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Article

Various Oxygen-Centered Phosphanegold(I) Cluster Cations Formed by Polyoxometalate (POM)-Mediated Clusterization: Effects of POMs and Phosphanes

by
Takuya Yoshida
1,2,3,
Yuta Yasuda
1,
Eri Nagashima
1,
Hidekazu Arai
1,
Satoshi Matsunaga
1 and
Kenji Nomiya
1,*
1
Department of Chemistry, Faculty of Science, Kanagawa University, Tsuchiya 2946, Hiratsuka, Kanagawa 259-1293, Japan
2
Research Center for Gold Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-0397, Japan
3
Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-0397, Japan
*
Author to whom correspondence should be addressed.
Inorganics 2014, 2(4), 660-673; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics2040660
Submission received: 13 October 2014 / Revised: 13 November 2014 / Accepted: 14 November 2014 / Published: 10 December 2014
(This article belongs to the Special Issue Frontiers in Gold Chemistry)
Browse Figures
Versions Notes

Abstract

:
Novel phosphanegold(I) cluster cations combined with polyoxometalate (POM) anions, i.e., intercluster compounds, [(Au{P(m-FPh)3})4(μ4-O)]2[{(Au{P(m-FPh)3})2(μ-OH)}2][α-PMo12O40]2·EtOH (1), [(Au{P(m-FPh)3})4(μ4-O)]2[α-SiMo12O40]·4H2O (2), [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiM12O40] (M = W (3), Mo (4)) and [{(Au{P(p-MePh)3})4(μ4-O)}{(Au{P(p-MePh)3})3(μ3-O)}][α-PW12O40] (5) were synthesized by POM-mediated clusterization, and unequivocally characterized by elemental analysis, TG/DTA, FT-IR, X-ray crystallography, solid-state CPMAS 31P NMR and solution (1H, 31P{1H}) NMR. Formation of the these gold(I) cluster cations was strongly dependent upon the charge density and acidity of the POMs, and the substituents and substituted positions on the aryl group of triarylphosphane ligands. These gold(I) cluster cations contained various bridged-oxygen atoms such as μ4-O, μ3-O and μ-OH groups.

