breunig, Hans J.,Silvestru, Cristian
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p. 9419 - 9428
(2016/07/06)
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- Chiral Chlorobismutines Stabilized by the Intramolecular Coordination of an N,N-Dimethylamino Group: X-Ray Structure Analysis, Asymmetric Induction at the Bismuth Centre and Dynamic behaviour in Solution
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Chiral chlorobismuthines 3 stabilized by intramolecular coordination of an N,N-dimethylamino group have been synthesized by the selective fluorodearylation of the bismuthines 1 with boron trifluoride-diethyl ether, followed by halogen exchange of the resulting fluorobismuthines 2 with brine.An X-ray crystallographic structure analysis of 3b revealed that the bismuth centre has a distorted pseudotrigonal bipyramidal structure through the formation of a hypervalent 3-centre 4-electron bond with the chlorine and nitrogen atoms at apical positions. 1H NMR spectra of compounds 3 in CDCl3 at room temperature reflected their fixed conformation in the solid state.Chiral chlorobismuthines 7a and 7b were obtained in a similar manner starting from optically pure (R)-N,N-dimethyl-1-phenylethylamine as mixture of two diastereomers (77:23 and 78:22, respectively), the isomeric ratios of which were not influenced by the equatorial aryl group present.Variable-temperature dynamic 1H NMR spectra of the diastereomeric mixture of 7a provided important information about its behaviour in solution; in toluene dynamic but reversible dissociation of intramolecular Bi-N coordination was observed only at elevated temperatures, while in -DMSO it occured quite easily below room temperature, leading to the inversion of configuration at the chiral bismuth centre.
- Suzuki, Hitomi,Murafuji, Toshihiro,Matano, Yoshihiro,Azuma, Nagao
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p. 2969 - 2974
(2007/10/02)
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