Synthesis,X—Ray Structure and Characterization of a Triruthenium Cluster Complex Ru^Ⅲ3（μ3—O）（μ—CH3COO）6（py）2Cl with Four Steps One—electron Redox Processes

The synthesis and crystal structure of oxo-centered carboxylate-bridge trinuclear ruthenium complex,Ru3O(CH3OO)6(py)2Cl(py=pyridine)(1),are reported herein.The complex 1 has been characterized by IR,cyclic voltammetry (CV),UV-Vis and X-ray crystal analysis.The complex 1 in 0.1 mol/L (n-C4H9)4HPF6-CH2Cl2 solution at room temperature shows four oneelectron redox processes at E1/2=-1.38,1.20,-0.17 and 1.07V vs. Ag/AgCl.     

Effect of Mn（Ⅱ） and Ce（Ⅳ） Ions on the Oxidation of Lactic Acid by Chromic Acid

The kinetics and mechanism of lactic acid oxidation in the presence of Mn（Ⅱ） and Ce（Ⅳ） ions by chromic acid were studied spectrophotometrically. The oxidation of lactic acid by Cr（Ⅵ） was found to proceed in two measurable steps, both of which gave pyruvic acid as the primary product in the absence of Mn（Ⅱ）.2Cr（Ⅵ）＋2CH3CHOHCOOH→2CH3COCOOH＋Cr（Ⅴ）＋C（Ⅲ） Cr（V）＋CH3CHOHCOOH→Cr（Ⅲ）＋CH3COCOOHThe observed kinetics was explained due to the catalytic and inhibitory effects of Mn（Ⅱ） and Ce（Ⅳ） on the lactic acid oxidation by Cr（Ⅵ）. The reactivity of lactic acid depends upon the experimental conditions. It acts as a two- or three- equivalent reducing agent in the absence or presence of Mn（Ⅱ）. It was examined that Cr（Ⅲ） products resulting from the direct reduction of Cr（Ⅵ） by three-equivalent reducing agents. The oxidation of lactic acid follows the complex order kinetics with respect to [lactic acid]. The activation parameters Eo, △H^#, and AS^# were calculated and discussed.     

Synthesis, Crystal Structure and Properties of Complex VO（C10H9NO3） （C13H10NO2）

Complex VO(C10H9NO3)(C13H10NO2)(C10H9NO2-3=N-salicylidene-L-alaninate, C13H10NO-2=N-phenylbenzohydroxamate) was synthesized and characterized by means of elemental analysis, IR, UV, 1H NMR spectroscopies, cyclic voltammetry and single crystal X-ray diffraction. The complex crystallized in a monoclinic system with space group P21 and crystal cell parameters a=0.9720(1) nm, b=1.8274(2) nm, c=1.2542(1) nm, β=104.868(9)°, V=2.1532(4) nm3, Mr=470.34, Z=2. The two oxygen atoms and the one nitrogen atom of the tridentate Schiff base ligand and the one oxime oxygen atom of the hydroxamate ligand coordinate to the vanadium atom, forming an equatorial plane, the two axial positions are respectively occupied by the oxygen atom of the oxovanadium and the carbonyl oxygen atom of the hydroxamate and the vanadium atom exhibits a distorted octahedral VO(ONO)(OO) coordination sphere. The 1H NMR spectrum suggests that the two isomers, endo and exo in a molar ratio of 1/1.7, coexist in the solution of the title complex in CDCl3. There exists a quasi-reversible one-electron redox reaction corresponding to VⅤ/VⅥ couple in the three non-aqueous solvents, and the redox potential E1/2 of the title complex substantially shifts in the direction of the positive voltage increase in the order: CH2Cl2＜CH3CN＜DMF.     

Synthesis,Crystal Structure of Cis—dioxo—catecholatotungsten（VI） Complex and Its NMR Studies on the Interaction with ATP