Graphical Abstract

1. Introduction

Polyoxometalates (POMs) are discrete metal oxide clusters that are of current interest as soluble metal oxides and for their applications in catalysis, medicine and materials science [1,2,3,4,5,6]. The preparation of POM-based materials is therefore an active field of research. One of the intriguing aspects of POMs is that their combination with cluster cations or macrocations has resulted in the formation of various intercluster compounds that are interesting from the viewpoints of conducting research on ionic crystals, crystal engineering, structure, sorption properties and so on. In many compounds, POMs have been combined with the independently prepared metal cluster cations [7,8].
Recently, we unexpectedly found the clusterization of monomeric phosphanegold(I) units [Au(PR3)]+ during the course of carboxylate elimination of a monomeric phosphanegold(I) carboxylate [Au(RS-pyrrld)(PPh3)] (RS-Hpyrrld = RS-2-pyrrolidone-5-carboxylic acid. The previous representation of H2pyrrld was changed to Hpyrrld; thus, the formulation of [Au(RS-Hpyrrld)(PPh3)] used so far was also changed to [Au(RS-pyrrld)(PPh3)]) [9] in the presence of the free-acid form of the Keggin POM H3[α-PW12O40]·7H2O [10]. This reaction resulted in the formation of a tetrakis{triphenylphosphanegold(I)}oxonium cation [{Au(PPh3)}4(μ4-O)]2+ as a counterion of the POM. In addition, we also found that the reaction of [Au(RS-pyrrld)(PPh3)] with the sodium salt of the Keggin POM Na3[α-PW12O40]·9H2O gave a heptakis{triphenylphosphanegold(I)}dioxonium cation [{{Au(PPh3)}4(μ4-O)}{{Au(PPh3)}3(μ3-O)}]3+ as a counterion of the POM [11]. Also, the novel intercluster compounds [{(Au{P(p-RPh)3})2(μ-OH)}2]3[α-PM12O40]2·nEtOH (R = Me, M = W; R = Me, M = Mo; R = F, M = Mo) have been recently synthesized using the POM-mediated clusterization of monomeric para-substituted triarylphosphanegold(I) carboxylate [Au(RS-pyrrld){P(p-RPh)3}] (R = Me, F) [12]. The formation of such phosphanegold(I) cluster cations was strongly dependent upon the bulkiness, acidity and charge density of the POMs, and substituents on the aryl group of phosphane ligands. The POMs appeared to act as a template in the clusterization of monomeric phosphanegold(I) units generated from the elimination of the carboxylate ligands [13,14].
The field of element-centered gold clusters [E(AuL)n]m+ (E = group 13–17 elements) has been extensively studied by the groups of Schmidbaur [15,16] and Laguna [17]. The trigold(I) oxonium cluster cations [{Au(PR3)}3(μ3-O)]+ have been reported to exhibit different forms of structural dimerization depending upon the bulkiness of phosphane ligands, i.e., trigold(I) units are aggregated through crossed edges (R = Me) or parallel edges (R = Ph, etc.), resulting in the hexagold(I) dioxonium cluster cation as a dimer-of-trinuclear clusters [{{Au(PR3)}3(μ3-O)}2]2+ [18,19,20,21]. Dimerization of the gold(I) cluster cations also indicates that the aurophilic interaction is the driving force for the oligomerization of many phosphanegold(I) cluster cations in the solid state. In our reported dimer-of-dinuclear gold(I) cluster cations [{(Au{P(p-RPh)3})2(μ-OH)}2]2+, the two digold(I) units {(Au{P(p-RPh)3})2(μ-OH)}+ were dimerized by inter-cationic aurophilic interactions [12]. Also, the heptagold(I) dioxonium cluster cation [{{Au(PPh3)}4(μ4-O)}{{Au(PPh3)}3(μ3-O)}]3+ was regarded as an assembly of the tetragold(I) unit {{Au(PPh3)}4(μ4-O)}2+ and the trigold(I) unit {{Au(PPh3)}3(μ3-O)}+ induced by inter-cationic aurophilic interactions [11].
As continued work, we examined the POM-mediated clusterization of monomeric phosphanegold(I) units using the Keggin tungsto- and molybdo-POMs with heteroatoms P and Si, and the gold(I) carboxylate precursors with the X-substituted triarylphosphane ligands (X = m-F, m-Me and p-Me), [Au(RS-pyrrld){P(XPh)3}].
In this paper, we report the syntheses and characterization of several novel intercluster compounds, [(Au{P(m-FPh)3})4(μ4-O)]2[{(Au{P(m-FPh)3})2(μ-OH)}2][α-PMo12O40]2·EtOH (1), [(Au{P(m-FPh)3})4(μ4-O)]2[α-SiMo12O40]·4H2O (2), [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiW12O40] (3), [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiMo12O40] (4) and [{(Au{P(p-MePh)3})4(μ4-O)}{(Au{P(p-MePh)3})3(μ3-O)}][α-PW12O40] (5). These compounds were formed by reactions of the Keggin POMs having varied charge densities and different acidities with the phosphanegold(I) complexes containing varied substituents on the aryl group.

