Dataset of polyoxometalate-assisted N-heterocyclic carbene gold(I) complexes.

The present paper is the Supplemental materials for our original paper entitled "highly active, homogeneous catalysis by polyoxometalate-assisted N-heterocyclic carbene gold(I) complexes for hydration of diphenylacetylene. The present article refers to the preparations of several monomeric, N-heterocyclic (NHC) carbene/carboxylate (RS-pyrrld)/gold(I) complexes, [Au(RS-pyrrld)(NHC)] (NHC = IMes (6), BIPr (7), IF3 (8), ItBu (9)), which were used for homogenous catalysis of the hydration reaction of diphenylacetylene to afford deoxybenzoin. The article also includes the preparations of the precursor complexes, [AuCl(NHC)] (NHC = IPr, IMes, BIPr, IF3, ItBu), and novel X-ray crystallography of the separately prepared [Au(IPr)(H2O)]3[α-PW12O40]·7Et2O (2), summary of crystal data of (2), and selected bond distances (Å) and angles (deg) of (2). Also presented are Cartesian coordinates of the optimized structures in the quantum-mechanical calculations.

Syntheses, Structures, and Antimicrobial Activities of Gold(I)- and Copper(I)- N-Heterocyclic Carbene (NHC) Complexes Derived from Basket-Shaped Dinuclear Ag(I)-NHC Complex.

Novel dinuclear gold(I)- and copper(I)- N-heterocyclic carbene (NHC, L-1a) complexes [M2(L-1a)](PF6)2 (M = AuI (Au-1·PF6) and M = CuI (Cu-1·PF6)) were synthesized by transmetalation of the dinuclear silver(I)-NHC complex [Ag2(L-1a)](PF6)2 (Ag-1·PF6) with [AuCl(Me2S)] or CuI in over 70% yield. These NHC complexes were characterized by CHN elemental analysis, Fourier transform infrared spectroscopy, thermogravimetry/differential thermal analysis, and solution (1H and 13C) NMR spectroscopy. X-ray crystallography revealed that Au-1·PF6 and Cu-1·PF6 are dinuclear molecules consisting of two linear intramolecular C-M-C bonds (M = AuI and CuI), one M···M interaction, and two metal atoms arranged in a T-shaped geometry; their molecular structures are very similar to the basket-shaped cage structure of the parent complex Ag-1·PF6. Because of the smaller ionic radius of copper(I), Cu-1·PF6 has the smallest upper space of the basket among the three complexes. Au-1·PF6 and Cu-1·PF6 were very stable in the solid state and in solution. They did not undergo nucleophilic reaction with thiols 2-mercaptoethanol and 2-benzimidazolethiol (Hbmt) at least for several hours, whereas Ag-1·PF6 did react, forming precipitates of silver(I) thiolate and the free ligand L-1a·PF6. The minimum inhibitory concentration values toward a panel of bacteria, yeasts, and molds were examined in a water-suspension system and a solution system containing dimethyl sulfoxide. The antimicrobial spectra of the three compounds were metal-dependent, and Au-1·PF6 showed the greatest activity toward Gram-positive bacteria.

Polyoxometalate-Assisted, One-Pot Synthesis of a Pentakis[(triphenylphosphane)gold]ammonium(2+) Cation Containing Regular Trigonal-Bipyramidal Geometries of Five Bonds to Nitrogen.

Novel intercluster compounds consisting of pentakis[(triphenylphosphane)gold]ammonium(2+) cation (1) and Keggin polyoxometalate (POM) anions, i.e., {[Au(PPh3)]5(µ5-N)}3[α-PM12O40]2 (1-PW for M = W; 1-PMo for M = Mo), were synthesized in 30-36% yield by one-pot reaction of the protonic acid form of the Keggin POMs, H3[α-PM12O40]·nH2O (n = 13 for M = W; n = 15 for M = Mo) with monomeric (triphenylphosphane)gold(I) carboxylate [Au(RS-pyrrld)(PPh3)] [RS-Hpyrrld = (RS)-2-pyrrolidone-5-carboxylic acid] in the presence of aqueous NH3 at a molar ratio of 2:15:x (x = 3 for 1-PW; x = 7.5 for 1-PMo). These compounds resulted from the nitrogen-centered phosphanegold(I) clusterization of in situ generated monomeric phosphanegold(I) units, [Au(PPh3)]+ or [Au(L)(PPh3)]+ (L = NH3 or solvent), during the carboxylate elimination of [Au(RS-pyrrld)(PPh3)] in the presence of the Keggin POMs and aqueous NH3. The products 1-PW and 1-PMo were characterized by elemental analysis, Fourier transform infrared, thermogravimetric and differential thermal analyses (TGA/DTA), X-ray crystallography, and solid-state cross-polarization magic-angle-spinning (CPMAS) (31P and 15N) and solution (31P{1H} and 1H) NMR spectroscopy. The lattice contained three independent {[Au(PPh3)]5(µ5-N)}2+ cations, of which two took regular trigonal-bipyramidal (TBP) geometries and the third took a distorted, square-pyramidal (SP) geometry. These geometries are in contrast to those reported by Schmidbaur's group for {[Au(PPh3)]5(µ5-N)}2+ cations as BF4 salts. Density functional theory and ONIOM calculations for {[(L3P)Au]nN}(n-3)+ (L = H or Ph; n = 4-6) showed that the pentacoordinate cluster is energetically most stable and its TBP structure is only 1.6 kcal mol-1 more stable than its SP structure, in accordance with the experimental facts.

