Thionitrosylkomplexe des Rutheniums. Die Kristallstruktur von (PPh4)2[{RuBr4(NS)}2(μ-N2S2)]

Thionitrosyl Complexes of Ruthenium. Crystal Structure of (PPh₄)₂[{RuBr₄(NS)}₂ (μ-N₂S₂)] Ruthenium trichloride reacts with trithiazyl chloride, yielding cis-RuCl₄ (NS)₂. With triphenylmethylphosphonium chloride this forms the complex [RuCl₄(NS)₂Cl]^? in which a chloride ion is bonded between the sulfur atoms in a chelate manner. With tetraphenylphosphonium bromide, RuCl₄(NS)₂ undergoes a redox reaction that affords (PPh₄)₂[{RuCl₄(NS)}₂(μ-N₂S₂)] which can be transformed to the title compound by the action of trimethylsilyl bromide. The i.r. spectra are reported. The crystal structure of (PPh₄)₂[{RuBr₄(NS)}₂(μ-N₂S₂)] · 4 CH₂X₂ (X ? Cl, Br) was determined with X-ray diffraction data (1534 observed reflexions, R = 0.085). Crystal data: monoclinic, space group P2₁/n, Z = 2, a = 1680.7, b = 1287.0, c = 1706.1 pm and β = 99.97°. The compound consists of tetraphenylphosphonium cations, CH₂Br₂ and CH₂Cl₂ molecules (statistically) and centrosymmetric anions [{RuBr₄(NS)}₂(μ-N₂S₂)]^2? in which the ruthenium atoms are linked via the nitrogen atoms of a planar N₂S₂ ring. In the corresponding trans-positions every Ru atom has a thionitrosyl ligand with a nearly arrangement Ru?N?S with RuN and NS bond lengths of 169 und 151 pm, respectively. Four bromine atoms complete the distorted octahedral coordination of each ruthenium atom. The bromine atoms that are coplanar with the N₂S₂ ring form rather short Br…?S contacts with a mean distance of 317 pm.