2. Results and Discussion

2.1. Synthesis and Compositional Characterization

The intercluster compounds between the phosphanegold(I) cluster cations and the Keggin POM anions were obtained as 1 in 35.9% (0.089 g scale) yield, as 2 in 4.64% (0.014 g scale) yield, as 3 in 71.4% (0.247 g scale) yield, as 4 in 46.7% (0.137 g scale) yield and as 5 in 26.0% (0.026 g scale) yield. These compounds were prepared by reactions between [Au(RS-pyrrld)(PR3)] (R = m-FPh (1, 2), m-MePh (3, 4) and p-MePh (5)) in CH2Cl2 and the Keggin POMs in mixed EtOH–H2O solvents, i.e., H3[α-PMo12O40]·14H2O (1), H4[α-SiMo12O40]·12H2O (2, 4), H4[α-SiW12O40]·10H2O (3) and Na3[α-PW12O40]·9H2O (5). Their crystallizations were carried out by slow evaporation or liquid-liquid diffusion at room temperature. Characterization was performed by X-ray crystallography, CHN elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared (FT-IR), solid-state cross-polarization magic-angle-spinning (CPMAS) 31P nuclear magnetic resonance (NMR) spectroscopy and solution (1H, 31P{1H}) NMR spectroscopy. The presence of any solvated molecules was confirmed by CHN elemental analysis, TG/DTA measurements under atmospheric conditions (Figures S1–S5), and 1H NMR for solvated ethanol molecules.
All gold(I) cluster cations in these intercluster compounds 1–5 contained bridged-oxygen atoms such as μ4-O, μ3-O and μ-OH groups, which were originated from water contained in the reaction system and/or the hydrated water molecules of the POMs.
The solid-state FT-IR spectra of 1–5 showed the characteristic vibrational bands on the basis of coordinating PR3 ligands (Figures S6–S10). The FT-IR spectra also showed prominent vibrational bands owing to the α-Keggin molybdo- and tungsto-POMs [22]. In these spectra, the carbonyl vibrational bands of the anionic RS-pyrrld ligand in the [Au(RS-pyrrld)(PR3)] precursors disappeared, showing that the carboxylate ligand was eliminated. Elimination of the carboxylate ligand was also confirmed by 1H NMR in DMSO-d6. The carboxylate plays a role of only the leaving group. In fact, not only pyrrolidone carboxylate, but also other carboxylates such as 5-oxotetrahydrofran-2-carboxylate and acetylglycinate can serve as the leaving groups in the formation of the tetragold(I) clusters in the presence of POMs [10].
Table
Table 1. Crystallographic data for 1–5.
Table 1. Crystallographic data for 1–5.
Parameters12345
FormulaC216H146Au12F36-Mo24O84P14C144H104Au8F24-Mo12O46P8SiC168H168Au8O46-P8SiW12C168H168Au8Mo12-O46P8SiC147H147Au7O42-P8W12
Formula weight9869.076029.136980.815925.896418.37
Color, shapeOrange-yellow, rodYellow, blockPale-yellow, blockYellow, blockColorless, plate
Crystal systemTriclinicTriclinicRhombohedralRhombohedralTriclinic
Space groupP-1P-1R-3R-3P-1
T/K100120120100100
a/Å16.191(2)16.296(3)20.478(3)20.3813(7)17.7243(11)
b/Å29.165(4)16.357(3) 17.8341(10)
c/Å35.365(4)16.854(3)36.726(7)36.679(2)31.7570(18)
α/°99.801(2)77.37(3) 104.8260(10)
β/°99.153(2)75.89(3) 92.640(2)
γ/°104.963(2)80.58(3)120120109.6850(10)
V/Å315533(3)4222.3(15)13337(4)13195.2(11)9040.0(9)
Z21332
Dcalc/g cm−32.1102.3712.6072.2372.358
F00092082822959484425852
GOF1.0271.0661.3111.0741.373
R1 (I > 2.00 σ(I))0.07230.09150.05470.03760.1466
R (all data)0.10770.10420.05580.03900.2417
wR2 (all data)0.17530.25020.12170.08620.4614

