Raman spectra and crystal structure of polycrystalline tetramethylammonium salts

Abstract

The Raman spectra of eight polycrystalline Me4" salts have been measured and are discussed in relation to crystal structures. In most of the salts, several degenerate bands of the cation show splittings due to site symmetries lower than Td. From the spectral shapes in the methyl deformation and stretching region and the intensity ratio of the two NC4 skeletal deformation modes, the extent of cation distortion in each particular salt can be deduced. These distortions are strongest in the halides, whereas no significant crystal field effects are found in the SnCI:-and CdCI; salts. Anion Raman bands and frequencies of lattice modes are also reported.

Synthesis, vibrational and NMR spectroscopic characterization of [N(CH3)4][IO2F2] and X-ray crystal structure of [N(CH3)4]2[IO2F2][HF2]

“…The F Á Á Á F distance in trans-Ru(dmpe) 2 (H)(F Á Á Á HF) of 2.286(8) Å is close to that of ionic bifluoride, however, 1 H and 19 F NMR spectroscopic results favor a hydrogen-bonded description [27]. The number of structurally characterized compounds containing bridging hydrogen fluoride molecules is limited to the dimeric niobium and osmium species, [(h 5 -C 5 Me 5 )NbF 4 (HF)AsF 3 ] 2 [28] (14) 3020 (19) 2968 (16) n(CH 3 ) and binary bands 2933(13) 2897 (7) 2837 (11) a The Raman spectrum was recorded on a single crystal inside a glass Lindemann capillary at room temperature using 514.5 nm excitation. Values in parentheses denote relative Raman intensities; and sh a shoulder.…”

“…The bending of the axial ligands in the pseudotrigonal bipyramidal AX 2 Y 2 E structures towards the lonepair position has also been found in the crystal structures of XeO 2 F 2 (174.7(4)8) [19], XeO 2 F 2 ÁTcO 2 F 3 (175.7(6)8) [20], and XeO 2 (OTeF 5 ) 2 (163.7(2)8) [21], and, in the case of XeO 2 F 2 , has been attributed to a non-spherical charge distribution of the lone pair, which is more extended in the equatorial plane and seems to reduce the repulsive } (2) 99(3) Lattice modes 84 (2) a Abbreviations denote shoulder (sh), very strong (vs), strong (s), medium (m), weak (w), very weak (vw), and broad (br). b The NðCH 3 Þ þ 4 cation modes were observed in the Raman spectrum (À100 8C) at 376 (1), 384(1), n 8 (E); 456 (2), n 19 (T 2 ); 756 (7), n 3 (A 1 ); 942 sh, 947 (10), 950 sh, n 18 (T 2 ); 1174(1), 1179(2), n 7 (E); 1292(1), n 17 (T 2 ); 1398(2), 1405(2), 1409(1), n 16 (T 2 ); 1457 (1), 1469(16), 1474(14), n 2 (A 1 ), n 6 (E); 2788(2), 2804(1), 2807 (1), 2899(1) 2907(1), 2960(8), 2975 sh, 2990(2), 3001(2), 3032(6), 3037(5), 3043 (8), 3059(7) cm À1 , n(CH 3 ) and binary bands [15,16]. c The NðCH 3 Þ þ 4 cation modes were observed in the infrared spectrum at 922 w, 949 s, n 18 (T 2 ); 1063 vw, 1182 vw, 1199 vw, n 7 (E); 1240 w, 1290 w, n 17 (T 2 ); 1402 m, 1411 m, n 16 (T 2 ); 1450 w, 1468 w, 1486 s, 1493 s, n 2 (A 1 ), n 6 (E); 1783 br vw, 2042 vw, 2161 vw, 2237 vw, 2349 w, 2480 w, 2515 w, 22575 w, 2619 vw, 2697 vw, 2747w, 2793 w, 2852 w, 2923 w, 2969 w, 3043 m, 3056 m, 3099 w, 3135 w, 3416 w, 3495 w cm À1 , n(CH 3 ) and binary bands [15,16].…”

“…b The NðCH 3 Þ þ 4 cation modes were observed in the Raman spectrum (À100 8C) at 376 (1), 384(1), n 8 (E); 456 (2), n 19 (T 2 ); 756 (7), n 3 (A 1 ); 942 sh, 947 (10), 950 sh, n 18 (T 2 ); 1174(1), 1179(2), n 7 (E); 1292(1), n 17 (T 2 ); 1398(2), 1405(2), 1409(1), n 16 (T 2 ); 1457 (1), 1469(16), 1474(14), n 2 (A 1 ), n 6 (E); 2788(2), 2804(1), 2807 (1), 2899(1) 2907(1), 2960(8), 2975 sh, 2990(2), 3001(2), 3032(6), 3037(5), 3043 (8), 3059(7) cm À1 , n(CH 3 ) and binary bands [15,16]. c The NðCH 3 Þ þ 4 cation modes were observed in the infrared spectrum at 922 w, 949 s, n 18 (T 2 ); 1063 vw, 1182 vw, 1199 vw, n 7 (E); 1240 w, 1290 w, n 17 (T 2 ); 1402 m, 1411 m, n 16 (T 2 ); 1450 w, 1468 w, 1486 s, 1493 s, n 2 (A 1 ), n 6 (E); 1783 br vw, 2042 vw, 2161 vw, 2237 vw, 2349 w, 2480 w, 2515 w, 22575 w, 2619 vw, 2697 vw, 2747w, 2793 w, 2852 w, 2923 w, 2969 w, 3043 m, 3056 m, 3099 w, 3135 w, 3416 w, 3495 w cm À1 , n(CH 3 ) and binary bands [15,16]. d Values are from [10].…”

The solid-state 19F NMR spectrum of [N(CH3)4][IO2F2], a vibrational study of [N(CH3)4][IO3] and [N(CH3)4][IO3]·2H2O, and the X-ray crystal structures of [N(CH3)4][IO2F2] and [N(CH3)4][IO3]

“…Hydrogen bonding effectively reduces the negative charge on the anion, making the I-O bonds less polar in the dihydrate when compared with the anhydrous salt. As in the case of the anhydrous salt, the only degenerate E-mode of IO 3 À that is split in the low-temperature Raman spectrum is n 3 (E [14]. d Values are from [10].…”

“…d Values are from [10]. e The N(CH 3 ) 4 + cation modes were observed in the Raman spectrum (À100 8C) at n 8 (E), 367(4), 371 sh; n 19 (T 2 ), 457(5); n 3 (A 1 ), 757(37); n 18 (T 2 ), 953 (7), 956(9), 961(9); n 7 (E), 1177(1), 1181(2); n 17 (T 2 ), 1291(1); n 16 (T 2 ), 1418(2); n 2 (A 1 ), n 6 (E), 1436(1), 1458 (14), 1469(7); n(CH 3 ) and combination bands, 2820 (5) 2905 (3), 2925 (7), 2959 (7), 2980(4), 3012(4), 3019(5), 3027(11), 3033(10), 3041(10) cm À1 [14]. f Values are from [12].…”