Synthesis,Structures and Reactivity of Lanthanoid(II) Formamidinates of Varying Steric Bulk |
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| Authors: | Prof. Dr. Marcus L. Cole Prof. Dr. Glen B. Deacon Dr. Craig M. Forsyth Prof. Dr. Peter C. Junk Dr. Kristina Konstas Dr. Jun Wang Henry Bittig Daniel Werner |
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| Affiliation: | 1. School of Chemistry, Monash University, Victoria 3800 (Australia);2. Present address: School of Chemistry, University of New South Wales, Sydney, NSW, 2052 (Australia);3. School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Qld, 4811 (Australia);4. Present address: CSIRO Division of Material Science and Engineering, Clayton, VIC, 3168 (Australia) |
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| Abstract: | New reactive, divalent lanthanoid formamidinates [Yb(Form)2(thf)2] (Form=[RNCHNR]; R=o‐MeC6H4 (o‐TolForm; 1 ), 2,6‐Me2C6H3 (XylForm; 2 ), 2,4,6‐Me3C6H2 (MesForm; 3 ), 2,6‐Et2C6H3 (EtForm; 4 ), o‐PhC6H4 (o‐PhPhForm; 5 ), 2,6‐iPr2C6H3 (DippForm; 6 ), o‐HC6F4 (TFForm; 7 )) and [Eu(DippForm)2(thf)2] ( 8 ) have been prepared by redox transmetallation/protolysis reactions between an excess of a lanthanoid metal, Hg(C6F5)2 and the corresponding formamidine (HForm). X‐ray crystal structures of 2 – 6 and 8 show them to be monomeric with six‐coordinate lanthanoid atoms, chelating N,N′‐Form ligands and cis‐thf donors. However, [Yb(TFForm)2(thf)2] ( 7 ) crystallizes from THF as [Yb(TFForm)2(thf)3] ( 7 a ), in which ytterbium is seven coordinate and the thf ligands are “pseudo‐meridional”. Representative complexes undergo C? X (X=F, Cl, Br) activation reactions with perfluorodecalin, hexachloroethane or 1,2‐dichloroethane, and 1‐bromo‐2,3,4,5‐tetrafluorobenzene, giving [Yb(EtForm)2F]2 ( 9) , [Yb(o‐PhPhForm)2F]2 ( 10) , [Yb(o‐PhPhForm)2Cl(thf)2] ( 11) , [Yb(DippForm)2Cl(thf)] ( 12) and [Yb(DippForm)2Br(thf)] ( 16) . X‐ray crystallography has shown 9 to be a six‐coordinate, fluoride‐bridged dimer, 12 and 16 to be six‐coordinate monomers with the halide and thf ligands cis to each other, and 11 to have a seven‐coordinate Yb atom with “pseudo‐meridional” unidentate ligands and thf donors cis to each other. The analogous terbium compound [Tb(DippForm)2Cl(thf)2] ( 13 ), prepared by metathesis, has a similar structure to 11 . C? Br activation also accompanies the redox transmetallation/protolysis reactions between La, Nd or Yb metals, Hg(2‐BrC6F4)2, and HDippForm, yielding [Ln(DippForm)2Br(thf)] complexes (Ln=La ( 14 ), Nd ( 15 ), Yb ( 16 )). |
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| Keywords: | C?F/Cl/Br activation formamidinate heteroleptic lanthanide compounds lanthanides X‐ray diffraction |
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