Table 6.
Effect of substituting a trifluoromethyl group for methyl on different heteroatoms.
| Atom/group Y-CX3 (X = H, F) | Allred-Rochow Electronegativity | C-Y bond length in Å | Δr = r(CF3)–r(CH3) in Å | |
| X = H | X = F | |||
| P-(CX3) | 2.06 | 1.844 | 1.904 | +0.060 |
| H-(CX3) | 2.20 | 1.099 | 1.102 | +0.003 |
| I-(CX3) | 2.21 | 2.139 | 2.138 | −0.001 |
| S-(CX3) | 2.44 | 1.805 | 1.819 | +0.014 |
| Se-(CX3) | 2.48 | 1.945 | 1.980 | +0.035 |
| Br-(CX3) | 2.74 | 1.939 | 1.923 | −0.016 |
| Cl-(CX3) | 2.83 | 1.781 | 1.752 | −0.029 |
| N-(CX3) | 3.07 | 1.458 | 1.426 | −0.032 |
| O-(CX3) | 3.50 | 1.416 | 1.369 | −0.047 |
| F-(CX3) | 4.10 | 1.385 | 1.319 | −0.066 |