Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The synthesis of nitrogen and boron substituted derivatives of the 1-amino-closo-dodecaborate anion(1-) 1 is reported. Reasonable yields of the [R₂NH-B₁₂H₁₁]^- derivatives (R = C₆H₅CH₂, 2-C₁₀H₇CH₂, n-C₁₆H₃₃, n-C₁₂H₂₅) were obtained via conventional alkylation of 1 in aqueous propan-2-ol, starting from bulky primary alkylhalides. These [R₂NH-B₁₂H₁₁]^- derivatives were subsequently methylated by dimethyl sulfate under similar conditions. Reaction of 1 with palmitoyl chloride gave under anhydrous conditions the corresponding N-acyl derivative. Reaction of 1 with hydroxymethyl-18-crown-6 tosylate in THF in the presence of NaH led to the novel [(18-crown-6-CH₂)₂NH-B₁₂H₁₁]^- anion, the Cs⁺ salt of which exhibits unusual solubility properties. A direct cyclization reaction of pentaethylene glycol ditosylate with 1 gave under similar conditions [(15-azacrown)-5-B₁₂H₁₁]^-, the first known closo-borate anion with an attached aza-crown ring. These species exhibit potentially interesting complexation efficiency and solubility properties. Selective substitution of the boron cage by a bulky naphthyl substituent was achieved by palladium-mediated cross-coupling reaction between 1 and 1-BrMgC₁₀H₇. All derivatives were characterized by high-field ¹¹B, ¹H NMR and negative FAB mass spectrometry methods.

Keywords: Boranes; closo-Hydroborate anions; Dodecahydro-closo-dodecaborate(2-) anion; 1-Amino-undecahydro-closo-dodecaborate(1-).