Dilacunary decatungstates functionalized by organometallic ruthenium(II), [{Ru(C6H6)(H2O)}{Ru(C6H6)}(gamma-XW10O36)]4- (X = Si, Ge)

The benzene-Ru(II)-supported dilacunary decatungstosilicate [{Ru(C6H6)(H2O)}{Ru(C6H6)}(gamma-SiW10O36)]4- and the isostructural decatungstogermanate [{Ru(C6H6)(H2O)}{Ru(C6H6)}(gamma-GeW10O36)]4- have been synthesized and characterized by multinuclear solution NMR, IR, elemental analysis, and electrochemistry. Single-crystal X-ray analysis was carried out on K4[{Ru(C6H6)(H2O)}{Ru(C6H6)}(gamma-SiW10O36)].9H2O (K-1), which crystallizes in the orthorhombic system, space group Pmn2(1), with a = 13.6702(3) A, b = 16.2419(4) A, c = 12.1397(2) A, and Z = 2, and on K4[{Ru(C6H6)(H2O)}{Ru(C6H6)}(gamma-GeW10O36)].7H2O (K-2), which also crystallizes in the orthorhombic system, space group Pmn2(1), with a = 13.6684(12) A, b = 16.297(2) A, c = 12.1607(13) A, and Z = 2. Polyanions 1 and 2 consist of a Ru(C6H6)(H2O) group and a Ru(C6H6) group linked to a dilacunary (gamma-XW10O36) Keggin fragment resulting in an assembly with idealized Cs symmetry. The Ru(C6H6)(H2O) group is bound at the lacunary polyanion site via two Ru-O(W) bonds, whereas the Ru(C6H6) group is bound on the side via three Ru-O(W) bonds. Polyanions 1 and 2 were synthesized in aqueous acidic medium at pH 2.5 by the reaction of [Ru(C6H6)Cl2]2 with [gamma-SiW10O36]8- and [gamma-GeW10O36]8-, respectively. The formal potentials are roughly the same for the first W waves of 1 and 2. However, important differences appear for the second W waves. These observations indicate different acid-base properties for the reduced forms of 1 and 2. Three oxidation processes were detected: the oxidation of the Ru center is followed first by irreversible electrocatalytic processes of the Ru-benzene moiety and then of the electrolyte. Comparison of this behavior with that of the precursor reagent, [Ru(C6H6)Cl2]2, was useful to understand the main oxidation processes. A ligand substitution reaction was observed upon addition of dimethyl sulfoxide (dmso) to 1, 2, or [Ru(C6H6)Cl2]2. This reaction facilitates substantially the oxidation of the Ru center. The dmso was oxidized with large electrocatalytic currents more efficiently in the presence of 1 and 2 than with [Ru(C6H6)Cl2]2.     

The ruthenium(II)-supported heteropolytungstates [Ru(dmso)3(H2O)-XW11O39]6- (X = Ge, Si)

The novel Ru(II)-supported heteropolytungstates [Ru(dmso)(3)(H(2)O)XW(11)O(39)](6-)(X = Ge, Si) have been synthesized and characterized by single-crystal X-ray diffraction, multinuclear NMR ((183)W, (13)C, (1)H, (29)Si) and IR spectroscopy, elemental analysis and electrochemistry. The novel polyanion structure consists of a Ru(dmso)(3)(H(2)O) unit linked to a monolacunary [XW(11)O(39)](8-) Keggin fragment via two Ru-O-W bonds resulting in an assembly with C(1) symmetry. Polyanions 1 and 2 were synthesized by reaction of cis-Ru(dmso)(4)Cl(2) with [A-alpha-XW(9)O(34)](10-) in aqueous, acidic medium (pH 4.8). Tungsten-183 NMR of 1 leads to a spectrum with 11 peaks of equal intensity, indicating that the solid-state structure is preserved in solution. Electrochemistry studies revealed that 1 and 2 are stable in solution at least from pH 0 to 7, even in the presence of dioxygen. Their cyclic voltammetry patterns show mainly two two-electron reversible W-waves, those of the Si derivative 2 being located at slightly more negative potentials than those of the Ge derivative 1. The observed stability of 1 and 2 might be attributed to a stabilization of the Ru-center both by the strongly bound dmso ligands and the Keggin moiety. This stabilization drives the redox waves of Ru outside the accessible potential range. However, conditions were found to reveal, at least partially, the redox behavior of Ru in 1 and 2.     

