Heteroleptic, two-coordinate [M(NHC){N(SiMe3)2}] (M = Co, Fe) complexes: synthesis, reactivity and magnetism rationalized by an unexpected metal oxidation state12. Issue 4 (5th January 2017) - Danopoulos, Andreas A.
Abstract : Magnetism, XPS and XANES data of the title complexes imply M II centres coupled to one ligand-delocalized electron. Abstract : The linear, two-coordinate and isostructural heteroleptic [M(IPr){N(SiMe3 )2 }] (IPr = 1, 3-bis(diisopropylphenyl)-imidazol-2-ylidene), formally M I complexes (M = Co, 3 ; Fe, 4 ) were obtained by the reduction of [M(IPr)Cl{N(SiMe3 )2 }] with KC8, or [Co(IPr){N(SiMe3 )2 }2 ] with mes*PH2, mes* = 2, 4, 6- t Bu3 C6 H2 . The magnetism of3 and4 implies Co II and Fe II centres coupled to one ligand-delocalized electron, in line with XPS and XANES data; the ac susceptibility of4 detected a pronounced frequency dependence due to slow magnetization relaxation. Reduction of [Fe(IPr)Cl{N(SiMe3 )2 }] with excess KC8 in toluene gave the heteronuclear 'inverse-sandwich' Fe–K complex7, featuring η 6 -toluene sandwiched between one Fe 0 and one K + centre.