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells-Dawson Polyoxometalate.

A novel compound containing a hexacalcium cluster cation, one carbonate anion, and one calcium cation assembled on a trimeric trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM), [{Ca6(CO3)(µ3-OH)(OH2)18}(P2W15Ti3O61)3Ca(OH2)3]19- (Ca7Ti9Trimer), was obtained as the Na7Ca6 salt (NaCa-Ca7Ti9Trimer) by the reaction of calcium chloride with the monomeric trititanium(IV)-substituted Wells-Dawson POM species "[P2W15Ti3O59(OH)3]9-" (Ti3Monomer). Ti3Monomer was generated in situ under basic conditions from the separately prepared tetrameric species with bridging Ti(OH2)3 groups and an encapsulated Cl- ion, [{P2W15Ti3O59(OH)3}4{µ3-Ti(H2O)3}4Cl]21- (Ti16Tetramer). The Na7Ca6 salt of Ca7Ti9Trimer was characterized by complete elemental analysis, thermogravimetric (TG) and differential thermal analyses (DTA), FTIR, single-crystal X-ray structure analysis, and solution 183W and 31P NMR spectroscopy. X-ray crystallography revealed that the [Ca6(CO3)(µ3-OH)(OH2)18]9+ cluster cation was composed of six calcium cations linked by one µ6-carbonato anion and one µ3-OH- anion. The cluster cation was assembled, together with one calcium ion, on a trimeric species composed of three tri-Ti(IV)-substituted Wells-Dawson subunits linked by Ti-O-Ti bonds. Ca7Ti9Trimer is an unprecedented POM species containing an alkaline-earth-metal cluster cation and is the first example of alkaline-earth-metal ions clustered around a titanium(IV)-substituted POM.

Crystal structure of catena-poly[silver(I)-µ-l-valinato-κ2N:O].

The reaction of Ag2O with l-valine (l-Hval, C5H11NO2) in a 1:2 molar ratio in water, followed by vapour diffusion, afforded a coordination polymer of the title compound, [Ag(C5H10NO2)] n , with N-Ag-O repeat units, which is classified as a type III silver(I) complex with amino acid ligands. The asymmetric unit consists of two independent units of [Ag(l-val)]. In the crystal, the polymeric chains run along [101], and neighbouring chains are linked via a weak Ag⋯Ag inter-action and N-H⋯O hydrogen bonds. The title complex exhibited anti-microbial activity against selected bacteria (Escherichia coli, Bacillus subtilis, Staphylococcous aureus and Psedomonas aeruginosa).

The effect of counteranions on the molecular structures of phosphanegold(i) cluster cations formed by polyoxometalate (POM)-mediated clusterization.

The effect of counteranions on the molecular structures of phosphanegold(i) cluster cations formed by polyoxometalate (POM)-mediated clusterization was investigated. A novel intercluster compound, [{(AuLCl)2(µ-OH)}2]3[α-PMo12O40]2·3EtOH (1-PMo12), was obtained as orange-yellow plate crystals in 12.0% yield from a 6 : 1 molar ratio reaction of the monomeric phosphanegold(i) carboxylato complex [Au(RS-pyrrld)(LCl)] (RS-Hpyrrld = RS-2-pyrrolidone-5-carboxylic acid; LCl = tris(4-chlorophenyl)phosphane) in CH2Cl2 with the free acid-form of Keggin polyoxometalate (POM), H3[α-PMo12O40]·14H2O. An EtOH/H2O (5 : 1, v/v) solvent mixture was used. The dimeric cation [{(AuLCl)2(µ-OH)}2](2+) in 1-PMo12 was in a parallel-edge arrangement that was formed by self-assembly through the inter-cationic aurophilic interactions of the µ-OH-bridged dinuclear phosphanegold(i) cation. The POM anion in 1-PMo12 was successfully exchanged with a smaller PF6(-) anion by the use of an anion-exchange resin. POM-free, colorless block crystals of [{(AuLCl)3(µ3-O)}2](PF6)2·4CH2Cl2 (2-PF6) were obtained by vapor diffusion in 14.1% yield. During the synthesis of 2-PF6, a compound with mixed counteranions (one POM and one PF6(-) anion), i.e. [{(AuLCl)4(µ4-O)}]2[α-PMo12O40]PF6 (3-PMo12PF6), was obtained in 66.4% yield. Both products were characterized by elemental analysis, TG/DTA, FT-IR, (31)P{(1)H} NMR, (1)H NMR, and X-ray crystallography. X-ray crystallography revealed that the countercation in 2-PF6 was the dimeric cation of the µ3-O-bridged tris{phosphanegold(i)} species, whereas that in 3-PMo12PF6 consisted of an unusual µ4-O-bridged tetragonal-pyramidal tetrakis{phosphanegold(i)} cation. Therefore, we concluded that the POM anion significantly contributed to the stabilization of these countercations (parallel-edged arrangement in 1-PMo12 and µ4-O-bridged tetragonal-pyramid in 3-PMo12PF6). Moreover, the previously reported yellow crystals of [{(AuLF)2(µ-OH)}2]3[PMo12O40]2·3EtOH (4-PMo12: LF = tris(4-fluoro phenyl)phosphane) were successfully converted to the POM-free crystalline OTf(-) salt [{(AuLF)2(µ-OH)}2](OTf)2·0.5Et2O (4-OTf) by the use of an anion-exchange resin. X-ray crystallography also revealed that the parallel-edge arrangement of the dimeric cation in 4-PMo12 was converted to the crossed-edge arrangement of that in 4-OTf. These results illustrate that the AuOPOM and hydrogen-bonding (C-HOPOM and O-HOPOM) interactions between the phosphanegold(i) cluster cation and the Keggin POM anion in the solid state significantly contribute to the structure, composition, and stability of the phosphane gold(i) cluster cations in 4-PMo12.

