Helen R L Barley

Publications (3)23.88 Total impact

• Article: Alkali-metal-mediated zincation of ferrocene: synthesis, structure, and reactivity of a lithium tmp/zincate reagent.

  Helen R L Barley, William Clegg, Sophie H Dale, Eva Hevia, Gordon W Honeyman, Alan R Kennedy, Robert E Mulvey
  Angewandte Chemie International Edition 10/2005; 44(37):6018-21. · 13.45 Impact Factor
• Article: A mixed iron(III)/lithium alkoxide.

  Helen R L Barley, Alan R Kennedy, Robert E Mulvey
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  ABSTRACT: The heterometallic alkoxide catena-poly[[tetra-mu2-tert-butoxo-1:2kappa4O:O;1:3kappa4O:O-bis(tetrahydrofuran)-2kappaO,3kappaO-iron(III)dilithium(I)]-mu-bromo], [FeLi2Br(C4H9O)4(C4H8O)2]n, forms a one-dimensional chain through an a-glide. This conformation is achieved through the formation of Fe(III)/O/Li/O rings and Li-Br-Li bridges.
  Acta Crystallographica Section C Crystal Structure Communications 08/2005; 61(Pt 7):m346-7. · 0.52 Impact Factor
• Article: Sodium dialkyl-amidozincates: alkyl or amido bases? An experimental and theoretical case study.

  Prokopis C Andrikopoulos, David R Armstrong, Helen R L Barley, William Clegg, Sophie H Dale, Eva Hevia, Gordon W Honeyman, Alan R Kennedy, Robert E Mulvey
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  ABSTRACT: Alkali metal zincate reagents are attracting considerable attention at present in respect to their often special reactivity/selectivity in hydrogen-metal and halogen-metal interconversion reactions. Heteroleptic diorgano-amidozincates, typified by lithium di-tert-butyltetramethylpiperidinozincate, have proved to be especially useful reagents in such applications. In this paper the related sodium TMP-zincate, prepared as its TMEDA (N,N,N',N'-tetramethylethylenediamine) adduct, [TMEDA.Na(mu-tBu)(mu-TMP)Zn(tBu)], 1, is introduced. This new zincate was synthesized from a 1:1:1 mixture of tBu2Zn, NaTMP, and TMEDA in hexane solution, as a colorless crystalline solid in an isolated yield of 58%. It has been characterized in solution by 1H and 13C NMR spectroscopic studies. An X-ray crystallographic study reveals that 1 adopts a five-membered (NaNZnCC) ring system featuring a TMP bridge and an unusual, asymmetrical tBu bridge involving a Na...Me agostic contact. Probing the basicity of 1, reaction with benzene affords the new hetero(tri)leptic zincate [TMEDA.Na(mu-Ph)(mu-TMP)Zn(tBu)], 2, which has also been crystallographically characterized. Thus, in this hydrogen-metal exchange reaction 1 functions as an alkyl base, with the elimination of butane, as opposed to an amido base. Also reported are DFT calculations using B3LYP functionals and the 6-311G** basis set on model zincate systems, which intimate that the preference of 1 for tBu ligand transfer over TMP ligand transfer in the reaction toward benzene is due to favorable thermodynamic factors.
  Journal of the American Chemical Society 06/2005; 127(17):6184-5. · 9.91 Impact Factor