Table 3.
Calculated geometrical parameters for the free base, cationic and hydrochloride tacrine species in gas and aqueous solution by using the B3LYP/6-311G* method compared with the experimental for the hydrochloride species of tacrine in solid phase.
| B3LYP/6-311G*a | Expb | ||||||||||||
| Parameters | Free base | Cationic | Hydrochloride | ||||||||||
| Form I | Form I | Form III | |||||||||||
| Gas | Water | Gas | Water | Gas | Water | Gas | Water | ||||||
| Bond lengths (Å)rowhead | |||||||||||||
| N1–H30 | 1.012 | 1.013 | 1.090 | 1.033 | 1.009 | 1.014 | 0.898 | ||||||
| N1–C8 | 1.320 | 1.328 | 1.351 | 1.349 | 1.334 | 1.348 | 1.365 | 1.350 | 1.353 | ||||
| N1–C11 | 1.358 | 1.361 | 1.376 | 1.372 | 1.366 | 1.372 | 1.374 | 1.373 | 1.361 | ||||
| N2–H26 | 1.007 | 1.008 | 1.005 | 1.007 | 1.005 | 1.007 | 1.077 | 1.018 | 0.866 | ||||
| N2–H27 | 1.007 | 1.008 | 1.005 | 1.007 | 1.004 | 1.006 | 1.008 | 1.007 | 0.897 | ||||
| N2–C9 | 1.385 | 1.374 | 1.341 | 1.337 | 1.361 | 1.339 | 1.315 | 1.334 | 1.333 | ||||
| C9–C10 | 1.431 | 1.435 | 1.443 | 1.446 | 1.437 | 1.445 | 1.460 | 1.449 | 1.437 | ||||
| C9–C6 | 1.393 | 1.399 | 1.419 | 1.419 | 1.405 | 1.416 | 1.438 | 1.421 | 1.419 | ||||
| C6–C4 | 1.517 | 1.517 | 1.516 | 1.514 | 1.516 | 1.514 | 1.512 | 1.514 | 1.482 | ||||
| C10–C12 | 1.418 | 1.419 | 1.415 | 1.415 | 1.416 | 1.415 | 1.411 | 1.415 | 1.446 | ||||
| H26–Cl31 | 1.853 | 2.194 | 1.898 | 2.363 | 2.401 | ||||||||
| RMSD | 0.775 | 0.775 | 0.727 | 0.727 | 0.184 | 0.093 | 0.172 | 0.069 | |||||
| Bond angles (°)rowhead | |||||||||||||
| H30–N1–C8 | 118.1 | 118.2 | 119.1 | 118.9 | 118.3 | 118.4 | 115.5 | ||||||
| H30–N1–C11 | 117.8 | 117.9 | 117.8 | 118.0 | 118.2 | 118.0 | 121.7 | ||||||
| C8–N1–C11 | 118.2 | 118.0 | 124.0 | 123.7 | 122.9 | 123.0 | 123.3 | 123.4 | 122.6 | ||||
| C6–C9–C10 | 119.0 | 118.7 | 120.0 | 119.5 | 119.8 | 119.4 | 118.5 | 119.1 | 118.9 | ||||
| N2–C9–C10 | 120.0 | 120.5 | 120.3 | 120.3 | 119.9 | 120.5 | 121.1 | 120.2 | 120.0 | ||||
| N2–C9–C6 | 120.8 | 120.6 | 119.6 | 120.0 | 120.1 | 120.0 | 120.2 | 120.5 | 121.0 | ||||
| H26–N2–H27 | 112.2 | 112.6 | 116.3 | 116.6 | 115.4 | 116.4 | 111.7 | 114.8 | 112.9 | ||||
| N2–H26–Cl31 | 177.9 | 176.6 | 166.8 | 153.6 | 160.9 | ||||||||
| RMSD | 82.2 | 82.2 | 56.9 | 56.9 | 6.4 | 6.4 | 6.0 | 2.7 | |||||
| Dihedral angles (°)rowhead | |||||||||||||
| C9–N2–H26–Cl31 | −124.2 | −169.9 | 154.4 | 179.6 | −164.1 | ||||||||
| N2–C9–C6–C8 | −178.9 | −179.4 | −176.8 | −178.0 | −178.0 | −176.0 | −175.2 | −177.5 | −176.9 | ||||
| N1–C8–C6–C4 | −178.8 | −179.6 | 179.7 | 179.8 | −179.3 | 179.6 | 178.7 | −179.7 | 178.9 | ||||
| N1–C11–C10–C12 | −178.5 | −179.3 | 179.9 | 179.2 | −179.0 | −179.5 | −179.5 | 179.9 | −179.9 | ||||
| N1–C8–C7–C5 | 159.9 | 160.4 | 161.9 | 161.6 | 161.1 | 162.0 | 163.9 | 161.9 | 164.5 | ||||
| N1–C11–C13–C15 | 179.3 | 179.6 | −179.8 | −179.3 | 179.6 | 179.8 | 179.7 | −179.9 | −165.9 | ||||
| RMSD | 213.7 | 214.0 | 161.5 | 161.3 | 203.8 | 141.2 | 191.9 | 250.5 | |||||
a
This work.
b
Ref [23] for orthorhombic pseudopolymorph for tacrine hydrochloride.