Synthesis, characterization, and structure-activity relationship of the antimicrobial activities of dinuclear N-heterocyclic carbene (NHC)-silver(I) complexes.

The three dinuclear silver(I) complexes of N-heterocyclic carbene (NHC) ligands, [Ag2(L-1a)](PF6)2·2CH3CN (Ag-1a), [Ag2(L-2)2](PF6)2·H2O (Ag-2), and [Ag2(L-4)2](PF6)2·2CH3CN (Ag-4), were synthesized by reactions of Ag2O with the corresponding PF6- salt of the NHC precursors indicated as H4L-1(PF6)4, H2L-2(PF6)2, and H2L-4(PF6)2. H4L-1(PF6)4, which is the precursor of ligand L-1, was formed as mixed crystals of two geometric isomers, i.e., H4L-1a(PF6)4 (major) and H4L-1b(PF6)4 (minor), each of which was not isolated as single species. Ag2O reacted with the mixed isomers of H4L-1(PF6)4 to give a single, pure crystalline silver(I) complex Ag-1a with one isomer (L-1a) as the major product. The molecular structures of the precursors and their silver(I) complexes were determined by X-ray crystallography. A mononuclear NHC-silver(I) complex (Ag-3) was prepared by the reaction of Ag2O with the precursor HL-3Cl. The silver(I) complexes and NHC precursors prepared here were characterized by CHN elemental analysis, FTIR, Thermogravimetry/Differential thermal analysis, X-ray crystallography and solution (1H and 13C) NMR spectroscopy. Organometallic silver(I) complexes Ag-1a, Ag-2, and Ag-4 were dinuclear C-Ag-C bonding complexes, whereas Ag-3 was a mononuclear C-Ag-Cl bonding complex. These complexes are highly soluble in organic solvents such as acetone, acetonitrile, and dimethyl sulfoxide, and light-stable in the solid-state and in solution over one year. The antimicrobial activities of four silver(I) complexes and their NHC precursors against selected bacteria, yeasts, and molds in water-suspension systems were evaluated via the minimum inhibitory concentration; the activities were strongly dependent on the molecular structures of the dinuclear silver(I) complexes, which suggests a structure-activity relationship.

Synthesis and Molecular Structure of a Water-Soluble, Dimeric Tri-Titanium(IV)-Substituted Wells-Dawson Polyoxometalate Containing Two Bridging (C5Me5)Rh2+ Groups.

A novel trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM)-based organometallic complex, i.e., a dimeric POM containing two bridging Cp*Rh(2+) groups (Cp* = C5Me5) or [{α-P2W15Ti3O60(OH)2}2(Cp*Rh)2](16-) (D-1) with Ci symmetry, was synthesized in an analytically pure form by a 1:2 -molar ratio reaction of the organometallic precursor [Cp*RhCl2]2 with the separately prepared, monomeric trititanium(IV)-substituted Wells-Dawson POM, "[P2W15Ti3O59(OH)3](9-)" (M-1). The crystalline sample (NaK-D-1) of the water-soluble, mixed sodium/potassium salt of D-1 was obtained in the 14.7% yield, which has been characterized by complete elemental analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solution ((183)W, (31)P, (1)H and (13)C{(1)H}) NMR spectroscopy. Single-crystal X-ray structure analysis revealed that the two species of the protonated Wells-Dawson subunits, "[P2W15Ti3O60(OH)2](10-)" were bridged by the two Cp*Rh(2+) groups, resulting in the an overall Ci symmetry. The Cp*Rh(2+) groups were linked to the two terminal oxygen atoms of the titanium(IV) sites and one edge-sharing oxygen atom of the surface Ti-O-Ti bond. The (183)W NMR of D-1 dissolved in D2O showed that its solution structure was represented as a dimeric POM with a formula of [{α-P2W15Ti3O60(OH)3}2{Cp*Rh(OH)}2](16-) (D-2) with Ci (or S2) symmetry. A trititanium(IV)-substituted Wells-Dawson POM-supported organometallic complex has never been reported so far, and thus D-1 in the solid state and D-2 in solution are the first example of this type of complex.

