A new organometallic heteropolytungstate related to [Sb2W22O74(OH)2](12-): synthesis and structural characterisation of the bis-{Ru(p-cymene)}(2+)-containing anion [Sb2W20O70{Ru(p-cymene)}2](10-)

The easy synthesis of [Sb2W20O70{Ru(p-cymene)}2](10-) by the reaction between the organometallic precursor [Ru(p-cymene)Cl2]2 and [Sb2W20O70]14-, formed in situ, confirms the importance of the organometallic route to well defined ruthenium(+II)-substituted heteropolytungstates.     

Physicochemical characterization of the dimeric lanthanide complexes [en{Ln(DO3A)(H2O)}2] and [pi{Ln(DTTA)(H2O)}2]2-: a variable-temperature 17O NMR study

The Gd(III) complexes of the two dimeric ligands [en(DO3A)2] {N,N'-bis[1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-10-yl-methylcarbonyl]-N,N'-ethylenediamine} and [pi(DTTA)2]8- [bisdiethylenetriaminepentaacetic acid (trans-1,2-cyclohexanediamine)] were synthesized and characterized. The 17O NMR chemical shift of H2O induced by [en{Dy(DO3A)}2] and [pi{Dy(DTTA)}2]2- at pH 6.80 proved the presence of 2.1 and 2.2 inner-sphere water molecules, respectively. Water proton spin-lattice relaxation rates for [en{Gd(DO3A)(H2O)}2] and [pi{Gd(DTTA)(H2O)}2]2- at 37.0 +/- 0.1 degrees C and 20 MHz are 3.60 +/- 0.05 and 5.25 +/- 0.05 mM(-1) s(-1) per Gd, respectively. The EPR transverse electronic relaxation rate and 17O NMR transverse relaxation time for the exchange lifetime of the coordinated H2O molecule and the 2H NMR longitudinal relaxation rate of the deuterated diamagnetic lanthanum complex for the rotational correlation time were thoroughly investigated, and the results were compared with those reported previously for other lanthanide(III) complexes. The exchange lifetimes for [en{Gd(DO3A)(H2O)}2] (769 +/- 10 ns) and [pi{Gd(DTTA)(H2O)}2]2- (910 +/- 10 ns) are significantly higher than those of [Gd(DOTA)(H2O)]- (243 ns) and [Gd(DTPA)(H2O)]2- (303 ns) complexes. The rotational correlation times for [en{Gd(DO3A)(H2O)}2] (150 +/- 11 ps) and [pi{Gd(DTTA)(H2O)}2]2- (130 +/- 12 ps) are slightly greater than those of [Gd(DOTA)(H2O)]- (77 ps) and [Gd(DTPA)(H2O)]2- (58 ps) complexes. The marked increase in relaxivity (r1) of [en{Gd(DO3A)(H2O)}2] and [pi{Gd(DTTA)(H2O)}2]2- result mainly from their longer rotational correlation time and higher molecular weight.     

Synthesis, characterization, and photochemical behavior of {Ru(arene)}2+ derivatives of alpha-[PW11O39]7-: an organometallic way to ruthenium-substituted heteropolytungstates

Reaction of [Ru(arene)Cl(2)](2) (arene = benzene, toluene, p-cymene, hexamethylbenzene) with K(7)[PW(11)O(39)].14H(2)O provided two series of organometallic derivatives of heteropolytungstates: type-1 and type-2 complexes of general formulas [PW(11)O(39){Ru(arene)(H(2)O)}](5-) and [{PW(11)O(39){Ru(arene)}}(2){WO(2)}](8-), respectively. All compounds were characterized by infrared and multinuclear NMR ((1)H, (31)P, (183)W) spectroscopies. The crystal structures of Na(4)K(4)[{PW(11)O(39){Ru(benzene)}}(2){WO(2)}].6H(2)O (NaK-2a.6H(2)O), K(7)H[{PW(11)O(39){Ru(toluene)}}(2){WO(2)}].4H(2)O (K-2b.4H(2)O), and Cs(3)K(2)[PW(11)O(39){Ru(p-cymene)(H(2)O)}].4H(2)O (CsK-1c.4H(2)O) were obtained and revealed that the {Ru(arene)} fragment is supported on the oxometallic framework. Photochemical reactivity of [PW(11)O(39){Ru(arene)(H(2)O)}](5-) (arene = toluene, p-cymene) in the presence of various ligands L (L = H(2)O, dimethyl sulfoxide, tetramethylene sulfoxide, and diphenyl sulfoxide) was investigated, and led to the formation of [PW(11)O(39){Ru(L)}](5-), in which the ruthenium is incorporated into the lacunary [PW(11)O(39)](7-) anion.     

