The synthesis of a series of dinuclear Ru(IV) µ-oxo complexes [Ru(P0r)(OR)]2O and [Ru(Por)X]2O (Por = OEP, TPP, T-n-PrP; OR = OCH3, OC2H5, p-OC6H4CH3, o-OC6H4OH; X = Br, Cl, CF3C02, HSO4) by tert-butyl hydroperoxide oxidation of Ru(Por)(CO)(R OH) (R = CH3, C2H5) is described. An X-ray crystal structure determination of [Ru- (TPP)(p-OC6H4CH3)]2O was carried out. The complex crystallizes in the triclinic space group Ci1-P3# with two molecules in a unit cell of dimensions a = 16.911 (11) Å, b = 10.802 (12) Å, c = 12.979 (8) Å, α; = 99.96 (3)°,β = 104.31 (2)°, and γ = 77.32 (2)°. Least-squares refinement has led to a final value of the conventional R index (on F2) of 0.177 based on 7630 independent reflections. The Ru-O(Ru) and Ru-0(p-0C6H4CH3) bond lengths are 1.789 (11) and 1.964 (11) Å, respectively, and the Ru-O-Ru angle is 177.8 (7)°. The Ru(IV) µ-oxo complexes can be reduced by NaBH4or PPh3to form the Ru(II) species Ru(Por)L2. Ru(TPP)(EtOH)2in noncoordinating solvents is oxidized by O2to [Ru(TPP)(OEt)]2O, but in the presence of excess ethanol the oxidation halts at a Ru(III) species, Ru(TPP)(OEt)(EtOH)·2EtOH. In noncoordinating solvents this complex is further oxidized by O2to the Ru(IV) µ-oxo ethoxide complex. The Ru(III) complex was characterized by an X-ray crystal structure analysis. The complex crystallizes in the triclinic space group Ci1-P with unit cell parameters a = 9.894 (4) Å, b = 12.946 (6) Å, c = 9.758 (5) Å, α = 112.06 (2)°, β = 94.12 (2)°, γ = 71.85 (2)°, and one molecule per unit cell. Least-squares refinement based on 5073 unique reflections led to a final R index (on F2) of 0.106. The centrosymmetric complex exhibits one Ru-O bond length of 2.019 (3) Å. These results demonstrate the solvent dependence of the interactions of oxygen with ruthenium porphyrins. The Ru(III) complex reported herein is the first to be structurally characterized.
ASJC Scopus subject areas
- Colloid and Surface Chemistry