Cyclic Ti9 keggin trimers with tetrahedral (PO4) or octahedral (TiO6) capping groups

We have synthesized the cyclic Ti 9 Keggin trimers [(alpha-Ti 3PW 9O 38) 3(PO 4)] (18-) ( 1) and [(alpha-Ti 3SiW 9O 37OH) 3(TiO 3(OH 2) 3)] (17-) ( 2), which are both composed of three (Ti 3XW 9O 37) units (X = P or Si) linked via three Ti-O-Ti bridges and a capping group, which is either tetrahedral PO 4 ( 1) or octahedral TiO 6 ( 2). Polyanions 1 and 2 were fully characterized in the solid state (IR, X-ray diffraction, thermogravimetric and elemental analyses) and in solution ( (31)P or (183)W NMR).     

Synthesis and structure of the pentacopper(II) substituted tungstosilicate [Cu5(OH)4(H2O)2(A-alpha-SiW9O33)2]10-

The dimeric, pentacopper(II) substituted tungstosilicate [Cu(5)(OH)(4)(H(2)O)(2)(A-alpha-SiW(9)O(33))(2)](10-) (1) has been synthesized in good yield using a one-pot procedure by reaction of Cu(2+) ions with the trilacunary precursor salt K(10)[A-alpha-SiW(9)O(34)]. The title polyanion represents the first polyoxotungstate substituted by 5 copper centers and the central copper-hydroxo-aqua fragment is completely unprecedented. In the course of the reaction, two [A-alpha-SiW(9)O(34)](10-) Keggin half-units have fused in an asymmetrical fashion resulting in the lacunary polyoxotungstate [Si(2)W(18)O(66)](16-). The vacancy in this species is stabilized by a magnetic cluster of five octahedrally coordinated Cu(2+) ions resulting in polyanion 1 with C(2v) symmetry.     

Interplay of cubic building blocks in (et6-arene)ruthenium-containing tungsten and molybdenum oxides

A series of molybdenum and tungsten organometallic oxides containing [Ru(arene)]2+ units (arene =p-cymene, C6Me6) was obtained by condensation of [[Ru(arene)Cl2]2] with oxomolybdates and oxotungstates in aqueous or nonaqueous solvents. The crystal structures of [[Ru(eta6-C6Me6]]4W4O16], [[Ru(eta6-p-MeC6H4iPr]]4W2O10], [[[Ru-(eta6-p-MeC6H4iPr)]2(mu-OH)3]2][[Ru(eta6-p-MeC6H4iPr)]2W8O28(OH)2[Ru(eta6-p-MeC6H4iPr)(H2O)]2], and [[Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) have been determined. While the windmill-type clusters [[Ru(eta6-arene)]4(MO3)4(mu3-O)4] (M = Mo, W; arene =p-MeC6H4iPr, C6Me6), the face-sharing double cubane-type cluster [[Ru(eta6-p-MeC6H4iPr)]4(WO2)2(mu3-O)4(mu4-O)2], and the dimeric cluster [[Ru(eta6-p-MeC6H4iPr)(WO3)3(mu3-O)3(mu3-OH)Ru(eta6-pMeC6H4iPr)(H2O)]2(mu-WO2)2]2- are based on cubane-like units, [(Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) are more properly described as lacunary Lindqvist-type polyoxoanions supporting three ruthenium centers. Precubane clusters [[Ru(eta6-arene)](MO3)2(mu-O)3(mu3-O)]6- are possible intermediates in the formation of these clusters. The cluster structures are retained in solution, except for [[Ru(eta6-p-MeC6H4iPr)]4Mo4O16], which isomerizes to the triple-cubane form.     

Structure,magnetism, and electrochemistry of the multinickel polyoxoanions [Ni6As3W24O94(H2O)2]17-, [Ni3Na(H2O)2(AsW9O34)2]11-, and [Ni4Mn2P3W24O94(H2O)2]17-