Two wheel-like polytungstates obtained by incorporation of two {Cu(4)} clusters and two molybdenum centers in the {W(48)} wheel

Two new {P(8)W(48)} wheel-based compounds, Na(12)Li(16){[Cu(H(2)O)](2)[Cu(4)(OH)(4)(H(2)O)(8)](2)P(8)W(48)O(184)}·55H(2)O (1), and K(4)Na(24)Li(10){(MoO(2))(2)(P(8)W(48)O(184))}·61H(2)O (2) have been synthesized by a conventional aqueous solution method, and characterized by UV, IR, TG analysis, XPRD, (31)P NMR, XPS, single-crystal X-ray diffraction analyses, magnetic study and electrochemistry study. In compound 1, a wheel-type {P(8)W(48)} containing two {Cu(4)} clusters and two isolated Cu cations results in a 10-Cu-containing polyoxotungstate, which represents the first {P(8)W(48)}-based compound trapping two transition metal (TM) clusters in its inner cavity. Further, the polyoxoanion was connected by Na(+) and Li(+) cations into a 3D framework. Compound 2 is a 2-Mo-containing {P(8)W(48)}-based polyoxotungstate. Magnetic study indicates that antiferromagnetic interactions exist in compound 1.     

Substitution, cage functionalization, and oxidation of the charge-compensated triruthenium monocarbollide cluster complex [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8

The compound [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8] 1a reacts with PMe3 or PCy3(Cy = cyclo-C6H11) to give the structurally different species [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)5(PMe3)}-closo-2,1-RuCB10H8] 4 and [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(CO)5(PCy3)}-closo-2,1-RuCB10H8]5, respectively. A symmetrically disubstituted product [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)4(PMe3)2}-closo-2,1-RuCB10H8] 6 is obtained using an excess of PMe3. In contrast, the chelating diphosphines 1,1'-(PPh2)2-Fe(eta-C5H4)2 and 1,2-(PPh2)2-closo-1,2-C2B10H10 react with 1a to yield oxidative-insertion species [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(micro-[1',1'-(PPh2)2-Fe(eta-C5H4)2])(CO)4}-closo-2,1-RuCB10H8] 7 and [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(CO)4(1',2'-(PPh2)2-closo-1',2'-C2B10H10)}-closo-2,1-RuCB10H8] 8, respectively. In toluene at reflux temperatures, 1a with Bu(t)SSBu(t) gives [1-SMe2-2,2-(CO)2-7-(mu-SBu(t))-11-(mu-H)-2,7,11-{Ru2(mu-H)(mu-SBu(t))(CO)4}-closo-2,1-RuCB10H8] 9, and with Bu(t)C [triple bond] CH gives [1-SMe2-2,2-(CO)2-7-{mu:eta2-(E)-CH=C(H)Bu(t)}-11-{mu:eta2-(E)-CH=C(H)Bu(t)}-2,7,11-{Ru2(CO)5}-closo-2,1-RuCB10H8] 10. In the latter, two alkyne groups have inserted into cage B-H groups, with one of the resulting B-vinyl moieties involved in a C-H...Ru agostic bond. Oxidation of 1a with I2 or HgCl2 affords the mononuclear ruthenium complex [1-SMe2-2,2,2-(CO)3-closo-2,1-RuCB10H10] 11.     