Two types of tetranuclear phosphanegold(I) cations as dimers of dinuclear units, [{(Au{P(p-RPh)3})2(µ-OH)}2]2+ (R = Me, F), synthesized by polyoxometalate-mediated clusterization.

Novel intercluster compounds [{(Au{P(p-RPh)3})2(µ-OH)}2]3[α-PM12O40]2·nEtOH (R = Me, M = W for 1; R = Me, M = Mo for 2; R = F, M = Mo for 3) were synthesized by the polyoxometalate (POM)-mediated clusterization of monomeric phosphanegold(I) complexes, and unequivocally characterized by elemental analysis, TG/DTA, FTIR, X-ray crystallography, and (1)H and (31)P{(1)H} NMR. In each cluster cation, two digold(I) units, {Au{P(p-RPh)3})2(µ-OH)}(+), dimerized to form the tetragold(I) cluster cation by interdimer aurophilic interactions, i.e., a dimer of dinuclear units, and these cations showed different forms of structural dimerization, i.e., a crossed-edge arrangement for 1 and 2 and a parallel-edge arrangement for 3, depending upon the substituent on the aryl group of triarylphosphanes. The dimerization of digold(I) cations was affected by not only the type of the POMs, but also the phosphane ligand of the monomeric phosphanegold(I) precursors.

Novel intercluster compound between a heptakis{triphenylphosphinegold(I)}dioxonium cation and an α-Keggin polyoxometalate anion.

A novel intercluster compound, [{{Au(PPh(3))}(4)(µ(4)-O)}{{Au(PPh(3))}(3)(µ(3)-O)}][α-PW(12)O(40)]·EtOH (1) constructed between a heptakis{triphenylphosphinegold(i)}dioxonium cation and an α-Keggin polyoxometalate (POM) is synthesized and unequivocally characterized by elemental analysis, TG/DTA, FTIR, X-ray crystallography, solid-state CPMAS (31)P NMR and solution ((1)H, (31)P{(1)H}) NMR. The heptagold(i) cluster was formed during the course of carboxylate elimination of a monomeric phosphinegold(i) carboxylate precursor, i.e., [Au((RS)-pyrrld)(PPh(3))] ((RS)-Hpyrrld = (RS)-2-pyrrolidone-5-carboxylic acid), in the presence of the sodium salt of an α-Keggin POM, Na(3)[α-PW(12)O(40)]·9H(2)O. Compound 1 was formed by ionic interaction between the heptagold(i) cluster cation and the α-Keggin POM anion. The heptagold(i) cluster unit was formed by four inter-cationic aurophilic interactions between the tetragold(i) cluster unit and trigold(i) cluster unit. The tetragold(i) cluster unit and trigold(i) cluster unit contained µ(4)-O and µ(3)-O atoms, respectively.

Syntheses, structures, and antimicrobial activities of remarkably light-stable and water-soluble silver complexes with amino acid derivatives, silver(I) N-acetylmethioninates.

Reaction of L- and DL-N-acetylmethionine (Hacmet) and Ag(2)O in water at ambient temperature afforded the remarkably light-stable silver complexes {[Ag(L-acmet)]}(n) (1) and {[Ag(2)(D-acmet)(L-acmet)]}(n) (2), respectively. The color of the solids and aqueous solutions of 1 and 2 did not change for more than 1 month under air without any shields. The light stability of these two silver(I) complexes is much higher than that of silver(I) methioninate {[Ag(2)(D-met)(L-met)]}(n) (3) (Hmet = methionine), silver(I) S-methyl-L-cysteinate {[Ag(L-mecys)]}(n) (4), and silver(I) L-cysteinate {[Ag(L-Hcys)]}(n) (5). X-ray crystallography of 1 obtained by vapor diffusion revealed that ladder-like coordination polymers with two O- and two S-donor atoms were formed. The acetyl group of acmet(-) prevents chelate formation of the ligand to the metal center, which is frequently observed in amino acid metal complexes, but allows for formation of hydrogen bonds between the ligands in the crystals of 1. These two silver(I) N-acetylmethioninates showed a wide spectrum of effective antimicrobial activities against gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and yeasts (Candida albicans and Saccharomyces cerevisiae), the effectiveness of which was comparable to that of water-soluble Ag-O bonding complexes.

Synthesis and structure of dawson polyoxometalate-based, multifunctional, inorganic-organic hybrid compounds: organogermyl complexes with one terminal functional group and organosilyl analogues with two terminal functional groups.

