Masao Mukaida

One-pot and selective synthesis of a series of [RuCl6−2nLn] (L=bidentate ligand, n=0−3) types of complexes with polypyridyl ligands; another example of the synthetic utility of ‘ruthenium-blue’ solution

Abstract Convenient (one-pot) and selective syntheses of a series of ruthenium complexes with polypyridyl ligands, [RuL3]2+, cis-[RuCl2L2]+ and [RuCl4L]- (L=bpy, phen or Hdpa (di-2,2-dipyridylamine)), including [RuCl6]3−, have been reported as further examples of the synthetic utility of ‘ruthenium-blue’ solution. The methods developed here are also useful for synthesizing selectively such pair complexes as [RuIIICl3(terpy)]-[RuII(terpy)2]2+ and [RuIIICl4py2]−-[RuIICl2py4].

A new synthetic method for ruthenium complexes of β-diketones from ‘ruthenium blue solution’ and their properties

Abstract The ‘ruthenium blue solution’ obtained by reducing hydrated ruthenium(III) trichloride with ethanol was used a convenient starting material in the synthesis of thirteen tris(β-diketonato)ruthenium (III) and six tris(β-diketonato)ruthenate(II) complexes. The procedure of preparing the ‘ruthenium blue solution’ requires no catalyst and is much simpler than the previous methods. A variety of complexes were synthesized in good yields with small changes of the conditions. The Hammett constants of the substituents on the ligand serve as a helpful guide for choosing the operating conditions for the preparation of β-substituted complexes. The yields of the complexes with β-substituted ligands are relatively small, since the presence of a bulky substituent at the β-position decreases the fraction of the enol form of the free ligand. The melting points, magnetic moments, R f values in TLC, UV-Vis, IR, and 1 H NMR spectra were measured. The substituent effects on these properties are discussed.

Synthesis, properties and molecular structure of trans-hydroxobis(2, 2′-bipyridine)nitrosylruthenium(2+): influence of axial ligand on characteristics of nitrosyl moiety in trans-[Ru(NO)XL4]n+ (X=OH, Cl; L=py, 1/2(bpy)) type complexes

Abstract A new complex, trans -[Ru(NO)(OH)(bpy) 2 ] 2+ , was prepared and characterized. The trans form of the complex was confirmed by NMR spectra ( 1 H and 13 C) and X-ray structure determination: P 2 1 / n ; a =16.365(5), b =11.800(7), c =12.169(1) A, β=90.19(7)°; Z =4; D c =1.92, D m =1.92 g cm −3 ; formula weight=659.36; R =0.048 for 4825 observed reflections. Characteristics of the nitrosyl complex were compared with those of the corresponding complex, trans -[Ru(NO)Cl(bpy) 2 ] 2+ , which has a Cl ligand at the trans position of nitrosyl.

Structure of trans-chloronitrosyltetrakis(pyridine)ruthenium(II) bis(hexafluorophosphate) hemihydrate

Abstract The structure of trans-chloronitrosyltetrakis(pyridine)ruthenium(II) bis(hexafluorophosphate) hemihydrate, [RuClpy4NO] (PF6)2·1/2H2O, was determined by X-ray structure analysis. The compound crystallizes in monoclinic form, space group P21/c, with a = 16.0201(12), b = 1.5306(15), c = 27.0912(20) A, β = 91.78(1)°, Z = 8. Least-squares refinement of the structure yielded a final R factor of 0.051 for 4229 independent reflections with |Fo|⩾ 3σ(|Fo|) collected byu a counter method. There are two crystallographically independent formula units in the asymmetric unit. Both have essentially the same structure. The complex cation has a trans octahedral geometry with a nitrosyl and a chloride in the axial position and four pyridines in the equatorial position. The four pyridines form a propeller-like arrangement with an average pitch of about 46°. The RuNO group is approximately linear: the RuNO angle is 174.8(1.9)°, the RuN bond length is 1.760(9) and that of N is 1.132(13) A. The RuCl bond length is 2.314(1) A; this is shortened by the trans-shortening effect of the nitrosyl. The average separation distance of Ru(pyridine) is 2.111(6) A. NMR spectra, along with their temperature dependence, suggests that rapid cogwheel rotation of pyridine rings about RuN(py) axis is occuring in solution.

Synthesis and characterization of polypyridineruthenium(II) complexes containing a linear ambidentate ligand, NCO− or NCS−, and reaction of isocyanato complexes under acidic conditions

Abstract Isocyanato and isothiocyanatopolypyridineruthenium complexes, [Ru(NCX)Y(bpy)(py)2]n+ (bpy=2,2′-bipyridine, py=pyridine; X=O, Y=NO2 for n=0, and Y=py for n=1; X=S, Y=NO2 for n=0, Y=NO for n=2, and Y=py for n=1), were synthesized by the reaction of polypyridineruthenium complexes with potassium cyanate or sodium thiocyanate salt. Isocyanatoruthenium(II) complexes, [Ru(NCO)(NO2)(bpy)(py)2] and [Ru(NCO)(bpy)(py)3]+, react under acidic conditions to form the corresponding ammineruthenium complexes, [Ru(NO)(NH3)(bpy)(py)2]3+. The molecular structures of [Ru(NCO)(bpy)(py)3]ClO4, [Ru(NCS)(NO)(bpy)(py)2](PF6)2 and [Ru(NO)(NH3)(bpy)(py)2](PF6)3 were determined by X-ray crystallography.

