Table 2. Comparison of internal vibrational frequencies (cm−1) of α-FOX-7 from calculations and Raman measurement.
| DFT a | MP2 b | p-DFT c | p-DFT d | Exp. e | Assignment e |
|---|---|---|---|---|---|
| 57 | 58 | 119 | 123 | NO2 twist | |
| 92 | 108 | 151 | 194 | NO2 twist | |
| 115 | 131 | 193 | 233 | C—NH2 wag | |
| 203 | 155 | 270 | 253 | 246 | NO2 rock, NH2 wag |
| 280 | 276 | 317 | 316 | 318 | NO2 rock, NH2 twist |
| 299 | 311 | 324 | 331 | NH2, NO2 rock | |
| 320 | 387 | 378 | 397 | 400 | NH2 rock |
| 369 | 395 | 441 | 448 | 457 | NH2, NO2 rock |
| 378 | 437 | 443 | 477 | 472 | NH2 rock, NO2 twist, C—C st |
| 432 | 459 | 469 | 490 | 481 | NH2 twist, C—C st, NO2 sci |
| 454 | 481 | 598 | 634 | NH2 twist | |
| 454 | 491 | 610 | 646 | NH2 wag | |
| 590 | 593 | 633 | 676 | 622 | NH2 sci, twist |
| 605 | 618 | 658 | 681 | NH2 twist | |
| 666 | 625 | 668 | 695 | NH2 wag | |
| 704 | 690 | 715 | 723 | C—NO2 umb, NH2 twist | |
| 732 | 726 | 735 | 741 | 737 | C—NO2 umb, NH2 twist |
| 753 | 738 | 766 | 775 | 749 | NH2 rock, NO2 sci |
| 783 | 794 | 797 | 821 | 789 | NH2 twist |
| 841 | 862 | 833 | 843 | 856 | NO2 sci, C—C st, NH2 rock |
| 1041 | 1104 | 1006 | 1063 | 1024 | NH2 rock |
| 1049 | 1127 | 1050 | 1084 | 1070 | NH2 rock |
| 1106 | 1178 | 1106 | 1119 | 1142 | NH2 rock, NO2 st (sym) |
| 1172 | 1251 | 1141 | 1156 | 1165 | NH2 rock, C–C st |
| 1220 | 1378 | 1190 | 1201 | 1208 | C—NO2 st (asym), NH2 sci |
| 1287 | 1423 | 1300 | 1315 | 1311 | C—NO2 st (sym), NH2 rock |
| 1403 | 1538 | 1321 | 1339 | 1343 | NH2 sci, NO2 st (asym) |
| 1471 | 1588 | 1398 | 1411 | 1386 | NH2 rock, C—C st, NO2 st (asym) |
| 1505 | 1677 | 1480 | 1493 | 1506 | NH2 sci, C—C st |
| 1530 | 1714 | 1497 | 1519 | 1528 | NH2 sci, C—C rock |
| 1560 | 1752 | 1562 | 1599 | 1606 | NH2 sci, C—C st |
| 1581 | 1770 | 1603 | 1624 | 1630 | NH2 sci, C—C rock |
| 3341 | 3599 | 3288 | 3293 | 3299 | NH2 st (sym) |
| 3354 | 3609 | 3321 | 3334 | 3333 | NH2 st (sym) |
| 3544 | 3776 | 3418 | 3424 | 3405 | NH2 st (asym) |
| 3546 | 3776 | 3433 | 3450 | 3425 | NH2 st (asym) |
Notes: (a) DFT/B3LYP/6-311+G(2d,p) calculation in a vacuum; frequencies are scaled by a factor of 0.965 (this work). (b) MP2/6-31G(d,p) calculation in a vacuum; frequencies are scaled by a factor of 0.937 (Sorescu et al., 2001 ▸). (c)/(d) Periodic-DFT (p-DFT) calculation (Averkiev et al., 2014 ▸; Su et al., 2019 ▸) using CASTEP (Clark et al., 2005 ▸). (e) Raman measurement from solid sample with vibrational assignment: twist = twisting, wag = wagging, rock = rocking, scissor = scissoring, umb = umbrella, st = stretching, sym = symmetric and asym = asymmetric (Dreger et al., 2014 ▸).