Four novel multifunctional polyoxometalate (POM)-based inorganic-organic hybrid compounds, [α(2)-P(2)W(17)O(61){(RGe)}](7-) (Ge-1, R(1) = HOOC(CH(2))(2(-)) and Ge-2, R(2) = H(2)C═CHCH(2(-))) and [α(2)-P(2)W(17)O(61){(RSi)(2)O}](6-) (Si-1, R(1) and Si-2, R(2)), were prepared by incorporating organic chains having terminal functional groups (carboxylic acid and allyl groups) into monolacunary site of Dawson polyoxoanion [α(2)-P(2)W(17)O(61)](10-). In these POMs, new modification of the terminal functional groups was attained by introducing organogermyl and organosilyl groups. Dimethylammonium salts of the organogermyl complexes, (Me(2)NH(2))(7)[α(2)-P(2)W(17)O(61)(R(1)Ge)]·H(2)O MeN-Ge-1 and (Me(2)NH(2))(7)[α(2)-P(2)W(17)O(61)(R(2)Ge)]·4H(2)O MeN-Ge-2, were obtained as analytically pure crystals, in 22.8% and 55.3% yields, respectively, by stoichiometric reactions of [α(2)-P(2)W(17)O(61)](10-) with separately prepared Cl(3)GeC(2)H(4)COOH in water, and H(2)C═CHCH(2)GeCl(3) in a solvent mixture of water/acetonitrile. Synthesis and X-ray structure analysis of the Dawson POM-based organogermyl complexes were first successful. Dimethylammonium salts of the corresponding organosilyl complexes, (Me(2)NH(2))(6)[α(2)-P(2)W(17)O(61){(R(1)Si)(2)O}]·4H(2)O MeN-Si-1 and (Me(2)NH(2))(6)[α(2)-P(2)W(17)O(61){(R(2)Si)(2)O}]·6H(2)O MeN-Si-2, were also obtained as analytically pure crystalline crystals, in 17.1% and 63.5% yields, respectively, by stoichiometric reactions of [α(2)-P(2)W(17)O(61)](10-) with NaOOC(CH(2))(2)Si(OH)(2)(ONa) and H(2)C═CHCH(2)Si(OEt)(3). These complexes were characterized by elemental analysis, thermogravimetric and differential thermal analyses (TG/DTA), FTIR, solid-state ((31)P) and solution ((31)P, (1)H, and (13)C) NMR, and X-ray crystallography.

Encapsulation of anion/cation in the central cavity of tetrameric polyoxometalate, composed of four trititanium(IV)-substituted α-Dawson subunits, initiated by protonation/deprotonation of the bridging oxygen atoms on the intramolecular surface.

Preparation and structural characterization of a novel polyoxometalate (POM), [(P(2)W(15)Ti(3)O(60.5))(4)(NH(4))](35-) 1, i.e., an encapsulated NH(4)(+) cation species in the central cavity of a tetramer (called the Dawson tetramer) constituted by trititanium(IV)-substituted α-Dawson POM substructure, are described. POM 1 was synthesized by several different methods and unequivocally characterized by complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR spectroscopy, solution ((15)N{(1)H}, (31)P, (183)W) NMR spectroscopy, and X-ray crystallography. First, POM 1 was synthesized by a reaction of NH(4)Cl in aqueous solution with a precursor, which was derived by thermal treatment of a monomeric triperoxotitanium(IV)-substituted Dawson POM, [α-1,2,3-P(2)W(15)(TiO(2))(3)O(56)(OH)(3)](9-) 2, for 3 h in an electric furnace at 200 °C. The encapsulated NH(4)(+) cation in 1 was confirmed by (15)N{(1)H} NMR measurement and X-ray crystallography. As another synthesis of 1, a direct exchange of the Cl(-) anion encapsulated in [{α-1,2,3-P(2)W(15)Ti(3)O(57.5)(OH)(3)}(4)Cl](25-) 3 with the NH(4)(+) cation was attained by neutralizing an aqueous solution containing 3 with the addition of aqueous NH(3) (the initial pH of ca. 2-2.5 was changed to 6.4), followed by adding NH(4)Cl. It has been clarified that the conditions as to whether the anion or the cation is encapsulated in the central cavity of the Dawson tetramer were significantly related to the protonation/deprotonation of the bridging oxygen atoms on the intramolecular surface, Ti-O-Ti/Ti-OH-Ti sites constituting the Dawson subunits.

Polyoxometalate (POM)-based, multi-functional, inorganic-organic, hybrid compounds: syntheses and molecular structures of silanol- and/or siloxane bond-containing species grafted on mono- and tri-lacunary Keggin POMs.

