Boron-linked groups are moved into or out of intimate contact with iro
n-bound ligands via conformational flips of the boroxime chelate rings
in Fe(DMGBR2)2 complexes, BR2 - BH2, BF2, BPh2, and BBN. Thermodynami
c and kinetic consequences of the dynamic linkage between macrocycle c
onformation and axial ligation to iron are described.