N-Functionalized Ferrocenes: Subvalent GroupXIV Element Chlorides and tert-Butyllithium-Induced C-C Bond Cleavage under Mild Conditions

The ferrocene derivative ((5)-Cp)Fe{(5)-C5H3-1-(ArNCH)-2-(CH2NMe2)} (1; Ar=2,6-iPr(2)C(6)H(3))) reacts diastereoselectively with LiR by carbolithiation and subsequent hydrolysis to give ((5)-Cp)Fe{(5)-C5H3-1-(ArHNCHR)-2-(CH2NMe2)} (3: R=tBu; 4: R=Ph; 5: R=Me) in high yields. For R=tBu, the organolithium derivative ((5)-Cp)Fe{(5)-C5H3-1-(ArLiNCHR)-2-(CH2NMe2)} (2) was isolated. Compound 2 reacts with GeCl(2)dioxane and SnCl2 to give the metallylene amide chlorides ((5)-Cp)Fe{(5)-C5H3-1-(ArMNCHtBu)-2-(CH2NMe2)} 6 (M=GeCl) and 7 (M=SnCl), respectively, which each contain three stereogenic centers. The potential of 7 as a ligand in transition-metal chemistry is demonstrated by formation of its complex ((5)-Cp)Fe{(5)-C5H3-1-(ArMNCHtBu)-2-(CH2NMe2)} [9, M= Sn(Cl)W(CO)(5)]. Treatment of 3 with tert-butyllithium at room temperature causes an unprecedented carbon-carbon bond cleavage whereas under kinetic control, lithiation at the Cp-3 position takes place, which leads to the isolation of ((5)-Cp)Fe{(5)-C5H3-1-(ArHNCHtBu)-2-(CH2NMe2)-3-SiMe3} (10).