The three novel, multi-nickel-substituted heteropolytungstates [Ni(6)As(3)W(24)O(94)(H(2)O)(2)](17)(-) (1), [Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)](11)(-) (2), and [Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)](17)(-) (3) have been synthesized and characterized by IR, elemental analysis, electrochemistry, and magnetic studies. Single-crystal X-ray analysis was carried out on Na(16.5)Ni(0.25)[Ni(6)As(3)W(24)O(94)(H(2)O)(2)].54H(2)O, which crystallizes in the triclinic system, space group P1, with a = 17.450(4) A, b = 17.476(4) A, c = 22.232(4) A, alpha = 85.73(3) degrees, beta = 89.74(3) degrees, gamma = 84.33(3) degrees, and Z = 2, Na(11)[Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)].30.5H(2)O, which crystallizes in the triclinic system, space group P1, with a = 12.228(2) A, b = 16.743(3) A, c = 23.342(5) A, alpha = 78.50(3) degrees, beta = 80.69(3) degrees, gamma = 78.66(3) degrees, and Z = 2, and Na(17)[Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)].50.5H(2)O, which crystallizes in the monoclinic system, space group P2(1)/c, with a = 17.540(4) A, b = 22.303(5) A, c = 35.067(7) A, beta = 95.87(3) A, and Z = 4. Polyanion 1 consists of two B-alpha-(Ni(3)AsW(9)O(40)) Keggin moieties linked via a unique AsW(6)O(16) fragment, leading to a banana-shaped structure with C(2)(v)() symmetry. The mixed-metal tungstophosphate 3 is isostructural with 1. Polyanion 2 consists of two lacunary B-alpha-[AsW(9)O(34)](9)(-) Keggin moieties linked via three nickel(II) centers and a sodium ion. Electrochemical studies show that 1-3 exhibit a unique and reproducible voltammetric pattern and that all three compounds are stable in a large pH range. An investigation of the magnetic properties of 1-3 indicates that the exchange interactions within the trimetal clusters are ferromagnetic. However, for 1 and 3 intra- and intermolecular interactions between different trinuclear clusters are also present.     

Theoretical study of the relative stabilities of the alpha/beta3-[XW11O39](m-) lacunary polyoxometalates (X = P, Si)

A computational study of the relative stability of the monolacunary Keggin polyoxotungstates alpha and beta 3-[XW 11O 39] ( m- ) (X = P, m = 7; X = Si, m = 8) was performed. The influence of the nature of different grafted cations and of the central anion XO 4 ( n- ) on the relative stabilities of the lacunary isomers was analyzed. From these results, an interpretation of the structural difference in the metallic frameworks of alpha-[PW 11O 39{Ru(DMSO) 3(H 2O)}] (5-), alpha-[PW 11O 39{Ru(C 6H 6)(H 2O)}] (5-), and beta 3-[SiW 11O 39{Ru(DMSO) 3(H 2O)}] (6-) is proposed, and conclusions are drawn as to how to favor the formation of beta 3 derivatives in future syntheses.     

Aqueous speciation studies of europium(III) phosphotungstate

The incorporation of lanthanide ions into polyoxometalates may be a unique approach to generate new luminescent, magnetic, and catalytic functional materials. To realize these new applications of lanthanide polyoxometalates, it is imperative to understand the solution speciation chemistry and its impact on solid-state materials. In this study we find that the aqueous speciation of europium(III) and the trivacant polyoxometalate, PW9O34 9-, is a function of pH, countercation, and stoichiometry. For example, at low pH, the lacunary (PW11O39)7- predominates and the 1:1 Eu(PW11O39)4-, 2, forms. As the pH is increased, the 1:2 complex, Eu(PW11O39)2 11- species, 3, and (NH4)22[(Eu2PW10O38)4(W3O8(H2O)2(OH)4].44H2O, a Eu8 hydroxo/oxo cluster, 1, form. Countercations modulate this effect; large countercations, such as K+ and Cs+, promote the formation of species 3 and 1. Addition of Al(III) as a counterion results in low pH and formation of [Eu(H2O)3(alpha-2-P2W17O61)]2, 4, with Al(III) counterions bound to terminal W-O bonds. The four species observed in these speciation studies have been isolated, crystallized, and characterized by X-ray crystallography, solution multinuclear NMR spectroscopy, and other appropriate tech-niques. These species are 1, (NH4)22[(Eu2PW10O38)4(W3O8(H2O)2(OH)4].44H2O (P; a=20.2000(0), b=22.6951(6), c=25.3200(7) A; alpha=65.6760(10), beta=88.5240(10), gamma=86.0369(10) degrees; V=10550.0(5) A3; Z=2), 2, Al(H3O)[Eu(H2O)2PW11O34].20H2O (P, a=11.4280(23), b=11.5930(23), c=19.754(4) A; alpha=103.66(3), beta=95.29(3), gamma=102.31(3) degrees; V =2456.4(9) A3; Z=2), 3, Cs11Eu(PW11O34)2.28H2O (P; a=12.8663(14), b=19.8235(22), c=21.7060(23) A; alpha=114.57(0), beta=91.86(0), gamma=102.91(0) degrees ; V=4858.3(9) A3; Z=2), 4, Al2(H3O)8[Eu(H2O)3(alpha-2-P2W17O61)]2.29H2O (P; a=12.649(6), b=16.230(8), c=21.518(9) A; alpha=111.223(16), beta=94.182(18), gamma=107.581(17) degrees ; V=3842(3) A3; Z=1).     

