Bis(imino)pyridine Ligand Deprotonation Promoted by a Transient Iron Amide

Addition of 2 equiv of LiNMe2 to the bis(imino)pyridine ferrous
dichloride, (iPrPDI)FeCl2 (iPrPDI = (2,6-iPr2−C6H3NCMe)2C5H3N),
resulted in deprotonation of the chelate methyl groups, yielding
the bis(enamide)pyridine iron dimethylamine adduct, (iPrPDEA)Fe(NHMe2) (iPrPDEA = (2,6-iPr2−C6H3NCCH2)2C5H3N). Performing
a similar procedure with KN(SiMe3)2 in THF solution afforded the
corresponding bis(THF) adduct, (iPrPDEA)Fe(THF)2. (iPrPDEA)Fe(NHMe2) has also been prepared by addition of the free amine to
the iron dialkyl complex, (iPrPDI)Fe(CH2SiMe3)2, implicating formation of a transient iron amide that is sufficiently basic to deprotonate
the bis(imino)pyridine methyl groups. Deprotonation of the amine
ligand in (iPrPDEA)Fe(NHMe2) has been accomplished by addition
of amide bases to afford the ferrous amide-ate complexes,
[(iPrPDEA)Fe(μ-NMe2)M] (M = Li, K).