The structure of liquid methylamine and solutions of lithium in methylamine

The technique of hydrogen/deuterium isotopic substitution in neutron diffra ction has been used to measure the intra- and intermolecular correlations i n liquid methylamine, and 2 and 8 MPM (mole percent metal) lithium methylam ine solutions. We rnd that pure methylamine forms only one strong hydrogen bond per molecule, with evidence for weaker orientations towards the methyl group. As one introduces lithium metal, the intramolecular structure of th e solvent is unaltered. However, intermolecular hydrogen bonding is progres sively disrupted as the concentration of (solvated) cations and excess elec trons increases. Comparison of the total structure factors for 0, 2, 8 and 20 MPM lithium methylamine solutions shows that the greatest shift in the p osition of the principal peak occurs between 8 and 20 MPM. This can be corr elated to the electron delocalization associated with the non-metal-metal t ransition.