Cis-dioxo-catecholatotungsten(VI) complex anion[W^(VI)O2-(OC6H4O)2]^2- was obtained with discrete protonated ethylenediamine (NH2CH2CH2NH3)^ cations by the reaction of tetrabutyl ammonium decatungstate with catechol in the mixed solvent of CH3OH,CH3CN and ethylenediamine,and compared with its molybdenum anaogue [Mo^(V) O2(OC6H4O)2]^3- by crystal structure,UV,EPR,The results of the UV and EPR spectra show that tungsten is less redox active than molybdenum since the molybdenum is reduced from Mo(VI) to Mo(V) but tungsten stays in the original highest oxidized state Mo(VI) when they are crystallized from the solution above.It is worthy to note that [W^(VI)O2(OC6H4O)]^2- shows the same coordination structure as its molybdenum analogue in which the metal center exhibits distorted octahedral coordination geometry with two cis-dioxocatecholate ligands and might have the related coordination structure feature with the cofactor of flavoenzyme because [Mo^(V)O2(OC6H4O)2]^3- presented essentially the same EPR spectra as flavoenzyme.The NMR studies on the interaction of the title complex with ATP reveal that the reduction of W(VI) to W(V) occurs when the title complex is dissolved in D2O and the W(V) is oxidized again when ATP solution is mixed with original solution and the hydrolysis of the catecholato ligand take places at mean time being monitored by ^1H NMR and ^13C NMR spectra.     

Mn(Ⅱ)和Ce(Ⅳ)离子对铬酸氧化乳酸的影响

The kinetics and mechanism of lactic acid oxidation in the presence of Mn(II)and Ce(IV)ions by chromic acid were studied spectrophotometrically.The oxidation of lactic acid by Cr(VI)was found to proceed in two measurable steps,both of which gave pyruvic acid as the primary product in the absence of Mn(II).2Cr(VI) 2CH3CHOHCOOH→2CH3COCOOH Cr(V) Cr(III)Cr(V) CH3CHOHCOOH→Cr(III) CH3COCOOH The observed kinetics was explained due to the catalytic and inhibitory effects of Mn(II)and Ce(IV)on the lactic acid oxidation by Cr(VI).The reactivity of lactic acid depends upon the experimental conditions.It acts as a two-or three-equivalent reducing agent in the absence or presence of Mn(II).It was examined that Cr(III)products resulting from the direct reduction of Cr(VI)by three-equivalent reducing agents.The oxidation of lactic acid follows the complex order kinetics with respect to [lactic acid].The activation parameters Ea,ΔH#,and ΔS# were calculated and discussed.     

Synthesis, Crystal Structure, UV-vis and EPR Studies of（ NH3CH2CH2NH2 ） 2.5 [ Mo0.5^（V）W0.5^（VI）O2 （ OC6H4O ） 2]

Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme.     

Electrooxidation of CO on Ru（0001） and RuO2（ 100） Electrode Surfaces

The electrooxidation of CO on Ru(0001) and RuO2(100) electrode surfaces were characterized by cyclic voltammetry,AES and RHEED,The CO adlayer was first partially oxidized at 0.8 V, which is controlled by the attack of oxygen species toward the Ru(0001) surface. The remaining CO aldayer oxidation at 0.55 V is related to the combination of CO molecules with oxygen species already located on the surface,In contrast,successive peaks on RuO2(100) at 0.4 V and 0.72 V are observed ,which shows that CO molecules can directly react with two different lattice-oxygen on the surface to carbon dioxide.     

Structural and Spectroscopic Studies on [Cu（DACH）2（H2O）]—Cl2（DACH—1,4—Diazacycloheptane）

A penta-coordinated Cu(Ⅱ） complex with 1,4-diazacycloheptane (DACH),[Cu(DACH)2(H2O)]Cl2(1),has been synthesized and characterized by X-ray diffraction,IR spectra,elemental analyses,thermal analyses,UV-Vis and ESR techniques.Complex 1 crystallizes in orthorhombic crystal system,Pbcn space group with a=1.6075(4),b=1.0539(3),c=0.9195(3)nm,V=1.5578(7)nm^3,Mr=352.79,Z=4,Dc=1.487g/cm^3,final R=0.0451 and wR=0.1294.The structure of 1 indicates that the central Cu(Ⅱ） atom is penta-coordinated by four nitrogen aboms of two DACH moieties at the equatorial positions and a water molecule at the axis position.The coordination geometry of Cu(Ⅱ） could be considered as an approximately ideal square-pyramidal environment.Both DACH rings arrange in cis-form and are predominantly in the boat-boat conformation (80%) with some disorder to the chair-chair conformation (20%).The Cl^- anions are hydrogen bonded with the nitrogen donors of the DACH rings and the oxygen donor of the coordinated H2O molecule to form a one-dimensional zigzag linear structure. The solution behaviors of 1 are also discussed in detail by Uvvis and ESR technique.     