Organometallic ruthenium(II) diamine anticancer complexes: arene-nucleobase stacking and stereospecific hydrogen-bonding in guanine adducts

Organometallic ruthenium(II) arene anticancer complexes of the type [(eta(6)-arene)Ru(II)(en)Cl][PF(6)] (en = ethylenediamine) specifically target guanine bases of DNA oligomers and form monofunctional adducts (Morris, R., et al. J. Med. Chem. 2001). We have determined the structures of monofunctional adducts of the "piano-stool" complexes [(eta(6)-Bip)Ru(II)(en)Cl][PF(6)] (1, Bip = biphenyl), [(eta(6)-THA)Ru(II)(en)Cl][PF(6)] (2, THA = 5,8,9,10-tetrahydroanthracene), and [(eta(6)-DHA)Ru(II)(en)Cl][PF(6)] (3, DHA = 9,10-dihydroanthracene) with guanine derivatives, in the solid state by X-ray crystallography, and in solution using 2D [(1)H,(1)H] NOESY and [(1)H,(15)N] HSQC NMR methods. Strong pi-pi arene-nucleobase stacking is present in the crystal structures of [(eta(6)-C(14)H(14))Ru(en)(9EtG-N7)][PF(6)](2).(MeOH) (6) and [(eta(6)-C(14)H(12))Ru(en)(9EtG-N7)][PF(6)](2).2(MeOH) (7) (9EtG = 9-ethylguanine). The anthracene outer ring (C) stacks over the purine base at distances of 3.45 A for 6 and 3.31 A for 7, with dihedral angles of 3.3 degrees and 3.1 degrees, respectively. In the crystal structure of [(eta(6)-biphenyl)Ru(en)(9EtG-N7)][PF(6)](2).(MeOH) (4), there is intermolecular stacking between the pendant phenyl ring and the purine six-membered ring at a distance of 4.0 A (dihedral angle 4.5 degrees). This stacking stabilizes a cyclic tetramer structure in the unit cell. The guanosine (Guo) adduct [(eta(6)-biphenyl)Ru(en)(Guo-N7)][PF(6)](2).3.75(H(2)O) (5) exhibits intramolecular stacking of the pendant phenyl ring with the purine five-membered ring (3.8 A, 23.8 degrees) and intermolecular stacking of the purine six-membered ring with an adjacent pendant phenyl ring (4.2 A, 23.0 degrees). These occur alternately giving a columnar-type structure. A syn orientation of arene and purine is present in the crystal structures 5, 6, and 7, while the orientation is anti for 4. However, in solution, a syn orientation predominates for all the biphenyl adducts 4, 5, and the guanosine 5'-monophosphate (5'-GMP) adduct 8 [(eta(6)-biphenyl)Ru(II)(en)(5'-GMP-N7)], as revealed by NMR NOE studies. The predominance of the syn orientation both in the solid state and in solution can be attributed to hydrophobic interactions between the arene and purine rings. There are significant reorientations and conformational changes of the arene ligands in [(eta(6)-arene)Ru(II)(en)(G-N7)] complexes in the solid state, with respect to those of the parent chloro-complexes [(eta(6)-arene)Ru(II)(en)Cl](+). The arene ligands have flexibility through rotation around the arene-Ru pi-bonds, propeller twisting for Bip, and hinge-bending for THA and DHA. Thus propeller twisting of Bip decreases by ca. 10 degrees so as to maximize intra- or intermolecular stacking with the purine ring, and stacking of THA and DHA with the purine is optimized when their tricyclic ring systems are bent by ca. 30 degrees, which involves increased bending of THA and a flattening of DHA. This flexibility makes simultaneous arene-base stacking and N7-covalent binding compatible. Strong stereospecific intramolecular H-bonding between an en NH proton oriented away from the arene (en NH(d)) and the C6 carbonyl of G (G O6) is present in the crystal structures of 4, 5, 6, and 7 (average N...O distance 2.8 A, N-H...O angle 163 degrees ). NMR studies of the 5'-GMP adduct 8 provided evidence that en NH(d) protons are involved in strong H-bonding with the 5'-phosphate and O6 of 5'-GMP. The strong H-bonding from G O6 to en NH(d) protons partly accounts for the high preference for binding of [(eta(6)-arene)Ru(II)en](2+) to G versus A (adenine). These studies suggest that simultaneous covalent coordination, intercalation, and stereospecific H-bonding can be incorporated into Ru(II) arene complexes to optimize their DNA recognition behavior, and as potential drug design features.     