Tetrakis(dimethyltin)-containing tungstophosphate [{Sn(CH3)2}4(H2P4W24O92)2]28-: first evidence for a lacunary Preyssler ion

We demonstrate for the first time that the superlacunary polyanion [H(2)P(4)W(24)O(94)](22)(-) reacts with electrophiles. One-pot reaction of this precursor polyanion with dimethyltin dichloride in aqueous acidic medium results in the hybrid organic-inorganic [{Sn(CH(3))(2)}(4)(H(2)P(4)W(24)O(92))(2)](28)(-) (1). Single-crystal X-ray analysis was carried out on K(17)Li(11)[{Sn(CH(3))(2)}(4)(H(2)P(4)W(24)O(92))(2)].51H(2)O (1a), which crystallizes in the tetragonal system, space group P4(2)/nmc, a = b = 21.5112(17) and c = 27.171(3) A, and Z = 2. Polyanion 1 is composed of two (P(4)W(24)O(92)) fragments that are linked by four equivalent diorganotin groups. The unprecedented assembly 1 has D(2)(d)() symmetry and contains a hydrophobic pocket in the center of the molecule. The cyclic voltammetry pattern of 1 is constituted by a first broad, 16-electron reduction wave followed by a second large current intensity wave. No splitting of the first reduction wave could be obtained at moderate scan rate values, even though two well-separated oxidation processes are associated with it. The characteristics of the first wave are clearly different from those obtained for the polyanion precursor [H(2)P(4)W(24)O(94)](22)(-) and the related, wheel-shaped [H(7)P(8)W(48)O(184)](33)(-), which is due to the {Sn(CH(3))(2)} fragments in 1. However, no feature was observed in the voltammogram which could be associated with reduction of the Sn centers.     

Extended polyoxometalate framework solids: two Mn(II)-linked {P8W48} network arrays

Two polyoxometalate open framework (POMOF) materials have been synthesized using a secondary building unit (SBU) approach that facilitates the convergent assembly of multidimensional framework materials using a preassembled anionic SBU {P(8)W(48)}, with integrated "pore" 1 nm in diameter, and electrophilic manganese {Mn(2+)} linkers. This yields two new POMOFS with augmented hexagonal tiling (2 and 3), related to a known three-dimensional (3D) cubic array K(18)Li(6)[Mn(II)(8)(H(2)O)(48)P(8)W(48)O(184)]·108H(2)O (1), K(12)[Mn(II)(14)(H(2)O)(30)P(8)W(48)O(184)]·111H(2)O (2), and K(8)Li(4)[Mn(II)(14)(H(2)O)(26)P(8)W(48)O(184)]·105H(2)O (3). These frameworks have been crystallized from aqueous Li-buffered solutions of {P(8)W(48)} and Mn(II)(ClO(4))(2)·6H(2)O via careful control of the synthetic strategy akin to a crystal engineering approach using cation and temperature control to isolate different material architectures shown by compounds 1-3.     

STM/STS observation of polyoxoanions on HOPG surfaces: the wheel-shaped [Cu20Cl(OH)24(H2O)12(P8W48O184)]25- and the ball-shaped [{Sn(CH3)2(H2O)}24{Sn(CH3)2}12(A-PW9O34)12]36-

A combination of scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) techniques have been performed on the wheel-shaped [Cu20Cl(OH)24(H2O)12(P8W48O184)]25- and the ball-shaped [{Sn(CH3)2(H2O)}24{Sn(CH3)2}12(A-PW9O34)12]36- deposited on highly oriented pyrolytic graphite surfaces. Small, regular molecule clusters, as well as separated single molecules, were observed. The size of the molecules is in agreement with the data determined by X-ray crystallography. In STS measurements, we found a rather large contrast at the expected location of the Cu metal centers in our molecules, i.e., the location of the individual Cu ions in their organic matrix is directly addressable by STS.     