Synthesis, Crystal Structure and Luminescence Property of a 2D Mn（II） Coordination Polymer Based on Isoniazid

A novel 2D Mn(Ⅱ) coordination polymer [Mn(CH3COO)2(INH)]n(INH=isoniazid) has been synthesized in DMF solution with isoniazid and Mn(CH3COO)2 . The polymer was characterized by single-crystal X-ray diffraction analysis, FTIR and X-ray powder diffraction (XRPD). The crystal belongs to the monoclinic system, space group P2 1 /c with a=9.3251(18), b=16.340(3), c=8.8096(17) , β=94.747(3)°, V=1337.7(4) 3 , Z=4, μ(MoKα)=1.006 mm -1 , F(000)=636, R=0.0754 and wR=0.1375 (I > 2σ(I)). In the complex, each Mn(Ⅱ) atom is coordinated to three CH3COO- groups and two INH ligands. The Mn(Ⅱ) atoms locate in a distorted coordination octahedron and are bridged by CH3COO- ions to form a 1D S shaped chain extending along the c direction. The INH molecules act as bridges to link the Mn(Ⅱ) atoms of adjacent chains and further construct a lamellar polymer. The remaining coordination site is occupied by an O atom of the other CH3COO-. The experimental results show that the title complex has good luminescence property and could be used as potential optical materials.     

Cleavage of the Fe—Fe Bond of （Me2SiSiMe2） [η^5－C5H4Fe（CO）2]2 with Na／Hg and Molecular Structure of the Ring－Opened Complex

The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain.     

Structure and Photosynthetic Mimicking of Bis(2,6-bis(benzimidazol-2-yl)pyridine)manganese(II)

Introduction　　Manganeseionsplayanimportantroleinthelight in ducedoxidationofwatertomolecularoxygeninphotosys temII (PSII)ofgreenplants.1 3Inrecentyears ,man ganesecomplexesofpolypyridineligands ,suchasbipyri dine ,1,10 phenanthrolineand 2 ,2′:6′,2″ terpyridine ,havehadconsiderableattentionasthecomplexesformedareusefulmodelsformanganese containingbimolecu lars .4 6 Therefore ,synthesisandcharacterizationofman ganeseinitsvariousoxidationstates ,withvariousligandtypesandnuclearities ,hav…     

Cerium(IV)‐Driven Water Oxidation Catalyzed by a Manganese(V)–Nitrido Complex

The study of manganese complexes as water‐oxidation catalysts (WOCs) is of great interest because they can serve as models for the oxygen‐evolving complex of photosystem II. In most of the reported Mn‐based WOCs, manganese exists in the oxidation states III or IV, and the catalysts generally give low turnovers, especially with one‐electron oxidants such as Ce^IV. Now, a different class of Mn‐based catalysts, namely manganese(V)–nitrido complexes, were explored. The complex [Mn^V(N)(CN)₄]²⁻ turned out to be an active homogeneous WOC using (NH₄)₂[Ce(NO₃)₆] as the terminal oxidant, with a turnover number of higher than 180 and a maximum turnover frequency of 6 min⁻¹. The study suggests that active WOCs may be constructed based on the Mn^V(N) platform.     

A Tri‐µ‐O‐S‐O Manganese Dimer: Synthesis,Structral and EPR Study

A Tri‐µ‐O‐S‐O coordinative manganese dimer: [Mn₂(SO₄)₂(phen)₄]·CH₃OH (phen1,10‐phenanthroline) ( 1 ) was yielded by the reaction of 1,10‐phenanthroline and MnSO₄·H₂O in a mixed solvent of methanol and acetonitrile under room temperature and was structurally characterized. Single crystal analysis shows that complex 1 has polymeric structure based on binuclear Mn(II) units bridged by O‐S‐O groups of two SO₄²⁻ anion. The UV spectrum of the complex clarifies that each metal‐organic building unit parallels with each other through the Π‐Π interactions of face‐to‐face separations of two 1,10‐phen planes among the complex, forming a layered structure. And the electronic paramagnetic resonance (EPR) signal clearly indicates that those manganese atoms in complex 1 are in +2 oxidation states.     