The bis-phenyltin-substituted, lone-pair-containing tungstoarsenate [(C(6)h(5)Sn)(2)as(2)W(19)O(67)(H(2)O)](8)(-)

The bis-phenyltin-substituted, lone-pair-containing tungstoarsenate [(C(6)H(5)Sn)(2)As(2)W(19)O(67)(H(2)O)](8)(-) (1) has been synthesized and characterized by multinuclear NMR, IR, and elemental analysis. Single-crystal X-ray analysis was carried out on (NH(4))(7)Na[(C(6)H(5)Sn)(2)As(2)W(19)O(67)(H(2)O)].17.5H(2)O (NH(4)(-1), which crystallizes in the monoclinic system, space group P2(1)/c, with a = 18.3127(17) A, b = 24.403(2) A, c = 22.965(2) A, beta = 106.223(2) degrees, and Z = 4. Polyanion 1 consists of two B-alpha-(As(III)W(9)O(33)) Keggin moieties linked via a WO(H(2)O) fragment and two SnC(6)H(5) groups leading to a sandwich-type structure with nominal C(2)(v) symmetry. Polyanion 1 is stable in solution as indicated by the expected 6-line pattern (4:4:4:4:2:1) in (183)W NMR and the expected (119)Sn, (13)C, and (1)H NMR spectra. Synthesis of 1 was accomplished by reaction of C(6)H(5)SnCl(3) and K(14)[As(2)W(19)O(67)(H(2)O)] in a 2:1 molar ratio in aqueous acidic medium (pH 2). In the solid-state structure of NH(4)(-1, neighboring polyanions are weakly bound via W-O-Na bonds leading to chains which interact with each other via the phenyl rings resulting in a 2-D assembly.     

The antimony(III)-bridged heteropolyanion sandwich dimers [Sb(II3(A-α-XW9O34)2]11- (X = SiIV, GeIV and C-shaped double-sandwich [SbIII6O2(PW6O26)(A-α-PW9O34)2]15-

Interaction of potassium antimony(iii) tartrate hydrate K(2)(SbC(4)H(2)O(6))(2)·3H(2)O with the trilacunary Keggin derivatives [A-α-XW(9)O(34)](10-) (X = Si(IV), Ge(IV)) and [A-α-PW(9)O(34)](9-) in aqueous acidic medium (pH 4.8) resulted in three novel polyanions, [Sb(3)(A-α-XW(9)O(34))(2)](11-) (X = Si(IV) (1), Ge(IV) (2)) and [Sb(6)O(2)(A-PW(6)O(26))(A-α-PW(9)O(34))(2)](15-) (3), which were isolated as the hydrated potassium salts K(11)[Sb(3)(A-α-XW(9)O(34))(2)]·31H(2)O (X = Si(IV) (K-1), Ge(IV) (K-2)) and the mixed potassium-sodium salt K(14)Na[Sb(6)O(2)(A-PW(6)O(26))(A-α-PW(9)O(34))(2)]·61H(2)O (KNa-3) salts, respectively, and characterized by single-crystal X-ray diffraction, IR spectroscopy, as well as elemental and thermogravimetric analyses. The Sb(III)-containing polyanions 1-3 possess unique structural features, as they represent the first examples of sandwich-type POMs with trigonal-pyramidal Sb(III)O(3) linkers. The stability of 1-3 in aqueous media was investigated by multinuclear ((183)W, (31)P) NMR and UV-Vis spectroscopy.     

Sandwich-type phosphotungstates: structure,electrochemistry, and magnetism of the trinickel-substituted polyoxoanion [Ni(3)Na(H(2)O)(2)(PW(9)O(34))(2)](11-)

The novel nickel-substituted, dimeric phosphotungstate [Ni(3)Na(H(2)O)(2)(PW(9)O(34))(2)](11-) (1) has been synthesized and characterized by IR spectroscopy, elemental analysis, and electrochemistry. X-ray single-crystal analysis was carried out on Na(11)[Ni(3)Na(H(2)O)(2)(PW(9)O(34))(2)].21.25H(2)O, which crystallizes in the triclinic system, space group P1, with a = 12.2467(6) A, b = 16.6031(7) A, c = 22.4017(12) A, alpha = 73.9870(10) degrees, beta = 87.6060(10) degrees, gamma = 79.344(2) degrees, and Z = 2. The polyanion consists of two lacunary B-alpha-[PW(9)O(34)](9-) Keggin moieties linked via three nickel(II) centers and a sodium ion. The structure of 1 is composed of two fused Keggin fragments that represent different Baker-Figgis isomers (alpha- vs beta-type). Electrochemical studies show that 1 exhibits a stable and reproducible voltammetric pattern, with a first wave featuring a chemically reversible four-electron/four-proton process. An investigation of the magnetic properties indicates that the three nickel centers exhibit ferromagnetic exchange interaction.     