Novel ruthenium(ii) complexes containing the N-phosphorylated iminophosphorane-phosphine ligand Ph(2)PCH(2)P{[double bond, length as m-dash]NP([double bond, length as m-dash]O)(OEt)(2)}Ph(2): a new coordination mode of its methanide anion

The reactivity of complex [Ru(eta(6)-p-cymene)(kappa(3)P,N,O-Ph(2)PCH(2)P{[double bond, length as m-dash]NP([double bond, length as m-dash]O)(OEt)(2)}Ph(2))][SbF(6)](2) towards a variety of mono- and bidentate neutral ligands has been studied, allowing the high-yield synthesis of the novel half-sandwich Ru(ii) derivatives [Ru(eta(6)-p-cymene)(L)(kappa(2)P,O-Ph(2)PCH(2)P{[double bond, length as m-dash]NP([double bond, length as m-dash]O)(OEt)(2)}Ph(2))][SbF(6)](2) (L = N[triple bond, length as m-dash]CMe , N[triple bond, length as m-dash]CEt , PMe(3), PMe(2)Ph , PMePh(2), PPh(3), P(OMe)(3), P(OEt)(3), P(OPh)(3), py , kappa(1)P-dppm , kappa(1)P-dppe ), as well as the octahedral species [Ru(Ninsertion markN)(2)(kappa(2)P,O-Ph(2)PCH(2)P{[double bond, length as m-dash]NP([double bond, length as m-dash]O)(OEt)(2)}Ph(2))][SbF(6)](2) (Ninsertion markN = bipy , phen ). Deprotonation of complexes ,, upon treatment with an excess of NaOH in CH(2)Cl(2), generates the monocationic derivatives [Ru(Ninsertion markN)(2)(kappa(2)P,N-Ph(2)PC(H)[double bond, length as m-dash]P{NP([double bond, length as m-dash]O)(OEt)(2)}Ph(2))][Cl] (Ninsertion markN = bipy , phen ) in which the methanide anion adopts an unprecedented kappa(2)P,N bidentate coordination mode. The structures of compounds , and have been determined by single-crystal X-ray diffraction methods.     

Synthesis and Structure of One Novel Polyoxometalate Compound Connected via Cerium(Ⅲ) Cation with Three-dimensional Framework H2{[K(H2O)2]2[Ce(H2O)5]2(H2Mo1.16W10.84O42)}·8H2O

One novel polyoxometalate compound connected via trivalent cerium cation as bridge H2{[K(H2O)2]2[Ce(H2O)5]2(H2Mo1.16W10.84O42)}·8H2O 1 was designed and synthesized in aqueous solution. X-ray diffraction analysis reveals that the structure of 1 is a three-dimensional framework assembled from the arrangement of H2Mo1.16W10.84O42 (named paradodecmetalate-B) and Ce(H2O)53 containing two planes, which are constructed through the unification of H2Mo1.16W10.84O4210- and Ce(H2O)53 along the [100] and [001] directions. Crystal data: H96Ce4K4Mo2.32O128W21.68, Mr = 7074.89, monoclinic, P21/n, a = 12.5037(17), b = 17.002(2), c = 12.7473(17) (A), β = 105.966(2)°, V = 2605.4(6) (A)3, Z = 1, Dc = 4.509 g/cm3, F(000) = 3132, μ = 26.098 mm(1, R = 0.0377 and wR = 0.0789 (I ＞ 2σ(I)).     

Synthesis, Structure, and Magnetic Properties of One Polyoxometalate (W/Mo) Compound: H8K{[Ni(H2O)5]2(H2Mo1.80W10.20O42)}Cl3·16H2O

One new polyoxometalate compound connected via nickel/potassium cations, H8K{[Ni(H2O)5]2(H2Mo1.80W10.20O42)}Cl3·16H2O 1, was prepared and characterized by elemental analysis and IR spectroscopy. Single-crystal X-ray diffraction analysis results reveal that clusters of [Ni(H2O)5]2(H2Mo1.80W10.20O42)}6-in compound 1 are linked by potassium cations to form one- dimiensional chains, based on which a three-dimensional network is further constructed via the hydrogen bonds of O…O and O…Cl. Magnetic measurements show that compound 1 has para- magnetic properties. Crystal data: H62Cl3KMo1.80Ni2O68W10.20, Mr = 3461.33, monoclinic, space group C2/c, a = 18.9291(19), b = 16.6758(17), c = 19.1064(19)(A), β = 106.6880(10)(, V = 5777.1(10) (A)3, Z = 4, Dc = 3.980 g/cm3, F(000) = 6250, μ = 21.574 mm(1, R = 0.0579 and wR = 0.1623 (Ⅰ ＞ 2σ(I)).     