Synthesis and Magnetic Studies of Copper (II)‐Manganese (II) Heterobinuclear Complexes with an Oxamido Bridge

Four new copper (II)‐manganese (II) heterobinuclear complexes bridged byN, N'‐bis[2‐(dimethylamino)ethyl)]oxamido dianion (dmoxæ) and end‐capped with 1, 10‐phenanthroline (phen), 5‐methyl‐1, 10‐phenanthroline (Mephen), diaminoethane (en) or 1,3‐di‐aminopropane (pn). respectively, namely, [Cu(dmoxae)MnL₂] (CIO₄)₂ (L=phen, Mephen, en, pn), have been synthesized and characterized by elemental analyses, IR, electronic spectral studies, and molar conductivity measurements. The electronic reflectance spectrum indicates the presence of spin exchange‐coupling interaction between bridged copper(II) and manganese (II) ions. The cryomagnetic measurements (4.2‐300 K) of [Cu(dmoxae)Mn(phen)₂](CIO₄)₂ (1) and [Cu(dmoxae)Mn(Mephen)₂](CIO₄)₂(2) complexes demonstrated an antiferromagnetic interaction between the adjacent manganese(II) and copper (II) ions through the oxamido‐bridge within each molecule. On the basis of spin Hamiltonian, H= ‐ 2JS₁. S₂. the magnetic analysis was carried out for the two complexes and the spin‐coupling constant (J) was evaluated as ?35.9 cm^?1 for 1 and ‐ 32.6 cm^?1 for 2. The influence of methyl substitutions in the amine groups of the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is also discussed.     

A new two‐dimensional manganese(II) coordination polymer based on thiophene‐3,4‐dicarboxylic acid

A novel manganese coordination polymer, poly[(μ₅‐thiophene‐3,4‐dicarboxylato)manganese(II)], [Mn(C₆H₂O₄S)]_n, was synthesized hydrothermally using 3,4‐thiophenedicarboxylate (3,4‐tdc²⁻) as the organic linker. The asymmetric unit of the complex contains an Mn²⁺ cation and one half of a deprotonated 3,4‐tdc²⁻ anion, both residing on a twofold axis. Each Mn²⁺ centre is six‐coordinated by O atoms of bridging/chelating carboxylate groups from five 3,4‐tdc²⁻ anions, forming a slightly distorted octahedron. The Mn²⁺ centres are bridged by 3,4‐tdc²⁻ anions to give an infinite two‐dimensional layer which incorporates one‐dimensional Mn–O gridlike chains, and in which the 3,4‐tdc²⁻ anion adopts a novel hexadentate chelating and μ₅‐bridging coordination mode. The fully deprotonated 3,4‐tdc²⁻ anion exhibits unexpected efficiency as a ligand towards the Mn²⁺ centres, which it coordinates through all of its carboxylate O atoms to provide the novel coordination mode. The IR spectrum of the complex is also reported.     

Desulfuration and Cyclization of (Z)‐2‐[Amino(pyridine‐2‐yl)methylene]‐ hydrazonecarbothioamide in the Presence of Manganese(II)

The reaction of (Z)‐2‐[amino(pyridine‐2‐yl)methylene]hydrazonecarbothioamide (HAm4DH) with Mn(ClO₄)₂·6H₂O afforded different mononuclear or polynuclear manganese(II) complexes, the nature of which apparently depended on the solvent used. For example, in ethanol a compound of formula [Mn(HAm4DH)₂](ClO₄)₂ ( 1 ) was obtained, where HAm4DH coordinates as a common tridentate NNS donor, but the [Mn(bpy)₂(NCS)₂] complex ( 2 ) (bpy = 2,2'‐bipyridine) has also been obtained – probably due to C–N bond cleavage of the thiosemicarbazone. Nevertheless, in a basic aqueous medium [Mn(bpy)₃](ClO₄)₂·0.5bpy ( 3 ) is formed and there is structural evidence for chemical transformations of the thiosemicarbazone promoted by Mn^II. Thus, the sulfate in {[Mn(py)₄Mn(py)₂(H₂O)₂(μ‐SO₄)₂]·4H₂O}_n ( 4 ) or sulfate and cyclooctasulfur in [Mn(pta)₂(pdo)]₄(SO₄)₂·4H₂O·S₈] ( 5 ), where pta is 3‐(pyridin‐2‐yl)‐1,2,4‐triazol‐5‐amine and pdo is (2R,4R/2S,4S)‐pentane‐2,4‐diolato, arise from the desulfuration and oxidation of the thiosemicarbazone ligand. The structures of complexes 2 to 5 were established by single‐crystal X‐ray diffraction. The formation of pta is the result of the oxidative cyclization of HAm4DH. In the polynuclear complex 4 , the sulfate acts as an (O,O') bridge between alternating Mn(py)₂(H₂O)₂ and Mn(py)₄ centers. In the tetranuclear complex 5 , pta acts as a bischelating ligand through the N‐pyridine and N‐triazole, and pdo act as a bridge between two manganese atoms. It is also noteworthy that in complexes 4 and 5 hydrogen bonds give rise to different self‐assembly behaviour that leads to complicated supramolecular structures.     

