Notes. High-valent ruthenium oxo complexes of NNN′N′-tetramethyl-3,6-dimethyl-3,6-diazaoctane-1,8-diamine (L1). X-ray crystal structure determination of cis-[RuIII(L1)Cl2]ClO4

Abstract

The reaction of K2[RuCl5(H2O)] with NNN′N′-tetramethyl-3,6-dimethyl-3,6-diazaoctane-1,8-diamine (L1) in ethanol yielded cis-[RuIII(L1)Cl2]+, which was isolated as the ClO4 - salt. The optical spectrum of cis-[RuIII(L1)Cl2]ClO4 in acetonitrile displays one intense band at 375 nm attributed to a pπ(Cl) → dπ* (Ru) transition. cis.-[RuIII(L1)Cl2]ClO4 has been characterized by X-ray crystallography: space group P21/c, a = 11.716(5), b = 13.089(4), c = 12.981(5) Å, β = 94.28(2)°, Z = 4, and R = 0.076 for 1 913 observed Mo-Kα data. The co-ordination geometry around the metal ion is distorted octahedral with cis arrangement of the two chloride ligands. The average Ru-N and Ru-Cl bond distances are 2.17(1) and 2.345(4) Å, respectively. Treatment of cis-[RuIII(L1)Cl2]ClO4 with silver(I) p-toluenesulphonate in hot water and then H2O2 gave [RuVI(L1)(O)2]2+ isolated as the ClO4 - salt. [RuVI(L1)(O)2][ClO4]2 is diamagnetic (μeff. = 0) and has an intense i.r. band at ca. 850 cm-1 attributed to νasym (Ru=O) stretching. The E1/2 value of the [RuVI(L1)(O)2]2+/[Ru IV(L1)(O)(H2O)]2+ couple in 0.1 mol dm-3 CF3CO2H is 0.79. V vs. a saturated calomel electrode. The reaction of [RuIV(L1)(O)2][ClO4]2 with styrene produced benzaldehyde.