Table 2.
Optimized geometrical parameters of NE monomers (C'NE ₋ C‴NE), ZW monomer (CZW) and dimer (D1) of DL-3-Aminoisobutyric acid.
| Parameters | C'NE | C″NE | C‴NE | CZW | D1 | Expta |
|---|---|---|---|---|---|---|
| Bond length (Å) | ||||||
| 1C–2O | 1.206 | 1.206 | 1.206 | 1.264 | 1.256 | 1.247 |
| 1C–3O/17C–19O∗ | 1.358 | 1.359 | 1.360 | 1.264 | 1.272/1.263∗ | 1.251 |
| 1C–7C | 1.514 | 1.516 | 1.515 | 1.544 | 1.540 | 1.520 |
| 3O–16H | 0.969 | 0.969 | 0.969 | -- | -- | -- |
| 9C–4N/25C–20N∗ | 1.467 | 1.465 | 1.465 | 1.507 | 1.507/1.499∗ | 1.484 |
| 9C–7C | 1.538 | 1.550 | 1.544 | 1.527 | 1.527 | 1.522 |
| 9C–14H | 1.098 | 1.099 | 1.100 | 1.088 | 1.088 | 1.000 |
| 9C–15H | 1.092 | 1.093 | 1.092 | 1.088 | 1.088 | 1.020 |
| 4N–5H/20N–21H∗ | 1.015 | 1.014 | 1.015 | 1.023 | 1.022/1.063∗ | 0.960 |
| 4N–6H/20N–22H∗ | 1.013 | 1.013 | 1.013 | 1.023 | 1.023/1.022∗ | 1.050 |
| 4N–16H/20N–32H∗ | -- | -- | -- | 1.023 | 1.023/1.022∗ | 0.970 |
| 8C–7C | 1.542 | 1.530 | 1.538 | 1.539 | 1.539 | 1.528 |
| 8C–11H | 1.091 | 1.092 | 1.092 | 1.092 | 1.092 | 0.970 |
| 8C–12H | 1.090 | 1.090 | 1.090 | 1.094 | 1.093 | 1.060 |
| 8C–13H | 1.093 | 1.092 | 1.092 | 1.093 | 1.093 | 1.010 |
| 7C–10H | 1.095 | 1.094 | 1.093 | 1.094 | 1.094 | 0.980 |
| RMSD | 0.0700 | 0.0704 | 0.0704 | 0.0619 | 0.0649 | |
| Bond angle (in deg) | ||||||
| 2O–1C–3O | 122.0 | 121.9 | 121.8 | 125.2 | 124.8 | 124.3 |
| 2O–1C–7C | 125.9 | 125.9 | 125.8 | 118.0 | 117.6 | 118.0 |
| 3O–1C–7C | 111.9 | 111.9 | 112.2 | 116.7 | 117.4 | 117.6 |
| 1C–3O–16H | 107.0 | 107.0 | 107.0 | -- | -- | -- |
| 4N–9C–7C/20N–25C–23C∗ | 110.3 | 110.3 | 110.1 | 111.3 | 111.3/111.9∗ | 112.3 |
| 4N–9C–14H | 113.4 | 113.2 | 113.2 | 105.9 | 106.0 | 104.5 |
| 4N–9C–15H | 108.3 | 108.2 | 108.2 | 106.5 | 106.5 | 106.5 |
| 7C–9C–14H | 109.0 | 109.1 | 109.0 | 111.4 | 111.3 | 112.5 |
| 7C–9C–15H | 108.8 | 108.4 | 108.9 | 112.2 | 112.2 | 111.0 |
| 15H–9C–14H | 106.5 | 107.2 | 107.0 | 108.9 | 108.9 | 109.0 |
| 9C–4N–5H | 111.1 | 111.1 | 111.1 | 110.9 | 110.5 | 108.0 |
| 9C–4N–6H | 110.9 | 111.1 | 111.0 | 110.5 | 111.6 | 106.7 |
| 9C–4N–16H | -- | -- | -- | 111.7 | 111.0 | 112.6 |
| 5H–4N–6H | 107.1 | 107.4 | 107.3 | 107.9 | 107.6 | 106.0 |
| 5H–4N–16H | -- | -- | -- | 107.7 | 107.9 | 111.0 |
| 6H–4N–16H | -- | -- | -- | 107.7 | 107.9 | 110.0 |
| 7C–8C–11H | 111.2 | 111.2 | 111.1 | 110.2 | 110.3 | 110.0 |
| 7C–8C–12H | 109.0 | 109.3 | 109.1 | 111.9 | 111.6 | 112.0 |
| 7C–8C–13H | 110.5 | 110.4 | 110.8 | 110.8 | 110.8 | 109.0 |
| 11H–8C–12H | 109.1 | 108.8 | 108.7 | 107.1 | 107.1 | 107.0 |
| 11H–8C–13H | 108.5 | 107.9 | 108.3 | 108.3 | 108.4 | 110.0 |
| 12H–8C–13H | 108.2 | 108.9 | 108.5 | 108.1 | 108.2 | 106.0 |
| 1C–7C–9C | 110.4 | 108.1 | 110.7 | 110.4 | 110.5 | 113.2 |
| 1C–7C–8C | 109.3 | 111.4 | 111.1 | 109.0 | 109.1 | 108.6 |
| 1C–7C–10H | 107.2 | 107.2 | 104.9 | 107.1 | 106.7 | 109.4 |
| 9C–7C–8C | 112.3 | 112.1 | 112.2 | 112.8 | 112.9 | 109.6 |
| 9C–7C–10H | 109.1 | 107.4 | 108.3 | 108.4 | 108.5 | 108.1 |
| 8C–7C–10H | 108.2 | 110.2 | 109.1 | 108.7 | 108.6 | 109.8 |
| RMSD | 3.4560 | 3.5830 | 3.5062 | 1.7860 | 1.8596 | |
| Dihedral angle (in deg) | ||||||
| 16H–3O–1C–2O | -1.3 | 0.8 | 0.3 | -- | -- | -- |
| 14H–9C–4N–6H | 72.3 | 73.5 | 71.8 | -60.1 | -60.84 | -- |
| 10H–7C–1C–2O | -145.3 | 157.0 | 4.8 | -149.6 | -146.5 | -- |
| Hydrogen bonding parameters | ||||||
| 20N–21H (r) | -- | -- | -- | -- | 1.063 | 1.050 |
| 21H⋯3O (d) | -- | -- | -- | -- | 1.663 | 1.730 |
| 20N⋯3O (D) | -- | -- | -- | -- | 2.721 | 2.758 |
| 20N–21H⋯3O (θ) | -- | -- | -- | -- | 172.9 | 166.0 |
a
XRD data of DL-3-Aminoisobutyric acid monohydrate [39].