CRYSTAL STRUCTURE OF [Cu(NH3)2]2[{Cu(NH3)}2{Cu(NH3)(OH)}Re6Se8(CN)6]

Journal of Structural Chemistry - Chain coordination polymer [Cu(NH3)2]2[{Cu(NH3)}2{Cu(NH3)(OH)}Re6Se8(CN)6] (1) is obtained by a reaction of Cs2.75K1.25[Re6Se8(CN)4(OH)2]·H2O with CuCN in the...     

An Unprecedented 1D Zigzag Chain Alkaline Earth Metal Derivative {[Ba(DMF)_3(H_2O)_2][Ba(DMF)_4]_2(P_2W_(18)O_(62))}_n Containing Dawson Heteropolyanion

Most of the polyoxometalates have discrete structures of definite sizes and shapes belonging to well-known structural types, such as the Lindquist, Keggin, Dawson, Strandberg, or Anderson1–2. Linking these discrete entities to build solid-state materials…     

Ln(terpy)]3+ (Ln = Sm, Gd) entity forms isolated magnetic chains with [W(CN)8]3-

The reaction between Ln(NO3)3*xH2O, Cs3[W(V)(CN)8]*H2O and 2,2':6',2'-terpyridine (terpy) leads to the original isomorphous cyano-bridged [Ln(III)(terpy)(DMF)4][W(V)(CN)8] *6H2O [Ln = Gd (1), Sm (2)] 1-D chains. The crystal structures of {Ln(III)W(V)} chains and consist of alternating {[W(CN)8]} and {[Ln(terpy)]} building blocks. The neighbouring 1-D chains are weakly linked through pi-pi stacking interactions of the aromatic rings leading to 2-D supramolecular layers. The layers are linked through hydrogen bonds between H2O molecules and terminal cyano ligands. Magnetic studies revealed a weak antiferromagnetic coupling (J = -2.3(2) K) within the {Gd(III)W(V)} chains in . The positive effective coupling constant J = +2.0(5) K between the total angular momentum of the Sm(III) centre and the spin of the W(v) ion is equivalent to an antiferromagnetic character of the spin coupling between both centres in the {Sm(III)W(V)} chains of 2. The magnetic measurements suggest that they display an isolated magnetic chain behaviour.     

Preparation and Tungsten-183 NMR Characterization of [alpha-1-P(2)W(17)O(61)](10)(-), [alpha-1-Zn(H(2)O)P(2)W(17)O(61)](8)(-), and [alpha-2-Zn(H(2)O)P(2)W(17)O(61)](8)(-)

The preparation of the alpha-1 and alpha-2 isomers of the Wells-Dawson 17 tungsto derivatives by standard methods is accompanied by a significant proportion of the other isomer present as an impurity. In this study, the alpha-1 and alpha-2 isomers of [Zn(H(2)O)P(2)W(17)O(61)](8)(-) have been prepared in >98% purity by reacting isomerically pure K(9)Li[alpha-1-P(2)W(17)O(61)] and K(10)[alpha-2-P(2)W(17)O(61)], respectively, with ZnCl(2), while rigorously controlling the pH at 4.7. The molecules were isolated as potassium salts. For (183)W NMR and (31)P NMR characterization, both molecules were ion exchanged by cation-exchange chromatography, maintaining the pH at 4.7, to obtain the lithium salts. Removal of water and isolation of a solid sample of [alpha-1-Zn(H(2)O)P(2)W(17)O(61)](8)(-) was achieved by lyophilization at -40 degrees C. The chemical shift data from (31)P and (183)W NMR spectroscopy of the isolated [alpha-1-Zn(H(2)O)P(2)W(17)O(61)](8)(-) and [alpha-2-Zn(H(2)O)P(2)W(17)O(61)](8)(-) isomers are consistent with a mixture of the alpha-1 and alpha-2 isomers reported previously;(1) the molecules have the expected C(1) and C(s)() symmetry, respectively. The [alpha-1-Zn(H(2)O)P(2)W(17)O(61)](8)(-) isomer is stable in the pH range of 4.6-6 at temperatures <35 degrees C. Using the same ion exchange and lyophilization techniques, the lacunary [alpha-1-P(2)W(17)O(61)](10)(-) isomer was isolated as the lithium salt; characterization by (183)W NMR spectroscopy confirms the C(1) symmetry.     

