Structural studies of steric effects in phosphine complexes. Part VII. Synthesis, crystal and molecular structure of the chloroperchloratotri(o-tolyl)phosphinemercury(II) dimer

Abstract

The synthesis and crystal and molecular structure of the chloroperchloratotri(o-tolyl)phosphinemercury(II) dimer are reported. The compound [HgP(o-tolyl)₃ClClO₄]₂ belongs to the orthorhombic space group Pbca [Formula: see text] with a = 12.218(2), b = 13.814(2), c = 26.074(3) Å, and Z = 4. The structure was refined to a final R of 0.046 for 2584 reflections measured by diffractometer. The crystal structure consists of discrete centrosymmetric dimeric molecules of [HgP(o-tolyl)₃ClClO₄]₂ separated by normal van der Waals distances. The unique mercury atom forms two strong bonds (Hg—P 2.395(3), Hg—Cl(1) 2.332(4) Å) which deviate from linearity (P—Hg—Cl 164.1(1)°) and two weak bonds (Hg—O(1) 2.73(2) to the perchlorato group, Hg—Cl(1 *) 3.109(4) Å linking the mercury atoms about centers of symmetry). The four-fold coordination geometry about each mercury can be described as trigonal bipyramidal with the phosphorus and Cl(1) axial, and one equatorial site unoccupied. Intramolecular interactions are discussed with the assistance of cone angle calculations and a ligand profile for P(o-tolyl)₃ (θ = 198°). Vibrational and ³¹P nmr spectra data are also presented for [HgP(o-tolyl)₃ClClO₄]₂.