Amino pyridine iron(II) complexes: Characterization and catalytic application for atom transfer radical polymerization and catalytic chain transfer

Crystallographic Evidence of η1-Coordination of Bulky Aminopyridine in Halide-Containing Iron (II) Complexes

Reaction of N-(2,6-diisopropylphenyl)-[6-(2,4,6-triisopropylphenyl)-pyridine-2-yl]-amine (ApH) in equimolar ratio with anhydrous FeBr2 and FeI2 in tetrahydrofuran (THF) afforded, after workup in toluene, the first examples of mono(aminopyridine) Fe(II) complexes, [ApHFeBr(µ-Br)]2 (1) and [ApHFeI2(thf)] (2), respectively. X-ray analysis shows 1 to be dimeric, whereas compound 2 is monomeric. In both cases, aminopyridine ligands show rare η1-coordination to Fe through pyridine nitrogen atom. Compound 1 exhibits intramolecular N–H⋯Br hydrogen bonds [3.363 Å] with an N–H⋯Br angle of 158.84°. Hirshfeld surface and fingerprint plots identify the significant intermolecular interactions in the crystal network. Both compounds crystallized in the monoclinic space group. For compound 1, C2/c, the cell parameters are: a  =  25.5750(5) Å, b  =  10.5150(5) Å, c = 18.9610(8) Å, β  =  97.892(5)°, V  =  5050.7(3) A3, Z  =  4. For compound 2, P21/c, the cell parameters are: a  =  10.3180(7) Å, b  =  16.1080(10) Å, c  =  18.6580(11) Å, β  =  102.038(5)°, V  = 3032.8(3) A3, Z  =  4.