[mohamed]

In my textbook, the author states that methyl iodide is a very soft electrophile so it causes C-alkylation when it reacts with an enolate since the C-site is softer than the O-site unlike methyl fluoride which does the opposite, but when I try to draw the MO diagram of methyl iodide I notice that the occupied orbitals are soft and not nearly as concentrated on the iodine  as they are concentrated on the fluorine and LUMO has the opposite contribution so the MO at carbon in case of fluorine would be bigger and softer than that in case of iodine so why does enolate carbon prefer methyl iodide although methyl fluoride carbon has bigger MO contribution to LUMO?