A Nitrido-bridged Heterometallic Ruthenium(IV)/Iron(IV) Phthalocyanine Complex Supported by A Tripodal Oxygen Ligand, [Co(η-CH){P(O)(OEt)}]: Synthesis, Structure, and Its Oxidation to Give Phthalocyanine Cation Radical and Hydroxyphthalocyanine Complexes.

Dinuclear iron nitrido phthalocyanine complexes are of interest owing to their applications in catalytic oxidation of hydrocarbons. While nitrido-bridged diiron phthalocyanine complexes are well documented, the oxidation chemistry of heterodinuclear iron(IV) phthalocyanine nitrides has not been well explored. In this paper we report on the synthesis of a heterometallic Fe/Ru phthalocyanine nitride and its oxidation to yield phthalocyanine cation radical and hydroxyphthalocyanine complexes. Treatment of [Fe(Pc)] (Pc = phthalocyanine dianion) with [Ru(L)(N)Cl] (L = [Co(η-CH){P(O)(OEt)}]) (1) afforded the heterometallic μ-nitrido complex [Cl(L)Ru(μ-N)Fe(Pc)(HO)] (2) that contains an Ru=N = Fe linkage with the Ru-N and Fe-N distances of 1.689(6) and 1.677(6) Å, respectively, and Ru-N-Fe angle of 176.0(4)°. Substitution of 2 with 4- tert-butylpyridine (Bupy) gave [Cl(L)Ru(μ-N)Fe(Pc)(Bupy)]. The cyclic voltammogram of 2 displayed a reversible Pc-centered oxidation couple at +0.18 V versus Fc (Fc = ferrocene). The oxidation of 2 with [N(4-BrCH)]SbCl led to isolation of the cationic complex [Cl(L)Ru(μ-N)Fe(Pc)(HO)][SbCl][SbCl(OH)] (2[SbCl][SbCl(OH)]), whereas that with PhICl yielded the chloride complex [Cl(L)Ru(μ-N)Fe(Pc)Cl] (3). Complexes 2[SbCl][SbCl(OH)] and 3 have been characterized by X-ray crystallography. The UV/visible spectra of 2 (λ = 515 and 747 nm) and 3 (λ = 506 and 748 nm) displayed absorption bands that are characteristic of Pc cation radical. The EPR spectrum of 3 showed a signal with the g value of 2.0012 (width = 5 G) that is consistent with an organic radical. The spectroscopic data support the formulation of 2 and 3 as Ru-Fe Pc cation radical complexes. The reaction of 2 with PhI(CFCO) in dried CHCl afforded a mixture of [Cl(L)Ru(μ-N)Fe(Pc)(CFCO)] (4) and a hydroxyphthalocyanine complex, [Cl(L)Ru(μ-N)Fe(Pc-OH)(HO)](CFCO) (5), whereas that in wet CHCl (containing ca. 0.5% water) led to isolation of 5 as the sole product. Complex 4 was independently prepared by salt metathesis of 3 with AgCFCO.