Benzeneselenolates of Mercury(II). Crystal and Molecular Structures of [Hg(SePh)2] and (nBu4N)[Hg(SePh)3]

The reaction of dibenzenediselenide, (SePh)2, with mercury in refluxing xylene gives bis(benzeneselenolato)mercury(II), [Hg(SePh)2], in a good yield. (nBu4N)[Hg(SePh)3] is obtained by the reaction of [Hg(SePh)2] with a solution of [SePh]- and (nBu4N)Br in ethanol. The solid state structures of both compounds have been determined by X-ray diffraction.
The mercury atom in [Hg(SePh)2] (space group C2, a = 7.428(2), b = 5.670(1), c = 14.796(4) Å, b = 103.61(1)°) is linearly co-ordinated by two selenium atoms (Hg-Se = 2.471(2) Å, Se-Hg-Se = 178.0(3)°). Additional weak interactions between the metal and selenium atoms of neighbouring molecules (Hg···Se = 3.4 - 3.6 Å) associate the [Hg(SePh)2] units to layers.
The crystal structure of (nBu4N)[Hg(SePh)3] (space group P21/c, a = 9.741(1), b = 17.334(1), c = 21.785(11) Å, b = 95.27(5)°) consists of discrete complex anions and (nBu4N)+ counter ions. The coordination geometry of mercury is distorted trigonal-planar with Hg-Se distances ranging between 2.5 and 2.6 Å.