2.2. Molecular Structures of 1–5

Crystal data of 1–5 were given in Table 1. Bond lengths (Å) and angles (°) for 1–5 were shown in Supplementary Information (Tables S1–S5).
Single-crystal X-ray analysis revealed that 1 crystallizes in the Triclinic P-1 space group, and is composed of two tetragold(I) cluster cations [(Au{P(m-FPh)3})4(μ4-O)]2+ and one dimer-of-dinuclear gold(I) cluster cation [{(Au{P(m-FPh)3})2(μ-OH)}2]2+, and two Keggin POM anions [α-PMo12O40]3− as counterions (Figure 1a).
Inorganics 02 00660 g001 1024
Figure 1. (a) Molecular structure of 1; (b) The partial structure of the tetragold(I) cluster cation moiety; (c) The partial structure of the dimer-of-dinuclear gold(I) cluster cation moiety; (d) The interactions among the tetragold(I) cluster cations, dimer-of-dinuclear gold(I) cluster cation and Keggin polyoxometalate (POM) anions.
Figure 1. (a) Molecular structure of 1; (b) The partial structure of the tetragold(I) cluster cation moiety; (c) The partial structure of the dimer-of-dinuclear gold(I) cluster cation moiety; (d) The interactions among the tetragold(I) cluster cations, dimer-of-dinuclear gold(I) cluster cation and Keggin polyoxometalate (POM) anions.
Inorganics 02 00660 g001
The two tetragold(I) cluster cations [(Au{P(m-FPh)3})4(μ4-O)]2+ adopt trigonal-pyramidal structures composed of three short edges associated with (Au1, Au2, Au3, Au4) atoms and (Au9, Au10, Au11, Au12) atoms, respectively (Au1–Au2: 2.9513 Å, Au1–Au3: 2.8978 Å, Au1–Au4: 2.8582 Å; Au9–Au10: 2.9293 Å, Au9–Au11: 2.8719 Å, Au9–Au12: 3.0815 Å), and a triangular plane of (Au2, Au3, Au4) atoms and (Au10, Au11, Au12) atoms, respectively, with longer edge lengths (Au2–Au3: 3.650 Å, Au2–Au4: 3.655 Å, Au3–Au4: 3.536 Å; Au10–Au11: 3.568 Å, Au10–Au12: 3.528 Å, Au11–Au12: 3.717 Å) (Figure 1b). The bridged-oxygen atoms (μ4-O) were placed within the basal plane composed of (Au2, Au3, Au4) atoms and (Au10, Au11, Au12) atoms, respectively (Au2–O1–Au3: 123.6°, Au2–O1–Au4: 120.0°, Au3–O1–Au4: 116.1°; Au10–O2–Au11: 117.4°, Au10–O2–Au12: 116.2°, Au11–O2–Au12: 126.4°), resulting in a point group of C3v for the tetragold(I) cluster cations. The distorted tetragold(I) cluster cations in 1 are similar to that of the previously reported tetragold(I) cluster cation [{Au(PPh3)}4(μ4-O)]2+ as the counterion of the POM [10,13].
The dimer-of-dinuclear gold(I) cluster cation in 1 can be regarded as the dimerization of digold(I) units {(Au{P(m-FPh)3})2(μ-OH)}+. The digold(I) unit consists of two monomer subunits (Au{P(m-FPh)3})+ linked by a μ-OH group and is triangular in shape. Two digold(I) units dimerize to form the dimer-of-dinuclear gold(I) cluster cation [{(Au{P(m-FPh)3})2(μ-OH)}2]2+ in a parallel-edge arrangement by inter-cationic aurophilic interactions (Au5–Au7: 3.2921 Å, Au6–Au8: 3.3454 Å) (Figure 1c). The dimer-of-dinuclear gold(I) cluster cation of a parallel-edge arrangement in 1 is similar to that of the previously reported dimer-of-dinuclear gold(I) cluster cation [{(Au{P(p-FPh)3})2(μ-OH)}2]2+ with [α-PMo12O40]3− [12].
The five gold(I) atoms Au3, Au4, Au10, Au11 and Au12 in the tetragold(I) cluster cation moiety interact with the terminal oxygen atoms and OMo2 oxygen atoms of edge-shared MoO6 octahedra of the Keggin POMs (Au3–O6: 2.943 Å, Au4–O5: 3.143 Å, Au4–O6: 3.136 Å, Au4–O17: 3.087 Å, Au10–O45: 3.179 Å, Au10–O47: 3.143 Å, Au11–O45: 3.112 Å, Au11–O46: 3.023 Å, Au11–O57: 3.047 Å, Au12–O47: 3.123 Å). The two gold(I) atoms Au5 and Au8 in the dimer-of-dinuclear gold(I) cluster cation moiety interact with the OMo2 oxygen atoms of edge-shared MoO6 octahedra of the Keggin POMs (Au5–O37: 2.945 Å, Au8–O75: 2.853 Å), and the short distances between dimer-of-dinuclear gold(I) cluster cation and Keggin POMs indicate the existence of a hydrogen bonding (O3–O28: 3.021 Å, O4–O65: 3.043 Å) (Figure 1d). The meta-substituted triarylphosphane ligand was few influence for the POM-mediated clusterization of monomeric phosphanegold(I) units.
