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Protonated oxalyl chloride and the ClCO+ cation
Sebastian Steiner1, Kristina Djordjevic1, Valentin Bockmair1
1Department Chemie, Ludwig-Maximilians Universität, Butenandtstrasse 5-13 (Haus D), D-81377 München, Germany.
Abstract:
The reactions of oxalyl chloride were investigated in the binary superacidic systems HF/SbF5 and DF/SbF5. O-Monoprotonated oxalyl chloride was isolated and represents the first example of a protonated acyl chloride. Diprotonated oxalyl chloride is only stable in solution. Salts of the ClCO+ cation were synthesized from the reactions of oxalyl chloride or COClF with SbF5 in 1,1,1,2-tetrafluoroethane (R-134a, CF3CFH2). The colourless salts were characterized by low-temperature vibrational spectroscopy, NMR spectroscopy and single-crystal X-ray diffraction. (1,2-Dichloro-2-oxoethylidene)oxidanium hexafluoridoantimonate(V), [C2O(OH)Cl2][SbF6], crystallizes in the monoclinic space group P21 and carbonyl chloride hexadecafluoridotriarsenate(V) [ClCO][Sb3F16], in the trigonal space group P31, with two and three formula units per unit cell, respectively. Monoprotonated oxalyl chloride and the ClCO+ cation both display very short C-Cl bonds with a strong double-bond character.
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