Syntheses, characterization, structure and redox behavior of cis-[Ru(NO)X(bpy)(py)2]z (X=monodentate) type complexes of nitrosylruthenium(II) and their related complexes

Abstract Nitrosyl complexes which have both 2,2′-bipyridine and pyridine as co-existing ligands were synthesized and characterized as cis-[Ru(NO)(X)(pby)(py)2]z+ (X=OH, Cl, NO2 for z=2; X=py for z=3). Their characteristics were investigated under the condition of both chemical oxidation and electrochemical reduction. The molecular of cis-[Ru(NO)(OH)(pby)(py)2](PF6)2 was determined: Ru20N5H19O2P2F12,FW=752.40, orthorhombic, a=15.942(2), b=26.541(4), c=12.670(5) A , V=5360(1) A 3 , space group Pbca, Z=8, Dcalc=1.864 g cm−3, Dobs=1.857 g cm−3, μ (Mo Kα)=8.18 cm−1, no. of observations (I>3.00σ(I))=2232, R=0.050, Rw=0.042. The related nitro and oxo complexes which were obtained from the nitrosyl complexes are also reported.

Evidence for a new nitrosyl-to-nitro reaction and an acetamide formation in the {RuNO}6-type complex, cis-[Ru(NO)(CH3CN)(bpy)2]3+

Abstract The reaction between cis-[Ru(NO)(CH3CN)(bpy)2]3+ and a free NO2− gives an appreciable amount of the nitro species cis-[Ru(NO2)(CH3CN)(bpy)2]+. Although definitive evidence for the mechanistic illustration of the nitrosyl-to-nitro conversion is still unavailable, an oxide abstraction from NO2− to the nitrosyl ligand appears to be the key reaction. In addition, cis-[Ru(NO)(CH3C(O)NH)(bpy)2]2+ having an acetamide ligand is formed during the reaction. The structure of the complex, used as a starting material of the present reaction, was determined by single-crystal X-ray diffraction methods; for cis-[Ru(NO)(CH3CN)(bpy)2](ClO4)3·CH3CN: FW=823.91, monoclinic, P21/n, a=12.471(3), b=15.041(7), c=17.598(4) A, β=94.65(2)°, V=3289(1) A3, Z=4, R=0.081, Rw=0.050.

Redox behavior of a binuclear ruthenium complex having a di-μ-nitrosyl ligand, [Ru(acac)22(μ-NO)2] (acac = acetylacetonato)

Abstract The title complex, which has two cis -Ru(acac) 2 fragments connected doubly by μ-N (O) bridges, undergoes both a one-electron reversible and a second one-electron irreversible reduction, in addition to a one-step, two-electron irreversible oxidation. In the oxidation process, the binuclear structure is disintegrated to give two moles of cis -[Ru(NO)(CH 3 CN)(acac) 2 ] + from one mole of the title complex.

Electrochemical behavior of the oxo complex of Ru(IV), trans-[RuCl(O)(py)4]+, in both non-aqueous and aqueous solvents

Abstract The electrochemical behavior of trans -[Ru IV Cl(O)(py) 4 ] + , and that of its related complexes, trans -[Ru III Cl(OH)(py) 4 ] + and trans -[Ru II Cl(H 2 O)(py) 4 ] + , were investigated in both acetonitrile and aqueous solvents. The reduction process of trans -[Ru IV Cl(O)(py) 4 ] + was an irreversible one; it converted into trans -[Ru II Cl(OH)(py) 4 ] 0 in CH 3 CN and trans -[Ru II Cl(H 2 O)(py) 4 ] + in aqueous solvent by a one-step two-electron reduction. The oxo complex undergoes a one-electron oxidation to give a reactive trans -[Ru V Cl(O)(py) 4 ] 2+ , which is the species capable of oxidizing organic substances.

One-electron oxidation behavior of {MNO}6-type nitrosyl complexes having acetylacetonato ligand, [M(NO)Cl5−2n(acac)n]m (M=Ru, Os; n=1, 2; acac=acetylacetonato)

Abstract The electrochemical behavior of several complexes with the general formula [M(NO)Cl 5−2 n (acac) n ] m (M=Ru, Os; n =1, 2; acac=acetylacetonato) was investigated: mer -[Ru(NO)Cl 3 (acac)] − ( 1 , n =1), cis -[Ru(NO)Cl(acac) 2 ] ( 2 , n =2), mer -[Os(NO)Cl 3 (acac)] − ( 3 , n =1), cis -[Os(NO)Cl(acac) 2 ] ( 4 , n =2). The study includes the known corresponding n =0 complexes, [M(NO)Cl 5 ] 2− (M=Ru, Os), for comparison. All these complexes undergo a one-electron oxidation, which is rather unusual redox behavior in the {MNO} 6 -type nitrosyl complexes. The behavior of some of these complexes as electrophiles was also described. Molecular structures with a meridional configuration were established for the n =1 complexes ([Ru(NO)Cl 3 (acac)] − ( 1 ) and [Os(NO)Cl 3 (acac)] − ( 3 )) by X-ray structure determinations. Crystal data for 1 (Bu 4 N salt): C 21 H 43 N 2 O 3 Cl 3 Ru, a =31.443(9), b =21.86(1), c =19.852(6) A, β =119.65(2)°, monoclinic, C 2/ c , Z =16. Crystal data for 3 (Cs salt): C 5 H 7 NO 3 Cl 3 OsCs, a =7.942(1), b =12.602(2), c =7.451(2) A, α =105.91(2), β =98.20(2), γ =90.31(1)°, triclinic, P 1 , Z =2.