Single-crystal X-ray analysis revealed that 2 crystallizes in the Triclinic P-1 space group, and is composed of two tetragold(I) cluster cations [(Au{P(m-FPh)3})4(μ4-O)]2+ and one Keggin POM anion [α-SiMo12O40]4− as counterion (Figure S11a). Single-crystal X-ray analysis also revealed that 3 and 4 crystallize in the Rhombohedral R-3 space group, respectively, and are composed of two tetragold(I) cluster cations, [(Au{P(m-MePh)3})4(μ4-O)]2+, and one Keggin POM anion [α-SiW12O40]4− for 3 (Figure S12) and [α-SiMo12O40]4− for 4 as counterions.
The tetragold(I) cluster cation [(Au{P(m-FPh)3})4(μ4-O)]2+ of 2 was very similar to that of 1 (C3v symmetry) (Figure S11b). The three gold(I) atoms Au2, Au3 and Au4 in the tetragold(I) cluster cation interact with the OMo2 oxygen atoms of edge-shared MoO6 octahedra and terminal oxygen atoms of the Keggin POM (Au2–O4: 3.094 Å, Au2–O9: 3.070 Å, Au3–O3: 3.139 Å, Au3–O8: 3.021 Å, Au4–O10: 2.916 Å). The tetragold(I) cluster cations [(Au{P(m-MePh)3})4(μ4-O)]2+ of 3 and 4 adopt trigonal-pyramidal structures (C3v symmetry) due to interactions with the Keggin POMs (Au2–O3: 3.178 Å, Au2–O7: 2.994 Å for 3; Au2–O2: 3.144 Å, Au2–O4: 2.929 Å for 4). The Keggin POM anion was disordered. Compound 4 is isostructural with 3, with the different metal atom (W vs. Mo) in the Keggin POM anion.
Single-crystal X-ray analysis revealed that 5 crystallizes in the Triclinic P-1 space group, and is composed of a heptagold(I) cluster cation [{(Au{P(p-MePh)3})4(μ4-O)}{(Au{P(p-MePh)3})3(μ3-O)}]3+ and one Keggin POM anion [α-PW12O40]3− as counterion (Figure 2a). However, the crystals of 5 were not suitable for X-ray analysis. Although the existence of the heptagold(I) cluster cation was confirmed, the quality of the crystal data was poor (Table 1).
Inorganics 02 00660 g002 1024
Figure 2. (a) Molecular structure of 5; (b) The partial structure of the heptagold(I) cluster cation.
Figure 2. (a) Molecular structure of 5; (b) The partial structure of the heptagold(I) cluster cation.
Inorganics 02 00660 g002
The heptagold(I) cluster cation was composed of the tetragold(I) cluster cation and trigold(I) cluster cation (Figure 2b). Two gold(I) cluster cations were linked by the one inter-cationic aurophilic interaction (Au4–Au5: 3.034 Å). The aurophilic interaction is longer than the Au–Au separation of metallic gold (2.88 Å) [23], but shorter than twice the van der Waals radius for gold (3.32 Å) [24]. In comparison with the previously reported heptagold(I) cluster cation [{{Au(PPh3)}4(μ4-O)}{{Au(PPh3)}3(μ3-O)}]3+ [11], the heptagold(I) cluster cation in 5 has a similar structure, but the number of inter-cationic aurophilic interaction was decreased. This different coupled structure is produced by steric effects of the methyl groups in the para-substituted triarylphosphane ligands. On the other hand, the bridged-oxygen–oxygen distance (O1–O2: 2.830 Å) in the heptagold(I) cluster cation in 5 is shorter than that (3.096 Å) of the previously reported heptagold(I) cluster cation. This oxygen–oxygen distance is also shorter than twice the van der Waals radius for oxygen (3.04 Å) [24]. The tetragold(I) cluster moiety had a distorted tetrahedron structure due to four intra-cationic aurophilic interactions (Au1–Au2: 3.308 Å, Au1–Au3: 3.112 Å, Au1–Au4: 3.064 Å, Au3–Au4: 3.111 Å). The encapsulated oxygen atom (μ4-O) was placed within the distorted tetrahedron (Au2–O1–Au3: 126.9°, Au2–O1–Au4: 129.4°, Au3–O1–Au4: 92.4°; total 348.7°). The trigold(I) cluster moiety composed of two intra-cationic aurophilic interactions (Au5–Au7: 3.199 Å, Au6–Au7: 3.078 Å) and one long Au–Au edge (Au5–Au6: 3.606 Å) formed a triangular plane of the (Au5, Au6, Au7) atoms. The bridged-oxygen atom (μ3-O) was placed out-of-plane consisting a triangular plane of the three gold(I) atoms (Au5–O2–Au6: 127.9°, Au5–O2–Au7: 104.0°, Au6–O2–Au7: 98.2°; total 330.1°). Probably, the heptagold(I) cluster cation would be formed by the clusterization of monomeric triarylphosphanegold(I) units [Au(PR3)]+ with smaller steric effects in the presence of the less-acidic POM, i.e., Na3[α-PW12O40]·9H2O [11].

