The molecular structures, chemical bonding and magnetochemistry of the three-coordinate iron(II) NHC complexes [(NHC)Fe{N(SiMe 3 ) 2 } 2 ] (NHC = IPr, 2; NHC = IMes, 3) are reported.N-Heterocyclic carbene (NHC) complexes of late transition metals such as ruthenium, palladium and gold are an intensely studied class of compound owing to their applications in catalysis. [1][2][3] In contrast, studies of iron NHC complexes are less widespread. A series of recent reports has, however, shown that NHC complexes of iron do have considerable potential for development in a range of carbon-carbon and carbonheteroatom bond forming reactions. 4 In most cases, the nature of the active iron NHC complex is not known, but it is probable that low-coordinate iron NHC complexes play an important role.