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Heteroleptic, two-coordinate [M(NHC){N(SiMe3)2}] (M = Co, Fe) complexes: synthesis, reactivity and magnetism
Andreas A Danopoulos1, Pierre Braunstein2, Kirill Yu Monakhov3
1Institute for Advanced Study (USIAS), Université de Strasbourg, 67081 Strasbourg Cedex, France. danopoulos@unistra.fr and Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, Institut de Chimie, 4 rue Blaise Pascal, 67081 Strasbourg Cedex, France. braunstein@unistra.fr.
Abstract:
The linear, two-coordinate and isostructural heteroleptic [M(IPr){N(SiMe3)2}] (IPr = 1,3-bis(diisopropylphenyl)-imidazol-2-ylidene), formally MI 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-tBu3C6H2. The magnetism of 3 and 4 implies CoII and FeII centres coupled to one ligand-delocalized electron, in line with XPS and XANES data; the ac susceptibility of 4 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 complex 7, featuring η6-toluene sandwiched between one Fe0 and one K+ centre.
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