{W48} ring opening: Fe16-containing, Ln4-stabilized 49-tungsto-8-phosphateopen wheel [Fe16O2(OH)23(H2O)9(P8W49O189)Ln4(H2O)20]11-

Wheely: For the first time and very unexpectedly, a rupture of the very stable {P(8)W(48)} wheel was observed in aqueous solution at pH?4 and 80?°C in the presence of Fe(III), Eu(III)/Gd(III), and H(2)O(2). This inorganic ring opening is unprecedented in polyoxometalate chemistry.     

新型环形聚阴离子[{WO(H_2O)}_3(AsW_8O31)_3]~21-的结构及表征

在pH=3.0的水溶液中，Na_2WO_4·2H_2O与NaAsO_2·6H_2O和NH_4Cl反应，得 到了新的杂多钨酸盐(MH_4)_19Na_2[{WO(H_2O)}_3(AsW_8O31)_3]·45H_2O单晶， 用X射线单晶衍射法及元素分析确定了其结构，晶体属单斜晶系，空间群C2/c，晶 胞参数为：a=3.1165(11)nm, b=1.7388(7)nm, c=2.2789(9)nm, β=97.342(6)°, V=12.248(8)nm~3, Z=4, R_1=0.0571,wR_2=0.0741[I＞2σ(I)]. 环型聚阴离子 [{WO(H_2O)}_3(AsW_8O31)_3]~21-是由三个{WO(H_2O)}桥连三个新发现的 {AsW_8O31}单元构成的，环聚离子[{WO(H_2O)}_3(AsW_8O31)_3]~21-具有近似D_ (3h)对称性。对该化合物还进行了~183W NMR, IR和TG表征。     

Dititanium-containing 19-tungstodiarsenate(III) [Ti2(OH)2As2W19O67(H2O)]8-: synthesis, structure, electrochemistry, and oxidation catalysis

The dititanium-containing 19-tungstodiarsenate(III) [Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)](8-) (1) has been synthesized and characterized by IR, TGA, elemental analysis, electrochemistry, and catalytic studies. Single-crystal X-ray analysis was carried out on Cs(8)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)].2CsCl.12H(2)O (Cs-1), which crystallizes in the monoclinic system, space group P2(1)/m, with a=12.7764(19), b=19.425(3), c=18.149(3) A, beta=110.234(3) degrees, and Z=2. Polyanion 1 comprises two (B-alpha-As(III)W(9)O(33)) Keggin moieties linked through an octahedral {WO(5)(H(2)O)} fragment and two unprecedented square-pyramidal {TiO(4)(OH)} groups, leading to a sandwich-type structure with nominal C(2v) symmetry. Synthesis of 1 was accomplished by reaction of TiOSO(4) and K(14)[As(2)W(19)O(67)(H(2)O)] in a 2:1 molar ratio in aqueous, acidic medium (pH 2). Polyanion 1 could also be isolated as a tetra-n-butyl ammonium (TBA) salt, {(n-C(4)H(9))(4)N}(5)H(3)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)] (TBA-1). TBA-1 was studied by cyclic voltammetry in acetonitrile (MeCN) solutions containing 0.1 M LiClO(4) and compared with the results obtained with Cs-1 in aqueous media. In MeCN, the Ti(IV) and W(VI) waves could not be separated distinctly. An important adsorption phenomenon on the glassy carbon working electrode was encountered both in cyclic voltammetry and in controlled potential electrolysis and was confirmed by Electrochemical Quartz Crystal Microbalance (EQCM) studies on a carbon film. TBA-1, dissolved in MeCN, reacts with H(2)O(2) to give peroxo complexes stable enough for characterization by UV-visible spectroscopy, cyclic voltammetry, and EQCM. TBA-1 shows high catalytic activity (TOF=11.3 h(-1)) in cyclohexene oxidation with aqueous H(2)O(2) producing products typical of a heterolytic oxidation mechanism. The stability of TBA-1 under turnover conditions was confirmed by using IR, UV-visible spectroscopy as well as cyclic voltammetry.     

