Web Release Date: December 19,
Synthesis, Reactivity, and Solid State Structures of Four-Coordinate Iron(II) and Manganese(II) Alkyl Complexes
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853
Received September 23, 2003
Abstract:
Synthesis and characterization of new, four-coordinate, high-spin iron(II) and manganese(II) complexes of the general form L2MR2 (L2 = neutral chelating ligand, R = alkyl) are
described. Alkylation of the 
-diimine complex, [ArN=C(Me)-C(Me)=NAr]FeCl2 (Ar = 2,6-diisopropylphenyl), as well as the enantiopure iron dichloride compounds, (-)-(sparteine)FeCl2 and (S)-(tBuBox)FeCl2 ((S)-(tBuBox) = 2,2-bis[2-[4(S)-(R')-1,3-oxazolinyl]propane), with
LiCH2SiMe3 afforded the corresponding dialkyl derivatives. Solution magnetic susceptibility
measurements and X-ray diffraction studies reveal each of the new iron(II) bis-trimethylsilylmethyl complexes to be high-spin, S = 2, tetrahedral molecules. In addition (-)-(sparteine)Fe(CH2CMe3)2, (-)-(sparteine)Fe(CH2C6H5)2, and (S)-(tBuBox)Fe(CH2C6H5)2 were
also prepared and characterized by NMR spectroscopy and elemental analysis. An enantiopure, high-spin, tetrahedral manganese(II) dialkyl complex, (-)-(sparteine)Mn(CH2SiMe3)2,
has also been synthesized. The catalytic activity of the new iron complexes in carbon-carbon
bond forming processes has been evaluated, and stoichiometric reactions of the dialkyls with
olefins, carbon monoxide, and the Lewis acid B(C6F5)3 have been examined.
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