Compounds of the types Pn(pyS)3 (Pn = P, As, Bi; pyS: pyridine-2-thiolate) and Sb(pyS) x Ph3–x (x = 3–1); molecular structures and electronic situations of the Pn atoms
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Compounds of the types Pn(pyS)3 (Pn = P, As, Bi; pyS: pyridine-2-thiolate) and Sb(pyS) x Ph3–x (x = 3–1); molecular structures and electronic situations of the Pn atoms
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<jats:title>Abstract</jats:title>
<jats:p>The compounds <jats:italic>Pn</jats:italic>(pyS)<jats:sub>3</jats:sub> (<jats:italic>Pn</jats:italic> = P, As, Sb, Bi) were synthesized from the respective chloride (<jats:italic>Pn</jats:italic> = P, As, Sb) or nitrate (Bi), pyridine-2-thiol (pySH) and triethylamine (NEt<jats:sub>3</jats:sub>) as a supporting base in THF (P, Sb), CHCl<jats:sub>3</jats:sub> (As) or methanol (Bi). Sb(pyS)<jats:sub>3</jats:sub> was also obtained from the reaction of SbCl<jats:sub>3</jats:sub> with LipyS (prepared <jats:italic>in situ</jats:italic>) in methanol. The compounds Sb(pyS)<jats:sub>2</jats:sub>Ph and Sb(pyS)Ph<jats:sub>2</jats:sub> were prepared in a one-pot reaction starting from SbCl<jats:sub>3</jats:sub> and SbPh<jats:sub>3</jats:sub> (1:1 ratio). Upon Cl/pyS substitution, the resulting reaction mixture allows for a facile separation of the products in hot hexane. P(pyS)<jats:sub>3</jats:sub> and As(pyS)<jats:sub>3</jats:sub> crystallize isostructurally to the reported structure of Sb(pyS)<jats:sub>3</jats:sub> with <jats:italic>κ</jats:italic>-S-bound pyS ligands. These crystal structures feature close <jats:italic>Pn</jats:italic>···<jats:italic>Pn</jats:italic> contacts which are most pronounced for the arsenic derivative. Bi(pyS)<jats:sub>3</jats:sub> adopts a different molecular structure in the solid state, which features two chelating (<jats:italic>κ</jats:italic>
<jats:sup>2</jats:sup>-S,N-pyS) ligands and a <jats:italic>κ</jats:italic>-S-bound ligand. The presence of N→Bi interactions between the nitrogen atom of the <jats:italic>κ</jats:italic>-S-pyS ligand and the Bi atom of another molecule renders this structure a polymer chain along the crystallographic <jats:italic>b</jats:italic> axis with Bi⋅⋅⋅Bi van-der-Waals contacts. The structures of this set of <jats:italic>Pn</jats:italic>(pyS)<jats:sub>3</jats:sub> compounds were also studied in solution using <jats:sup>1</jats:sup>H NMR spectroscopy, revealing equivalent pyS ligands in discrete <jats:italic>Pn</jats:italic>(pyS)<jats:sub>3</jats:sub> molecules. The molecular structure of Sb(pyS)Ph<jats:sub>2</jats:sub> was optimized by quantum chemical methods, and a comparison with the structures reported for the other Sb/pyS/Ph combinations reveals Sb(pyS)<jats:sub>2</jats:sub>Ph to feature the strongest Sb···N interactions with the <jats:italic>κ</jats:italic>-S-pyS ligand. The results of <jats:sup>1</jats:sup>H NMR spectroscopic investigations of the compounds Sb(pyS)<jats:sub>
<jats:italic>x</jats:italic>
</jats:sub>Ph<jats:sub>3–<jats:italic>x</jats:italic>
</jats:sub> (<jats:italic>x</jats:italic> = 3–0) suggest the Ph protons in <jats:italic>ortho</jats:italic> position to be incorporated into intramolecular C–H···S contacts for <jats:italic>x</jats:italic> = 2 and 1. Natural localized molecular orbital (NLMO) calculations were employed in order to gain insights into the electronic situations of the <jats:italic>Pn</jats:italic> atoms and <jats:italic>Pn</jats:italic>–R bonds (R = S, C), especially for the effects caused by formal substitution of <jats:italic>Pn</jats:italic> in the compounds <jats:italic>Pn</jats:italic>(pyS)<jats:sub>3</jats:sub> and the ligand patterns in the compounds Sb(pyS)<jats:sub>
<jats:italic>x</jats:italic>
</jats:sub>Ph<jats:sub>3–<jats:italic>x</jats:italic>
</jats:sub> (<jats:italic>x</jats:italic> = 3–0). For the latter series of compounds, the electronic situation of the Sb atom was further studied by <jats:sup>121</jats:sup>Sb Mössbauer spectroscopy, providing a correlation between the calculated electron density at Sb [<jats:italic>ρ</jats:italic>(0)] and the experimentally observed isomer shift <jats:italic>δ</jats:italic>. The missing link between group 15 and group 13 metal compounds of the type <jats:italic>M</jats:italic>(pyS)<jats:sub>3</jats:sub>, compound Al(pyS)<jats:sub>3</jats:sub>, was synthesized in this work. In the solid state (confirmed crystallographically), the <jats:italic>mer</jats:italic> isomer of this <jats:italic>tris</jats:italic>-chelate complex with distorted octahedral Al coordination sphere was found. This coordination mode was confirmed for the solution state (CDCl<jats:sub>3</jats:sub>) by <jats:sup>1</jats:sup>H and <jats:sup>13</jats:sup>C NMR spectroscopy at <jats:italic>T</jats:italic> = −40 °C.</jats:p>