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Synthesis and molecular structure of the polar, binuclear complex, monochlorotetra-(6-fluoro-2-oxopyridine)diruthenium(II,III)

1986; Elsevier BV; Volume: 5; Issue: 11 Linguagem: Inglês

10.1016/s0277-5387(00)84862-7

1873-3719

Akhil R. Chakravarty, F. Albert Cotton, Willi Schwotzer,

Ferrocene Chemistry and Applications

The dark purple title compound was prepared by reaction of Ru2Cl(O2CCH3)4 with molten 6-fluoro-2-hydroxypyrine (Hfhp) in quantitative yield. Crystals of composition Ru2Cl(fhp)4 were obtained by slow diffusion of hexane into a CH2Cl2 solution of the compound. The crystals belong to the tetragonal space group I4mm with the following unit-cell dimensions: a = b = 10.890(2) Å, c = 13.178(4) Å, α = β = γ = 90.0°, V = 1562.8(6) Å3, and Z = 2. The Ru2Cl(fhp)4 molecule, which has crystallographic 4mm (C4c) symmetry, contains a diruthenium(II,III) unit with a metalmetal bond order of 2.5. The four bridging fhp ligands across the Ru2 unit are oriented in one direction to form a polar molecule. The coordinatioin spheres of the two ruthenium atoms [Ru(1) and Ru(2)] are Ru(2)N(I)4 and Ru(1)Cl(1)O(1)4, respectively. The axial site on Ru(1) is blocked by four F(1) atoms. The Ru(1)Ru(2), Ru(2)Cl(1), Ru(2)O(1) and Ru(1)N(1) distances are 2.284(1), 2.427(3), 1.971(2) and 2.089(4) Å, respectively. The electronic spectrum of the compound in CH2Cl2 shows two strong bands at 552 nm (ε = 4720 M−1 cm−1) and 355 nm ε = 3770 M−1 cm−1). Cyclic voltammetry of Ru2Cl(fhp)4 in CH2Cl2 in the presence of 0.1 M [N(C2H5)4]ClO4 at 100 mV s−1 shows two quasireversible metal-centered one-electron oxication and reduction processes at +1.68 (ΔEp = 120 mV) and −0.01 V (ΔEp = 126 mV), respectively, vs an AgAgCl reference electrode.