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Synthesis and Characterization of 2‐Mono‐ and 1,2‐Diaminocarba‐ closo ‐dodecaborates M[1‐R‐2‐H 2 N‐ closo ‐CB 11 H 10 ] (R=H, Ph, H 2 N, CyHN)
Author(s) -
Finze Maik
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801497
Subject(s) - chemistry , raman spectroscopy , crystallography , differential scanning calorimetry , nuclear magnetic resonance spectroscopy , stereochemistry , physics , optics , thermodynamics
The first primary 2‐aminocarba‐ closo ‐dodecaborates [1‐R‐2‐H 2 N‐ closo ‐CB 11 H 10 ] − (R=H ( 1 ), Ph ( 2 )) have been synthesized by insertion reactions of (Me 3 Si) 2 NBCl 2 into the trianions [7‐R‐7‐ nido ‐CB 10 H 10 ] 3− . The difunctionalized species [1,2‐(H 2 N) 2 ‐ closo ‐CB 11 H 10 ] ( 3 ) and 1‐CyHN‐2‐H 3 N‐ closo ‐CB 11 H 10 (H‐ 4 ) have been prepared analogously from (Me 3 Si) 2 NBCl 2 and 7‐H 3 N‐7‐ nido ‐CB 10 H 12 . In addition, the preparation of [Et 4 N][1‐H 2 N‐2‐Ph‐ closo ‐CB 11 H 10 ] ([Et 4 N]‐ 5 ) starting from PhBCl 2 and 7‐H 3 N‐7‐ nido ‐CB 10 H 12 is described. Methylation of the [1‐Ph‐2‐H 2 N‐ closo ‐CB 11 H 10 ] − ion ( 2 ) to produce 1‐Ph‐2‐Me 3 N‐ closo ‐CB 11 H 10 ( 6 ) is reported. The crystal structures of [Et 4 N]‐ 2 , [Et 4 N]‐ 5 , and 6 were determined and the geometric parameters were compared to theoretical values derived from DFT and ab initio calculations. All new compounds were studied by NMR, IR, and Raman spectroscopy, MALDI mass spectrometry, and elemental analysis. The discussion of the experimental NMR chemical shifts and of selected vibrational band positions is supported by theoretical data. The thermal properties were investigated by differential scanning calorimetry (DSC). The p K a values of 2‐H 3 N‐ closo ‐CB 11 H 11 (H‐ 1 ), 1‐H 3 N‐ closo ‐CB 11 H 10 (H‐ 7 ), and 1,2‐(H 3 N) 2 ‐ closo ‐CB 11 H 10 (H 2 ‐ 3 ) were determined by potentiometric titration and by NMR studies. The experimental results are compared to theoretical data (DFT and ab initio). The basicities of the aminocarba‐ closo ‐dodecaborates agree well with the spectroscopic and structural properties.