Bis[S‐6‐(2,2:6′,2′′‐terpyridin‐4′‐yloxy)hexyl thioacetate]manganese(II) bis(hexafluorophosphate)

The structure of a manganese(II) complex of terpyridine functionalized with acetylsulfanyl‐terminated hexyloxy chains, [Mn(C₂₃H₂₅N₃O₂S)₂](PF₆)₂, is described. This type of complex is of interest in the study of single‐molecule transport properties in open‐shell systems. The manganese coordination environment is distorted octahedral but, importantly, with no larger deviations from the idealized geometry than those observed for other metal–terpyridine complexes. The Mn—N bond lengths range from 2.192 (2) to 2.272 (3) Å. The title compound crystallizes with the cation and anions all on general positions, with the hexafluorophosphate anions exhibiting orientational disorder. When compared with other bis‐terpyridine complexes, this structure demonstrates that manganese(II) is no more prone to undergo low‐symmetry distortions than systems with ligand field stabilization energy contributions.     

混合价双核锰[Mn2(cyclen)2(μ-O)2](ClO4)3·4H2O的晶体结构和表征

The mixed-valence manganese(Ⅲ/Ⅳ) complex [Mn2(cyclen)2(μ-O)2](ClO4)3-4H2O (1) (cyclen=1,4,7,10-tetraazacyclododecan) with chemical formula C16H48Cl3Mn2N8O18 has been synthesized and characterized by single crystal X-ray diffraction analysis, elemental analysis, IR and electronic spectra. The results showed that the manganese(Ⅲ/Ⅳ) ions were six-coordinated by four nitrogen atoms from cyclen and two oxygen atoms from the oxygen bridge, forming a distorted octahedron geometry. There were two very strong peaks in the range of 400-700 nm in electronic spectrum, which was similar to Mn catalase and Mn ribonucleotide reductase extracted from organisms.Electrochemical study indicated that the complex underwent a quasi-reversible one-electron reduction and oxidation at E1/2=0.827 V in acetonitrile.     

Solvothermal Synthesis and Crystal Structures of Two Manganese Complexes [Mn(II)(acac−)2(4,4′‐bipy)]n (bipy=4,4′‐bipyridine) and [Mn(III)(acac−)3]·4CO(NH2)2

Two special manganese complexes [Mn(II)(acac^?)₂(4,4′‐bipy)]_n (bipy=4,4′‐bipyridine) (complex 1 ) and [Mn(III)(acac^?)₃]·4CO(NH₂)₂ (acacH=acetylacetone) (complex 2 ) were synthesized in the same strategy by solvothermal method. Single crystal X‐ray diffraction revealed the complex 1 consists of one‐dimensional infinite coordination chain, with the manganese centers bridged by 4,4′‐bipy. And free carbamides of complex 2 connect with each other through the hydrogen bonds to form a 14‐membered carbamide ring and a zig‐zag plane. Both enantiomers of Mn(III)(acac^?)₃ exist in the structure, forming a racemate. Furthermore, these enantiomers and those zig‐zag planes are linked with hydrogen bonds to form an unique spatial network.     

Redox characteristics of manganese and cobalt complexes obtained from pyridine N-oxide

Manganese and cobalt complexes, using pyridine N-oxide as ligand, have been synthesized, and their cyclic and square-wave voltammetric measurements have been carried out. The results reveal that the complexes exhibit different voltammetric pattern, which suggests that the redox processes are most probably metal-centered. In both complexes, extra redox activity is observed once the potential exceeds certain value of the voltage. The observation of an oxidation wave in manganese complex at + 0.75 V vs. Ag/AgCl or + 0.95 V vs. NHE strongly suggests that this complex can bring about oxidation of water and can, thus, serve as a synthetic analogue of water oxidizing complex (WOC) of PS II.