Using 3-mercaptopropyltrimethoxysilane (HS(CH2)3Si(OMe)3) as a silane-coupling agent (SCA), mono- and tri-lacunary Keggin polyoxometalate (POM)-based, multi-functional, inorganic-organic, hybrid compounds, (Et4N)3[α-PW11O39{(HS(CH2)3Si)2O}] EtN-1 (the 1 : 2 complex of a POM unit and organosilyl groups), (Bu4N)3[A-PW9O34(HS(CH2)3SiOH)3] BuN-2 (the 1 : 3 complex) and (Bu4N)3[A-α-PW9O34(HS(CH2)3SiO)3(Si(CH2)3SH)] BuN-3 (the 1 : 4 complex) were synthesized and unequivocally characterized by elemental analysis, thermogravimetric and differential thermal analyses (TG/DTA), FTIR, solid-state (²9Si and ³¹P) CPMAS NMR, solution (²9Si, ³¹P, ¹H and ¹³C) NMR, and X-ray crystallography. [Note: The moieties of their polyoxoanions are abbreviated simply as 1-3, respectively.] The X-ray molecular structures of EtN-1 and BuN-3 were determined. In EtN-1, two organic groups connected through a siloxane bond (-Si-O-Si- bond) were grafted on a mono-lacunary site of a Keggin POM, whereas in BuN-3 four organic groups connected through siloxane bonds were grafted on a tri-lacunary site of a Keggin POM. In BuN-2, three organic groups were grafted in the form of silanol (-SiOH) on a tri-lacunary site, i.e., in BuN-2 there was no siloxane bond. BuN-3 was synthesized as BuN-3a and BuN-3b by two methods, respectively; (1) BuN-3a was obtained by a 1 : 1 molar-ratio reaction of BuN-2 and an SCA in CH3CN, and (2) BuN-3b was prepared by a direct 1 : 4 molar-ratio reaction of a tri-lacunary Keggin POM and SCA in water-CH3CN. X-Ray crystallography revealed that BuN-3a is the same as BuN-3b. It is probable that BuN-2 is an intermediate in the formation of BuN-3. Terminal -SH groups in 1-3, as well as -OH groups in 2, can be utilized for immobilization of POMs and, also, as building blocks for the formation of novel hybrid compounds.

Intercluster compound between a tetrakis{triphenylphosphinegold(I)}oxonium cation and a keggin polyoxometalate (POM): formation during the course of carboxylate elimination of a monomeric triphenylphosphinegold(I) carboxylate in the presence of POMs.

The preparation and structural characterization of a novel intercluster compound, [{Au(PPh(3))}(4)(µ(4)-O)](3)[α-PW(12)O(40)](2)·4EtOH (1), constructed between a tetrakis{triphenylphosphinegold(I)}oxonium cation and a saturated α-Keggin polyoxometalate (POM) are described. The tetragold(I) cluster oxonium cation was formed during the course of carboxylate elimination of a monomeric phosphinegold(I) carboxylate complex, i.e., [Au((R,S)-pyrrld)(PPh(3))] [(R,S)-Hpyrrld = (R,S)-2-pyrrolidone-5-carboxylic acid], in the presence of the free acid form of a Keggin POM, H(3)[α-PW(12)O(40)]·7H(2)O. The liquid-liquid diffusion between the upper water/EtOH phase containing the Keggin POM and the lower CH(2)Cl(2) phase containing the monomeric gold(I) complex gave a pure crystalline sample of 1 in good yield (42.1%, 0.242 g scale). Complex 1 was formed by ionic interaction between the tetragold(I) cluster cation and the Keggin POM anion. As a matter of fact, the POM anion in 1 can be exchanged with the BF(4)(-) anion using an anion-exchange resin (Amberlyst A-27) in BF(4)(-) form. By using other Keggin POMs, such as H(4)[α-SiW(12)O(40)]·10H(2)O and H(3)[α-PMo(12)O(40)]·14H(2)O, the same tetragold(I) cluster cation was also formed, i.e., in the forms of [{Au(PPh(3))}(4)(µ(4)-O)](2)[α-SiW(12)O(40)]·2H(2)O (2) and [{Au(PPh(3))}(4)(µ(4)-O)](3)[α-PMo(12)O(40)](2)·3EtOH (3). Compounds 1-3, as dimethyl sulfoxide-soluble, EtOH- and Et(2)O-insoluble dark-yellowish white solids, were characterized by complete elemental analysis, thermogravimetric and differential thermal analyses, Fourier transform IR, X-ray crystallography, and solid-state (CPMAS (31)P and (29)Si) and solution ((31)P{(1)H} and (1)H) NMR spectroscopy. The molecular structures of 1 and 2 were successfully determined. The tetragold(I) cluster cation was composed of four PPh(3)Au(I) units bridged by a central µ(4)-oxygen atom in the geometry of a trigonal pyramid or distorted tetrahedron.

Synthesis and structure of dinuclear hafnium(IV) and zirconium(IV) complexes sandwiched between 2 mono-lacunary alpha-Keggin polyoxometalates.

