Ralf Haiges - Why Are [P(C6H5)4]+N3- and [As(C6H5)4]+N3- Ionic Salts and Sb(C6H5)4N3 and Bi(C6H5)4N3 Covalent Solids? A Theoretical Study Provides an Unexpected Answer.

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      Publication Details (including relevant citation   information): Christe, Karl O., Haiges, Ralf, Boatz,   Jerry A., Brooke Jenkins, H. Donald, Garner, Edward B., Dixon,   David A., Inorg. Chem., 2011,   50 (8), pp 3752-3756

      Abstract: A recent crystallog. study has shown   that, in the solid state, P(C6H5)4N3 and As(C6H5)4N3 have ionic   [M(C6H5)4]+N3--type structures, whereas Sb(C6H5)4N3 exists as a   pentacoordinated covalent solid. Using the results from d.   functional theory, lattice energy (VBT) calcns., sublimation   energy ests., and Born-Fajans-Haber cycles, it is shown that the   max. coordination nos. of the central atom M, the lattice   energies of the ionic solids, and the sublimation energies of the   covalent solids have no or little influence on the nature of the   solids. Unexpectedly, the main factor detg. whether the covalent   or ionic structures are energetically favored is the first   ionization potential of [M(C6H5)4]. The calcns. show that at   ambient temp. the ionic structure is favored for P(C6H5)4N3 and   the covalent structures are favored for Sb(C6H5)4N3 and   Bi(C6H5)4N3, while As(C6H5)4N3 presents a borderline case. [on   SciFinder(R)]

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