Hydrothermal and solid-state transformation of ruthenium-supported Keggin-type heteropolytungstates [XW11O39{Ru(II)(benzene)(H2O)}]n- (X = P (n = 5), Si (n = 6), Ge (n = 6)) to ruthenium-substituted Keggin-type heteropolytungstates

A new pathway for the preparation of mono-ruthenium (Ru)(iii)-substituted Keggin-type heteropolytungstates with an aqua ligand, [PW(11)O(39)Ru(iii)(H(2)O)](4-) (1a), [SiW(11)O(39)Ru(iii)(H(2)O)](5-) (1b) and [GeW(11)O(39)Ru(iii)(H(2)O)](5-) (1c), using [Ru(ii)(benzene)Cl(2)](2) as a Ru source was described. Compounds 1a-1c were prepared by reacting [XW(11)O(39)](n-) (X = P, Si and Ge) with [Ru(ii)(benzene)Cl(2)](2) under hydrothermal condition and were isolated as caesium salts. Ru(benzene)-supported heteropolytungstates, [PW(11)O(39){Ru(ii)(benzene)(H(2)O)}](5-) (2a), [SiW(11)O(39){Ru(ii)(benzene)(H(2)O)}](6-) (2b) and [GeW(11)O(39){Ru(ii)(benzene)(H(2)O)}](6-) (2c), were first produced in the reaction media, and then transformed to 1a, 1b and 1c, respectively, under hydrothermal conditions. Calcination of Ru(benzene)-supported heteropolytungstates, 2a, 2b and 2c, in the solid state produced mixtures of 1a, 1b and 1c with CO (carbon monoxide)-coordinated complexes, [PW(11)O(39)Ru(ii)(CO)](5-) (4a), [SiW(11)O(39)Ru(ii)(CO)](6-) (4b) and [GeW(11)O(39)Ru(ii)(CO)](6-) (4c), respectively. From comparison of their catalytic activities in water oxidation reaction, it was indicated that ruthenium should be incorporated in the heteropolytungstate in order to promote catalytic activity.     

Sandwich-type silicotungstates: structure and magnetic properties of the dimeric polyoxoanions[[SiM2W9O34(H2O)]2]12- (M = Mn2+, Cu2+, Zn2+)

The novel dimeric silicotungstates [[SiM2W9O34(H2O)]2]12- (M = Mn2+, Cu2+, Zn2+) have been synthesized and characterized by IR spectroscopy, elemental analysis, and magnetic measurements. X-ray single-crystal analyses were carried out on K4Na6Mn[[SiMn2W9O34(H2O)]2].33H2O (1), which crystallizes in the triclinic system, space group P1, with a = 12.2376(7) A, b = 13.6764(8) A, c = 15.6177(9) A, alpha = 70.2860(10) degrees, beta = 79.9150(10) degrees, gamma = 70.2760(10) degrees, and Z = 1; K3Na5[[SiCu2W9O34(H2O)]2].26H2O (2) crystallizes in the triclinic system, space group P1, with a = 11.4271(12) A, b = 12.5956(13) A, c = 15.3223(16) A, alpha = 80.456(2)degrees, beta = 76.383(2) degrees, gamma = 76.968(2) degrees, and Z = 1; K4Na6[[SiZn2W9O34(H2O)]2].34H2O (3) crystallizes also in the triclinic system, space group P1, with a = 12.2596(14) A, b = 13.2555(15) A, c = 16.2892(18) A, alpha = 96.431(2) degrees, beta = 100.944(2) degrees, gamma = 110.404(2) degrees, and Z = 1. The polyanions consist of two lacunary B-alpha-[SiW9O34]10- Keggin moieties linked via a rhomblike M4O16 (M = Mn, Cu, Zn) group leading to a sandwich-type structure. Magnetic measurements show that the central Mn4 unit in 1 exhibits antiferromagnetic (J = -1.77(5) cm(-1)) as well as weak ferromagnetic (J' = 0.08(2) cm(-1)) Mn-Mn exchange interactions. In 2 the Cu-Cu exchange interactions are antiferromagnetic (J = -0.10(2) cm(-1), J' = -0.29(2) cm(-1)).     

