A Nitrido-bridged Heterometallic Ruthenium(IV)/Iron(IV) Phthalocyanine Complex Supported by A Tripodal Oxygen Ligand, [Co(η5‑C5H5){P(O)(OEt)2}3]−: Synthesis, Structure, and Its Oxidation to Give Phthalocyanine Cation Radical and Hydroxyphthalocyanine Complexes

• Published in: Inorganic chemistry 2018-08, Vol.57 (15), p.9215-9222
• Main Authors: Cheung, Wai-Man, Ng, Wai-Ming, Wong, Wai-Ho, Lee, Hung Kay, Sung, Herman H.-Y, Williams, Ian D, Leung, Wa-Hung
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.8b01229

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 FeIV/RuIV phthalocyanine nitride and its oxidation to yield phthalocyanine cation radical and hydroxyphthalocyanine complexes. Treatment of [FeII(Pc)] (Pc2– = phthalocyanine dianion) with [RuVI(LOEt)­(N)­Cl2] (LOEt – = [Co­(η5-C5H5)­{P­(O)­(OEt)2}3]−) (1) afforded the heterometallic μ-nitrido complex [Cl2(LOEt)­RuIV(μ-N)­FeIV(Pc)­(H2O)] (2) that contains an RuIV=N = FeIV 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 [Cl2(LOEt)­RuIV(μ-N)­FeIV(Pc)­(Bupy)]. The cyclic voltammogram of 2 displayed a reversible Pc-centered oxidation couple at +0.18 V versus Fc+/0 (Fc = ferrocene). The oxidation of 2 with [N­(4-BrC6H4)3]­SbCl6 led to isolation of the cationic complex [Cl2(LOEt)­RuIV(μ-N)­FeIV(Pc·+)­(H2O)]­[SbCl6]0.85[SbCl5(OH)]0.15 (2[SbCl6]0.85[SbCl5(OH)]0.15), whereas that with PhICl2 yielded the chloride complex [Cl2(LOEt)­RuIV(μ-N)­FeIV(Pc·+)­Cl] (3). Complexes 2[SbCl6]0.85[SbCl5(OH)]0.15 and 3 have been characterized by X-ray crystallography. The UV/visible spectra of 2 + (λmax = 515 and 747 nm) and 3 (λmax = 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 RuIV–FeIV Pc cation radical complexes. The reaction of 2 with PhI­(CF3CO2)2 in dried CH2Cl2 afforded a mixture of [Cl2(LOEt)­RuIV(μ-N)­FeIV(Pc·+)­(CF3CO2)] (4) and a hydroxyphthalocyanine complex, [Cl2(LOEt)­RuIV(μ-N)­FeIV(Pc–OH)­(H2O)]­(CF3CO2) (5), whereas that in wet CH2Cl2 (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 AgCF3CO2.