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The infrared and Raman spectra of isoelectronic potassium imidosulphonate, K 2 NH(SO 3 ) 2 and potassium methylenedisulphonate, K 2 CH 2 (SO 3 ) 2
Author(s) -
Hall John R.,
Johnson Robert A.
Publication year - 1981
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250110412
Subject(s) - chemistry , raman spectroscopy , spectral line , potassium , infrared spectroscopy , crystallography , hydrogen bond , infrared , crystallite , analytical chemistry (journal) , molecule , physics , organic chemistry , chromatography , astronomy , optics
The polycrystalline IR and Raman spectra (4000–50 cm −1 ) of isoelectronic K 2 NH(SO 3 ) 2 and K 2 CH 2 (SO 3 ) 2 have been recorded at 77 K. These salts are isomorphous at ambient temperature (space group C 2/ c ( C 2h 6 )) but K 2 NH(SO 3 ) 2 undergoes a phase change on cooling to 77 K. Possible low‐temperature structures for the latter are proposed and their predicted spectra are compared with the observed spectra. The phase change appears to be limited to an ordering of hydrogen atoms to give a structure with space symmetry P 1( C 1 1 ) with Z = 4. To assist with the band assignment, spectra of the 2 H analogues of both salts and the 15 N analogue of K 2 NH(SO 3 ) 2 have been recorded. Aqueous solution spectra, including qualitative Raman polarization data have also been obtained for the highly soluble salts (NH 4 ) 2 NH(SO 3 ) 2 and Na 2 CH 2 (SO 3 ) 2 ·2.5H 2 O and their 2 H analogues. For NH(SO 3 ) 2 2− , the skeletal modes are assigned frequencies of 858 cm −1 (ν asym NS), 842 cm −1 (ν sym NS) and c. 180 cm −1 (δNS 2 ). The corresponding CH 2 (SO 3 ) 2 2− frequencies are 800 cm −1 (ν asym CS), 776 cm −1 (ν sym CS) and c. 180 cm −1 (δCS 2 ). The SO 3 groups show their characteristic frequencies which are very similar for both species.