The synthesis and characterization of two dinuclear HfIV and ZrIV complexes sandwiched between 2 mono-lacunary alpha-Keggin polyoxometalates (POMs), i.e., (Et2NH2)8[{alpha-PW11O39Hf(micro-OH)(H2O)}2].7H2O (Et2NH(2)-1) and (Et2NH2)8[{alpha-PW11O39Zr(micro-OH)(H2O)}2].7H2O (Et2NH(2)-2), are described. [Note: the moieties of their polyoxoanions are abbreviated simply as and , respectively.] A pair of HfIV- and ZrIV-containing POMs belonging to the same family were herein isolated as diethylammonium salts and were unambiguously characterized by complete elemental analysis, including sodium and oxygen analyses, TG/DTA, FT-IR, single-crystal X-ray structure analysis and solution (31P and 183W) NMR spectroscopy. Polyoxoanions 1 and 2 were isostructural with each other. The central [M2(micro-OH)2(H2O)2]6+ (M=Hf, Zr) cation unit was composed of 2 edge-sharing polyhedral M units, which were linked through 2 micro-OH groups and contained 1 water molecule coordinated to each metal center. Since the mono-lacunary Keggin POM acts as an oxygen-donor quadridentate ligand, the Hf and Zr centers are 7-coordinate. It should be noted that the present 2 Keggin 2:2-type compounds, Et2NH(2)-1 and Et2NH(2)-2, undergo a reversible conversion to Keggin 1:2-type complexes [M(alpha-PW11O39)2]10-, respectively, in solution under appropriate conditions. The synthesis of Et2NH(2)-1 and Et2NH(2)-2 is based on such an interconversion. The Zr compound Et2NH(2)-2 was rigorously compared with the 3 Zr POMs (OK-1-OK-3), recently reported by Kholdeeva's group: their POMs in a different protonation-state did not contain any coordinating water molecules.

Cyclic oligomer of oxide clusters through a siloxane bond. Synthesis and structure of reaction products of alpha2-mono-lacunary Dawson polyoxometalate with tetrachlorosilane and tetraethoxysilane.

The title compound with the formula (Me2NH2)13H5[{alpha2-P2W17O61(Si2O)}3(micro-O)3].39H2O Me2NH(2)-1 was obtained in 12.8% (0.258 g scale) yield by a 1:2 molar ratio reaction of alpha2-mono-lacunary Dawson polyoxometalate (POM) [alpha2-P2W17O61]10- with SiCl4 in water and unequivocally characterized by complete elemental analysis, TG/DTA, FTIR, (solution and solid-state) 31P NMR, solid-state 29Si NMR and X-ray crystallography. [Note: the moieties of the polyoxoanions in Me2NH(2)-1 and Me2NH(2)-2 are abbreviated simply as 1 and 2, respectively.] X-Ray crystallography revealed that the molecular structure of polyoxoanion 1 was a cyclic trimer consisting of three alpha2-mono-lacunary Dawson POM subunits constituted through intra- and intermolecular siloxane bonds. The compound resulted in an approximate Cs symmetry, but not the idealized C3v symmetry, because one Dawson unit was unequivalently incorporated into the cyclic framework. This compound is the first example of a siloxane-bonding cyclic trimer of POMs and its formation suggests that the oxygen atoms in the lacunary site of POM are reactive just like the surface oxygen atoms of silica. The formation of the cyclic trimer was also clarified by two control experiments: (1) the reaction of [alpha2-P2W17O61]10- with Si(OEt)4 under acidic conditions (pH 1), and (2) oligomerization under 6 M aqueous HCl acidic conditions (pH approximately 0) of the reactive monomer units (RMUs: tentatively assigned as "[alpha2-P2W17O61{O(SiOH)2}]6-"), derived from the cleavage of Ph-Si bonds by the thermal degradation of [alpha2-P2W17O61{O(SiPh)2}]6-. On the other hand, the reactions of alpha2-mono-lacunary Dawson POMs with GeX4 (X=OEt, Cl) gave the monomeric species of mono-germanium-substituted Dawson POM (Me2NH2)7[alpha2-P2W17O61(GeOH)].5H2O Me2NH(2)-2, which was characterized by CHN analysis, TG/DTA, FTIR, X-ray crystallography, and (solid-state and solution) 31P NMR spectroscopy. X-ray crystallography revealed that compound Me2NH(2)-2 was a monomeric species, but the Ge site per formula unit was not determined due to disorder of alpha-Dawson structure.

Sandwich-type Hf(IV) and Zr(IV)complexes composed of tri-lacunary Keggin polyoxometalates: structure of [M(3)(mu-OH)(3)(A-alpha-PW(9)O(34))(2)](9-) (M = Hf and Zr).

The syntheses and structures of hafnium(iv) and zirconium(iv) complexes with Keggin tri-lacunary polyoxometalates (POM) [A-alpha-PW(9)O(34)](9-), i.e., (Et(2)NH(2))(7)H(2)[Hf(3)(micro-OH)(3)(A-alpha-PW(9)O(34))(2)].11H(2)O (Et(2)NH(2)-) and (Et(2)NH(2))(7)H(2)[Zr(3)(micro-OH)(3)(A-alpha-PW(9)O(34))(2)].12H(2)O (Et(2)NH(2)-) are described. The two POMs, Et(2)NH(2)- and Et(2)NH(2)-, were obtained as analytically pure, colorless crystals in 30.0 and 40.9% yields, respectively, by 1:3-molar ratio reactions of [A-PW(9)O(34)](9-) with Hf(SO(4))(2) and Zr(SO(4))(2), respectively, in aqueous solutions at 80-90 degrees C, followed by refluxing. The two POMs were characterized by elemental analysis, TG/DTA, FTIR, solution ((31)P and (183)W) NMR and X-ray crystallography. X-Ray structure analysis of Et(2)NH(2)- revealed that in polyoxoanion , the three 6-coordinate prismatic Hf(IV) ions linked with the three bridging OH groups, i.e., the [Hf(3)(micro-OH)(3)](9+) cluster cation was sandwiched between two alpha-Keggin tri-lacunary POMs. The molecular structure of was isostructural with that of polyoxoanion in Et(2)NH(2)-. X-Ray crystallography also showed that the crude crystals of Et(2)NH(2)- and Et(2)NH(2)-, which were first formed without refluxing, contained the two isomeric crystalline species in a 7:3 ratio with the alpha,alpha- and alpha,beta-junctions of the two Keggin tri-lacunary POMs. These facts were also confirmed by (31)P NMR in D(2)O. By refluxing the solutions containing the crude crystals, only the alpha,alpha-isomers of Et(2)NH(2)- and Et(2)NH(2)- were finally isolated.