Mixed-metal sandwich complexes [M(II)2(H2O)2Fe(III)2(P2W15O56)2]14- (M(II) = Co, Mn): synthesis and stability. The molecular structure of [M(II)2(H2O)2Fe(III)2(P2W15O56)2]14-

Two new mixed-metal sandwich complexes [M(II)2(H2O)2Fe(III)2(P2W15O56)2]14- (abbreviated [M2Fe2P4W30], M(II) = Co(II), Mn(II)) were obtained at pH 3 by addition of M2+ to [Na2(H2O)2Fe(III)2(P2W15O56)2]16- (abbreviated [Na2Fe2P4W30]) without substitution in the alpha-[P2W15O56]12- (abbreviated [P2W15]) units. Their X-ray structures are reported. At lower pH, back conversion to [Na2Fe2P4W30] was followed by 31P NMR, electrochemistry and UV-visible spectroscopy. The preparation and the characterization in solution of the lacunary intermediate [NaCo(II)(H2O)2Fe(III)2(P2W15O56)2]15- (abbreviated [NaCoFe2P4W30]) is also described.     

Synthesis and intramolecular and interionic structural characterization of half-sandwich (arene)ruthenium(II) derivatives of bis(pyrazolyl)alkanes

Arene ruthenium(II) complexes containing bis(pyrazolyl)methane ligands have been prepared by reacting the ligands L' (L' in general; specifically L(1) = H(2)C(pz)(2), L(2) = H(2)C(pz(Me2))(2), L(3) = H(2)C(pz(4Me))(2), L(4) = Me(2)C(pz)(2) and L(5) = Et(2)C(pz)(2) where pz = pyrazole) with [(arene)RuCl(mu-Cl)](2) dimers (arene = p-cymene or benzene). When the reaction was carried out in methanol solution, complexes of the type [(arene)Ru(L')Cl]Cl were obtained. When L(1), L(2), L(3), and L(5) ligands reacted with excess [(arene)RuCl(mu-Cl)](2), [(arene)Ru(L')Cl][(arene)RuCl(3)] species have been obtained, whereas by using the L(4) ligand under the same reaction conditions the unexpected [(p-cymene)Ru(pzH)(2)Cl]Cl complex was recovered. The reaction of 1 equiv of [(p-cymene)Ru(L')Cl]Cl and of [(p-cymene)Ru(pzH)(2)Cl]Cl with 1 equiv of AgX (X = O(3)SCF(3) or BF(4)) in methanol afforded the complexes [(p-cymene)Ru(L')Cl](O(3)SCF(3)) (L' = L(1) or L(2)) and [(p-cymene)Ru(pzH)(2)Cl]BF(4), respectively. [(p-cymene)Ru(L(1))(H(2)O)][PF(6)](2) formed when [(p-cymene)Ru(L(1))Cl]Cl reacts with an excess of AgPF(6). The solid-state structures of the three complexes, [(p-cymene)Ru{H(2)C(pz)(2)}Cl]Cl, [(p-cymene)Ru{H(2)Cpz(4Me))(2)}Cl]Cl, and [(p-cymene)Ru{H(2)C(pz)(2)}Cl](O(3)SCF(3)), were determined by X-ray crystallographic studies. The interionic structure of [(p-cymene)Ru(L(1))Cl](O(3)SCF(3)) and [(p-cymene)Ru(L')Cl][(p-cymene)RuCl(3)] (L' = L(1) or L(2)) was investigated through an integrated experimental approach based on NOE and pulsed field gradient spin-echo (PGSE) NMR experiments in CD(2)Cl(2) as a function of the concentration. PGSE NMR measurements indicate the predominance of ion pairs in solution. NOE measurements suggest that (O(3)SCF(3))(-) approaches the cation orienting itself toward the CH(2) moiety of the L(1) (H(2)C(pz)(2)) ligand as found in the solid state. Selected Ru species have been preliminarily investigated as catalysts toward styrene oxidation by dihydrogen peroxide, [(p-cymene)Ru(L(1))(H(2)O)][PF(6)](2) being the most active species.