Bromo derivatives of amine and phosphine complexes of cyanodihydroborane. Synthesis and reactivity

Béla Györi, Zoltán Kovács, József Emri, István Lázár

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Bromocyanohydroborane complexes [L·BH(Br)CN], containing a chiral boron atom and dibromocyanoborane complexes (L·BBr2CN) have been synthesized from amine- and phosphine-dihydrocyanoboranes [L·BH2CN, where L=trimethylamine (Me3N), tetramethylethylenediamine (TMEDA)/2, quinuclidine (Q), picoline (Pic), tributylphosphine (Bu3P) and triphenylphosphine (Ph3P)] and bromine. Trialkylamine-bromocyanohydroboranes show fairly high hydrolytic stability, while the analogous picoline complexes hydrolyze readily. The leaving group character of bromine in amine-bromocyanohydroboranes was tested in reactions with amines. TMEDA·2BH2CN, on reaction with tetramethylethylenediamine, picoline or on heating, is transformed into a cationic complex [(TMEDA)B(H)CN+]Br- which contains a five-membered ring. This compound is also formed under mild conditions in the reaction of Pic·BH(Br)CN and TMEDA. A chiral cationic complex [Pic(Q)B(H)CN+]Br- was formed from Q·BH(Br)CN and picoline whereas reaction of Me3N·BH(Br)CN with picoline resulted in the formation of pure [Pic2B(H)CN+]Br- through substitution and transamination. Amine-dibromocyanoboranes, in contrast to amine-bromocyanohydroboranes, did not react with amines even under harsher reaction conditions. These experiments indicate that bromine can be considered as a good leaving atom in amine-bromocyanohydroboranes and these new molecules might be useful as starting materials for the synthesis of novel boron analogs of α-amino acids.

Original languageEnglish (US)
Pages (from-to)21-26
Number of pages6
JournalInorganica Chimica Acta
Volume218
Issue number1-2
DOIs
StatePublished - Apr 1994

Keywords

  • Amine complexes
  • Borane complexes
  • Boron complexes
  • Phosphine complexes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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