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13 C‐MAS‐NMR Spectra of Technical Calcium Carbide and Barium Carbide—Are the C 2 2⊖ Ions in Ionic Carbides Surrounded Symmetrically?
Author(s) -
Wrackmeyer Bernd,
Horchler Klaus,
Sebald Angelika,
Merwin Lawrence H.,
Ross Charles
Publication year - 1990
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199008071
Subject(s) - carbide , barium , ionic bonding , materials science , ion , crystallography , nmr spectra database , nuclear magnetic resonance spectroscopy , spectral line , chemistry , stereochemistry , physics , metallurgy , organic chemistry , astronomy
The answer to the question posed by the title is no. Whereas δ( 13 C) ≈ 140 for a “free” C 2 2⊖ion, values of 206.2 and 232.1 are found for the ionic carbides CaC 2 and BaC 2 , respectively, in the solid state. Furthermore, simulation of the 13 C MAS NMR spectra shows unambiguously that the C 2 units deviate from axial symmetry. For CaC 2 , the presence of a second phase, identified from X‐ray powder patterns, was confirmed by NMR spectroscopy.