Structural study on highly oxidized states of a water oxidation complex [RuIII(bpy)2(H2O)]2(mu-O)4+ by ruthenium K-edge X-ray absorption fine structure spectroscopy

The oxidation-induced structural change of a water-oxidizing diruthenium complex, [(bpy)(2)(H(2)O)Ru(III)(micro-O)Ru(III)(OH(2))(bpy)(2)](4+) (bpy = 2,2'-bipyridine), was investigated by means of X-ray absorption spectroscopy. Ru K-edge XANES (X-ray absorption near-edge structure) spectra from the acidic solution and solid precipitates obtained by oxidation showed that the absorption edge shifts toward higher energy with a preedge feature slightly more enhanced than those of the lower oxidation states. This indicates that the higher oxidation state has a lower symmetry due to shortening of the Ru-O bonds that originated from the water ligands. The EXAFS (extended X-ray absorption fine structure) spectra were similar to those of the lower oxidation states, whose analysis revealed the existence of short Ru-O double bonds and an almost linear Ru-O-Ru angle (169 +/- 2 degrees ). Ab initio EXAFS simulations for several possible structural models suggest that the dimeric structure is maintained during the water oxidation reaction.     

An eta(6)-dienyne transition-metal complex

The ruthenium complexes, [(eta5-C5R5)Ru(CH3CN)3]PF6 (1-Cp*, R = Me; 1-Cp, R = H), underwent reaction with both 1-(2-chloro-1-methylvinyl)-2-pentynyl-(Z)-cyclopentene (6-Z) and 1-(2-chloro-1-methylvinyl)-2-pentynyl-(E)-cyclopentene (6-E) to give (eta5-C5R5)Ru[eta6-(5-chloro-4-methyl-6-propylindan)]PF6 (7-Cp*, R = Me; 7-Cp, R = H). In a similar fashion, reaction of 1-Cp and 1-Cp* with 1-isopropenyl-2-pent-1-ynylcyclopentene (8) led to the formation of (eta5-C5R5)Ru(eta6-4-methyl-6-propylindan)]PF6 (9-Cp*, R = Me; 9-Cp, R = H). The reaction of 1-Cp* with 8 at -60 degrees C in CDCl3 solution led to observation of the eta6-dienyne complex, (eta5-C5Me5)Ru[eta6-(1-isopropenyl-2-pent-1-ynylcyclopentene)]PF6 (10), by 1H NMR spectroscopy. Complexes 7-Cp and 10 were characterized by X-ray crystallographic analysis.     

铌取代型杂多钨酸盐的合成、表征、生物活性及晶体结构

合成了铌、过氧化铌取代的钨硅、钨锗杂多配合物M     

Organotin derivatives of alpha-[XIIIW9O33]9- (X = As,Sb) heteropolytungstates. Solution- and solid-state characterization of [[C6H5Sn)2O]2H(alpha-AsW9O33)2]9- and [(C6H5Sn)3Na3(alpha-SbW9O33)2]6-

The tris(phenyltin)-substituted tungstoantimonate(III) Cs6[(PhSn)3Na3(alpha-SbW9O33)2].20H2O (1) and the tetrakis-(phenyltin)-substituted tungstoarsenate(III) Na9[[(PhSn)2O]2H(alpha-AsW9O33)2].20H2O (2) have been prepared by reaction of phenyltin trichloride with Na9[alpha-SbW9O33].19.5H2O and Na9[alpha-AsW9O33].19.5H2O, respectively, in aqueous solution. The products were characterized by elemental analysis, X-ray crystallography, multinuclear NMR, and infrared spectroscopy. Crystals of 1 are monoclinic, space group P2(1)/n, with a = 13.7952(1) A, b = 22.3133(2) A, c = 34.4493(2) A, beta = 90.933(1) degrees, and Z = 4. Anion 1 has nominal D3h symmetry and contains three PhSn3+ groups and three sodium ions sandwiched between [alpha-SbW9O33]9- units. Crystals of 2 are triclinic, space group P1, with a = 15.272(6) A, b = 15.303(6) A, c = 16.760(7) A, alpha = 93.59(3) degrees, beta = 106.187(19) degrees, gamma = 112.23(3) degrees, and Z = 1. Anion 2 has nominal C2h symmetry and contains four PhSn3+ groups sandwiched between two [alpha-AsW9O33]9- units.     