Syntheses, molecular structures and pH-dependent monomer-dimer equilibria of Dawson alpha2-monotitanium(IV)-substituted polyoxometalates.

The preparation and structural characterization of a novel, solid Brønsted acid based on Dawson alpha2-monotitanium(IV)-substituted polyoxometalates (POMs) are described. The free-acid form of the POM, i.e., 13H+-heteropolyacid with the formula H13[1b].55H2O DH-1 (1b = [(alpha2-P2W17TiO61)(alpha2-P2W17TiO61H)(mu-O)]13-), was prepared by passing an aqueous solution containing a potassium salt precursor, K14[1a].17H2O DK-1 (1a=[(alpha2-P2W17TiO61)2(mu-O)]14-), through a cation-exchange resin column. Compound DK-1 was obtained by a stoichiometric reaction of mono-lacunary Dawson POM [alpha2-P2W17O61]10- with Ti(SO4)2 in an aqueous solution. [Note: the abbreviations D, M, K and H stand for dimer, monomer, potassium salt and free-acid form, respectively.] Compounds DK-1 and DH-1 were characterized by using complete elemental analysis, thermogravimetric (TG) and differential thermal analysis (DTA), FTIR, solution (31P and 183W) NMR spectroscopy, pH-varied 31P NMR spectroscopy, solid-state 31P CPMAS NMR, X-ray crystallography and acidity measurements in an organic solvent with a Hammett indicator for DH-1. The monomeric form, K8[alpha2-P2W17TiO62]. 18H2O MK-1, was derived from DK-1. The molecular structure of 1b was composed of a dimer connected through one Ti-O-Ti bond between two alpha2-mono-Ti(IV)-substituted Dawson POM subunits. BVS (bond valence sum) calculation showed that one oxygen atom (O(60A)) in one of the two Dawson subunits was protonated, therefore the two subunits were unequivalent. On the other hand, the molecular structure of la was a Ti-O-Ti bonding dimer of two equivalent Dawson subunits. The pH-varied 31P NMR spectra of DK-1 and DH-1 in aqueous solutions showed that the monomer at pH 7.0, the dimer at pH 1.0-3.0, and the mono-protonated species of the dimer at pH 0.5 were the predominant species in the solutions. The Hammett acidity constant (H0) of DH-1 in CH3CN (-2.87) was estimated to be almost the same as that of homo-Dawson heteropolyacid H6[P2W18O62].17H2O(-2.77).

Synthesis, reaction and structure of a highly light-stable silver(I) cluster with an Ag4S4N4 core having a tridentate 4N-morpholyl 2-acetylpyridine thiosemicarbazone ligand: use of water-soluble silver(I) carboxylates as a silver(I) source.

A novel neutral tetrameric silver(I) cluster [Ag(mtsc)](4) was obtained from reactions of a tridentate (4)N-morpholyl 2-acetylpyridine thiosemicarbazone ligand (N'-[1-(2-pyridyl)ethylidene] morpholine-4-carbothiohydrazide, Hmtsc) and silver(I) sources containing Ag-O bonds (Ag(2)O, Ag(OAc), silver(I) 2-pyrrolidone-5-carboxylate (infinity){[Ag(Hpyrrld)](2)}, silver(I) 5-oxo-2-tetrahydrofurancarboxylate (infinity){[Ag(othf)](2)}, and silver(I) complexes with camphanic acid (infinity){[Ag(ca)]} and (infinity){[Ag(ca)(Hca)]}). The cluster was characterized by elemental analysis, TG/DTA, FTIR and single-crystal X-ray analysis in the solid state. The solution properties of the complexes were investigated using solution molecular weight measurement, ESI-MS and solution ((1)H, (13)C and (31)P) NMR spectroscopy. The obtained cluster is a novel example of a light-stable Ag(I) cluster with a tridentate thiosemicarbazone ligand and the second report of a crystal structure of a thiosemicarbazone silver(I) complex. The reaction of the tetramer with a large excess of PPh(3) gave dimeric complexes, namely, [Ag(micro(S)-mtsc)(PPh(3))](2) and [(PPh(3))(2)Ag(micro(S)-mtsc)(2)Ag]. The chloroform solution of the tetrameric complex showed modest and effective activities against selected bacteria (Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa) and yeasts (Candida albicans and Saccharomyces cerevisiae), respectively, but it did not inhibit the growth of any selected microorganisms in a water-suspension system.