Disparate reactivity from isomeric {Me2C(CH2NCHpy)2} and {Me2C(CHNCH2py)2} chelates in iron complexation

Two isomeric tetradentate chelates have led to disparate chemistry with iron: Fe{N(TMS)2}2(THF) catalyzed the cyclization of Me2C(CNCH2(2-py))2 to 4,4-dimethyl-2-(pyridin-2-yl)-N-(pyridin-2-ylmethylene)pyrrolidin-3-amine, whereas Me2C(CH2NCH(2-py)2 (dmp(PI)2) generated {dmp(PI)2}FePMe3 (Fe-PMe3) when treated with (Me3P)3HFe(η2-PMe2CH2).96