Coordination and Organometallic diamido-donor Iron and Cobalt Complexes

The structures, reactivity and magnetic properties of high-spin iron and cobalt complexes of diamido donor ligands were investigated. Unusual multinuclear, halidebridged Fe(II) and Co(II) complexes with the basic dinuclear unit M 2X2[tBuNON] (X= Br, M= Fe (1), Co (2); X= Cl, M= Fe (3), Co (4)), ([tBuNON]2-= [Me3CN(SiMe2)] 2O2-) were synthesized, structurally and magnetically characterized. The reduction reaction of 3 with KC8 and addition of CO and dmpe (Me2P(CH2)2PMe 2) generated {Fe2[tBuNON]}2 and, with dmpe also FeCl2(dmpe)2. However, the addition of 1,3-bis-(2,4,6- trimethylphenyl)imidazol-2-ylidene (NHC) carbene to 3 resulted in the new {[NHC]FeCl2}2.;Alkyl for halide metathesis via the reaction of LiCH2SiMe3 in 1-4 generated rare high-spin mixed alkyl/halide {[tBuNON]M 2X(CH2SiMe3)2}2 ( 8-11) complexes and unusual high-spin dialkyl dinuclear iron and cobalt complexes of the form {M2(CH2SiMe3) 2[tBuNON]} (M = Fe (6) and Co ( 7 )); reaction with MeLi to form the dimethyl analogue was not successful, while addition of one equivalent of methyl reagent per dinuclear unit in 3 and 4 resulted in {Fe2Br(Me)[tBu NON]} 2 and {Co2Cl(Me)[tBuNON]} 2. Neither 6 nor 7 act as polymerization catalysts for ethylene; addition of B(C6F5)3 as a cocatalyst was found to further hinder any activity of 6 and 7 by the formation of {Co2(C 6F5) 2[tBuNON]} and {Fe2 Cl(C 6F 5)[tBuNON]}2. Upon exposing 6 to excess CO, a rare dicarbamoyl trinuclear iron complex was obtained, which results from CO binding, isocarbonyl binding and Fe-C and Fe-N CO insertions.;Attempts towards obtaining highoxidation state iron and cobalt complexes with strong oxidizing agents showed that the [NON] ligand did not support such systems. Addition of benzyl bromide to {Fe[Me3PhNON]} 2 resulted in {FeBr[Me3Ph NON]}2 and reaction v of {FeCl[tBuNON]} 2 with dmpe led to a rare tetrahedral iron(III) complex {FeCl[ tBuNON]}2(mu-Me2 PCH2CH2PMe 2).;To overcome potential difficulties with limited Si-N bond stabilities, carbonbackbone diamido {M[iPrNNOEN]}2 and {M[ iPrNOOEN]}2 (M= Fe, Co) [MeN((CH 2) 2N.iPr)2] ([iPrNOOEN] 2.) and [O((CH2)2N.iPr)2] ([ iPrNNOEN] 2.) were synthesized, structurally characterized and compared with similar diamido Fe(II) and Co(II) complexes. Monomeric diamine complexes {MCl 2[H2 iPrNNOEN]} (M= Fe; Co) and {FeCl 2[H2 iPrNOOEN]} were obtained from oxidations of the diamido precursors.;All complexes described were characterized by elemental analysis, 1H NMR spectroscopy and single crystal X-ray diffraction and, in some cases by SQUID magnetometry.