Metalloidalmethyl substituent effects by 13C and 19F NMR : electron release in the neutral ground state. |
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| Authors: | W Adcock DP Cox W Kitching |
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| Institution: | School of Physical Sciences, The Flinders University of South Australia, Bedford Park, S.A. 5042. Australia;Department of Chemistry, University of Queensland, Brisbane, Queensland, Australia |
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| Abstract: | 13C and 19F chemical shift studies of a series of CH2M(CH3)3 and CH2M(C6H5)3 (M Si, Ge, Sn, Pb) - substituted aryl derivatives (phenyl; 1-naphthyl; 2-naphthyl) have established unambiguously that the order of hyperconjugative electron release in the neutral ground state is Pb>Sn>Ge>Si. This order is clearly at variance with the commonly accepted order(Pb>Sn>Ge>Si) based on studies of electron deficient substrates. The phenomenon is discussed in terms of current theories on σ-π interactions. In addition, substituent parameters (σI and σRo) for the PB(CH3)3 group have been derived utilizing new data from the fluorophenyl tag. These new constants are compared with those previously reported. |
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| Keywords: | Address correspondence to this author |
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