A series of (di)picolinic acids and their derivates are investigated as novel complexing tridentate or bidentate ligands in the iron-mediated reverse atom transfer radical polymerization of methyl methacrylate in N,N-dimethylformamide at 100 degrees C with 2,2'-azobisisobutyrontrile as an initiator. The polymerization rates and polydispersity indices (1.32-1.8) of the resulting polymers are dependent on the structures of the ligands employed. Different iron complexes may be involved in iron-mediated reverse atom transfer radical polymerization, depending on the type of acid used. H-1 NMR spectroscopy has been used to study the structure of the resulting polymers. Chain-extension reactions have been performed to further confirm the living nature of this catalytic system. (c) 2006 Wiley Periodicals, Inc.