A new diruthenium(II,III) compound, Ru2(CCPh)(PhNpy)4·2CH2Cl2, with an axial η1-acetylide ligand

Chakravarty, Akhil R. ; Albert Cotton, F. (1986) A new diruthenium(II,III) compound, Ru2(CCPh)(PhNpy)4·2CH2Cl2, with an axial η1-acetylide ligand Inorganica Chimica Acta, 113 (1). pp. 19-26. ISSN 0020-1693

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Official URL: http://dx.doi.org//10.1016/S0020-1693(00)86851-6

Related URL: http://dx.doi.org/10.1016/S0020-1693(00)86851-6


The compound Ru2(CCPh)(PhNpy)4 was prepared by reacting Ru2Cl(PhNpy)4 and Li(CCPh) in a toluene-tetrahydrofuran mixture. The product, which was purified by column chromatography on a neutral alumina column using benzene as an eluting agent, was obtained in ca. 70% yield. Crystals of composition Ru2(CCPh)(PhNpy)4·2CH2Cl2 (1), obtained from a CH2Cl2-hexane mixture (1:1 V/V) at -20 °C, belong to the triclinic system, space group P 1, with unit cell dimensions of a = 13.857(6), b = 19.338(9), c = 10.463(4) Å, α = 104.03(4)°, β = 108.25(4)°, γ = 93.55(4)°, V = 2554(2) Å3, Z = 2. The structure was refined to R = 0.064 (Rw = 0.073). The complex has a diruthenium(II,III) unit bridged by four PhNpy- ligands, all oriented in the same direction. The axial ligand on the ruthenium is an η1acetylide, CCPh. The Ru(1)-Ru(2) distance in 1 is 2.319(2) Å. The Ru(1)-C(1) and average Ru---N distances are 2.08(3) and 2.07[2] Å, respectively. The C(1)-C(2) distance is 1.14(3) A and the Ru(2)- Ru(1)-C(1) group is essentially linear. The Ru(1)- C(1)-C(2) and C(1)-C(2)-C(3) angles are 172(3) and 173(3)°, respectively. The complex is paramagnetic, exhibiting a moment of 3.92 μB (308 K). The Ru---Ru bond order is 2,5 with a σ24δ2- (δ∏)3 ground electronic configuration. The electronic spectrum of the compound in CH2 Cl2 displays two absorption bands in the visible region, viz., at 735 nm (ε = 1050 M-1 cm-1) and at 480 nm (ε = 1630 M-1 cm-1). Cyclic voltammetry in CH2Cl2 in the presence of 0.1 M (TBA)PF6 at 100 mV s-1 shows nearly reversible metal-centered one-electron oxidation and reduction processes at +0.235 V (δEp = 70 mV) and -0.985 V (δEp = 70 mV), respectively, vs. an Ag---AgCl reference electróde. A quasireversible oxidation at +1.050 V is also observed.

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