Supramolecular assembly and solution properties of bis(bipyridyl)ruthenium(II) coordination complexes of aryl(2-pyridyl)methanones

A series of mono- and bis(2-pyridyl)-arylmethanone ligands were prepared by utilizing the reaction between either bromobenzonitrile or dicyanobenzene and 2-lithiopyridine in either a 1:1 or a 2:1 mol ratio, respectively. They react with [Ru(bpy)2(EtOH)2][PF6]2 to yield the new complexes [N,O-PhC(O)(2-py)Ru(bpy)2][PF6]2 (6), [p-N,O-BrC6H4C-(O)(2-py)Ru(bpy)2][PF6]2 (7), [m-N,O-BrC6H4C(O)(2-py)Ru(bpy)2][PF6]2 (8), [p-[N,O-C(O)(2-py)2Ru(bpy)2]2(C6H4)]-[PF6]4 (9), and [m-[N,O-C(O)(2-py)2Ru(bpy)2]2(C6H4)][PF6]4 (10). The solid state structures of 6 and 7 show that the octahedral cations are arranged in sinusoidal chains by pi-pi stacking and CH-pi interactions between bipyridyl groups. Substitution of bromine for hydrogen at the para position of the aryl group in 7 causes the aryl group to become involved in pi-pi stacking interactions that organize the chains into a sheet structure. The complicated 1H and 13C NMR spectra of the complexes have been fully assigned using 2D methods. The optical spectra show two absorption maxima near 434 and 564 nm due to MLCT transitions. The compounds were found to be nonluminescent. Electrochemical data acquired for CH3CN solutions of the bimetallic derivatives indicate that there is no electronic communication between metal centers mediated either through space or through ligand orbitals. Crystallographic information: 6.0.5CH3CN is monoclinic, C2/c, a = 24.3474(11) A, b = 13.7721(6) A, c = 21.3184(10) A, beta = 103.9920(10) degrees, Z = 8; 7 is monoclinic, P2(1)/c, a = 10.6639(11) A, b = 23.690(3) A, c = 13.7634(14) A, beta = 91.440(2) degrees, Z = 4.     

Synthesis and structural characterization of Sm(II) and Yb(II) complexes containing sterically demanding, chelating secondary phosphide ligands

Metathesis between [(Me3Si)2CH)(C6H4-2-OMe)P]K and SmI2(THF)2 in THF yields [([Me3Si]2CH)(C6H4-2-OMe)P)2Sm(DME)(THF)] (1), after recrystallization. A similar reaction between [(Me3Si)2CH)(C6H3-2-OMe-3-Me)P]K and SmI2(THF)2 yields [([Me3Si]2CH)(C6H3-2-OMe-3-Me)P)2Sm(DME)].Et2O (2), while reaction between [(Me3Si)2CH)(C6H4-2-CH2NMe2)P]K and either SmI2(THF)2 or YbI2 yields the five-coordinate complex [([Me3Si]2CH)(C6H4-2-CH2NMe2)P)2Sm(THF)] (3) or the solvent-free complex [([Me3Si]2CH)(C6H4-2-CH2NMe2)P)2Yb] (4), respectively. X-ray crystallography shows that complex 2 adopts a distorted cis octahedral geometry, while complex 1 adopts a distorted pentagonal bipyramidal geometry (1, triclinic, P1, a = 11.0625(9) A, b = 15.924(6) A, c = 17.2104(14) A, alpha = 72.327(2) degrees, beta = 83.934(2) degrees, gamma = 79.556(2) degrees, Z = 2; 2, monoclinic, P2(1), a = 13.176(4) A, b = 13.080(4) A, c = 14.546(4) A, beta = 95.363(6) degrees, Z = 2). Complex 3 crystallizes as monomers with a square pyramidal geometry at Sm and exhibits short contacts between Sm and the ipso-carbon atoms of the ligands (3, monoclinic, C2/c, a = 14.9880(17) A, b = 13.0528(15) A, c = 24.330(3) A, beta = 104.507(2) degrees, Z = 4). Whereas preliminary X-ray crystallographic data for 4 indicate a monomeric structure in the solid state, variable-temperature 1H, 13C(1H), 31P(1H), and 171Yb NMR spectroscopies suggest that 4 undergoes an unusual dynamic process in solution, which is ascribed to a monomer-dimer equilibrium in which exchange of the bridging and terminal phosphide groups may be frozen out at low temperature.