Wai-Man Cheung

Ruthenium complexes with tetraphenylimidodiphosphinate: Syntheses, structures, and applications to catalytic organic oxidation

Treatment of Ru(PPh3)3Cl2 with K(tpip) (tpip(-)=[N(Ph2PO)2](-)) afforded Ru(tpip)(PPh3)2Cl (1), which reacted with 4- t-Bu-C6H4CN, SO2(g), and NH 3(g) to give Ru(tpip)(PPh3)2Cl(4- t-BuC6H4CN) (2), Ru(tpip)(PPh3)2Cl(SO2) (3), and fac-[Ru(NH3)3(PPh3)2Cl][tpip] (4), respectively. Reaction of [Ru(CO)2Cl2] x with K(tpip) in refluxing tetrahydrofuran (THF) led to isolation of the K/Ru bimetallic compound K 2Ru2(tpip)4(CO)4Cl2 (5). Photolysis of cis-Ru(tpip) 2(NO)Cl in MeCN and wet CH 2Cl 2 afforded cis-Ru(tpip) 2(MeCN)Cl ( 6) and cis-Ru(tpip)2(H2O)Cl (7), respectively. Refluxing 6 in neat THF yielded Ru(tpip) 2(THF)Cl (8). Treatment of Ru(CHR)Cl2(PCy3)2 (Cy=cyclohexyl) with [Ag(tpip)] 4 afforded cis-Ru(tpip)2(CHR)(PCy3) [R=Ph (9), OEt (10)]. Complex 9 is capable of catalyzing oxidation of alcohols and olefins with N-methylmorpholine N-oxide and iodosylbenzene, respectively. The crystal structures of 2-7 and 9 were determined.

Dinuclear ruthenium nitrido complexes supported by an oxygen tripodal ligand.

Dinuclear ruthenium nitrido complexes supported by the Kläuis tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized starting from the ruthenium(VI) nitrido precursor [L(OEt)Ru(VI)(N)Cl(2)] (1). Heating a solution of 1 in CCl(4) at reflux, followed by recrystallization from hexane under nitrogen, afforded the mixed-valence ruthenium(V)-ruthenium(IV) μ-nitrido complex [L(OEt)Cl(2)Ru(V)(μ-N)Ru(IV)Cl(2)L(OEt)] (2). The cyclic voltammogram of 2 exhibited reversible couples at 0.19 and 1.13 V versus Cp(2)Fe(+/0), which are assigned as the Ru(V)-Ru(IV)/Ru(IV)-Ru(IV) and Ru(V)-Ru(V)/Ru(V)-Ru(IV) couples, respectively. Recrystallization of 2 from Et(2)O/heptane in air yielded the diamagnetic Ru(IV)-Ru(IV) complex [H(13)O(6)][{L(OEt)Ru(IV)Cl(2)}(2)(μ-N)] ([H(13)O(6)][2]), which underwent cation exchange with n-Bu(4)NOH to give [n-Bu(4)N][2]. X-ray diffraction revealed that the complex anions in [H(13)O(6)][2] and [n-Bu(4)N][2] contain linear, symmetric Ru-N-Ru bridges. Treatment of 1 with [(η(6)-p-cymene)Ru(II)Cl(2)](2) in benzene afforded the tetranuclear ruthenium(IV) complex [L(OEt)Cl(2)Ru(IV)(μ-N)Ru(IV)(H(2)O)Cl(2)](2) (3) containing symmetric Ru(IV)-N-Ru(IV) bridges. The reaction of 1 with [Ru(II)(H)(Cl)(CO)(PCy(3))(2)] (Cy = cyclohexyl) gave the ruthenium(VI)-ruthenium(II) nitrido complex [L(OEt)Cl(2)Ru(VI)(μ-N)Ru(II)(H)Cl(CO)(PCy(3))(2)] (4). The observed short Ru(II)-N bond distance [1.915(5) Å] and high C-O stretching frequency (1985 cm(-1)) in 4 are suggestive of π interaction between Ru(II) and the nitride.

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

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.