2.3. Solid-State CPMAS 31P and Solution 31P{1H} NMR

The solid-state CPMAS 31P and solution 31P{1H} NMR in DMSO-d6 signals of 1–5 are listed in Table 2. The solid-state CPMAS 31P NMR of 1 observed two broad signals at −3.4 and 24.4 ppm. The signal at −3.4 ppm is assignable to the heteroatom phosphorus in the Keggin molybdo-POM anion, and the signal at 24.4 ppm is assignable to the overlapped signals of the tetragold(I) cluster cations and the dimer-of-dinuclear gold(I) cluster cation. The solid-state CPMAS 31P NMR of 2, 3 and 4 showed two broad signals at 19.6 and 24.4 ppm for 2, 18.3 and 28.5 ppm for 3, 17.4 and 27.7 ppm for 4 originating from the inequivalent phosphane groups. The three signals at 19.6, 18.3 and 17.4 ppm are assignable to one apical phosphane group, respectively, and the other three signals at 24.4, 28.5 and 27.7 ppm are assignable to the three basal phosphane groups in the trigonal-pyramidal structure, respectively [10,13]. The solid-state CPMAS 31P NMR of 5 showed two broad signals at −14.6 and 23.1 ppm due to the Keggin tungsto-POM anion and phosphane groups of the heptagold(I) cluster cation, respectively. Although all phosphane groups of the heptagold(I) cluster cation are inequivalent as shown in X-ray analysis, their signals were observed as one broad peak at 23.1 ppm.
Table
Table 2. Solid-state cross-polarization magic-angle-spinning (CPMAS) 31P and solution 31P{1H} nuclear magnetic resonance (NMR) in DMSO-d6 signals (ppm) of 1–5.
Table 2. Solid-state cross-polarization magic-angle-spinning (CPMAS) 31P and solution 31P{1H} nuclear magnetic resonance (NMR) in DMSO-d6 signals (ppm) of 1–5.
CompoundSolid-State CPMAS 31PSolution 31P{1H}
1−3.4, 24.4−3.23, 26.31 (main), −0.40, 43.57 (minor)
219.6, 24.425.67 (main), 43.38 (minor)
318.3, 28.5insoluble
417.4, 27.7insoluble
5−14.6, 23.1−14.88, 22.39
The solution 31P{1H} NMR signals of 1, 2 and 5 in DMSO-d6 were observed as major sharp signals at 26.31, 25.67 and 22.39 ppm, respectively. These signals were shifted to a higher field from the monomeric phosphanegold(I) precursors (29.20 and 25.35 ppm), respectively. In general, the 31P{1H} NMR signals of oxygen-centered phosphanegold(I) clusters are observed in the higher field in comparison with those of the monomeric phosphanegold(I) precursors [10,11,12]. The peak at −3.23 ppm for 1 and −14.88 ppm for 5 are assignable to the heteroatom phosphorus in the Keggin POMs (M = Mo, W). Because Keggin molybdo-POMs are unstable in DMSO, the minor signals at −0.40, 43.57 ppm of 1 and 43.38 ppm of 2 are assignable to the decomposition species. Because 3 and 4 are insoluble in any solvents, the solution 31P{1H} NMR data of 3 and 4 were not obtained.

3. Experimental Section

3.1. Materials

The following reactants were used as received: EtOH, CH2Cl2, Et2O (all from Wako, Osaka, Japan), and DMSO-d6 (Isotec, Miamisburg, OH, USA). With respect to the α-Keggin POMs, H3[α-PMo12O40]·14H2O, H4[α-SiMo12O40]·12H2O, H4[α-SiW12O40]·10H2O and Na3[α-PW12O40]·9H2O were prepared according to the ether extraction method [25] and the literatures [26,27], and identified by FT-IR, TG/DTA and solution (29Si, 31P, 183W) NMR spectroscopy. The [Au(RS-pyrrld){P(m-XPh)3}] (X = F, Me) and [Au(RS-pyrrld){P(p-MePh)3}] precursor complexes were synthesized according to the reported methods using P(m-XPh)3 (X = F, Me) or P(p-MePh)3 [9,12], and characterized by CHN elemental analysis, FT-IR, TG/DTA and solution (1H, 13C{1H}, 31P{1H}) NMR spectroscopy.

3.2. Instrumentation and Analytical Procedures

CHN elemental analyses were carried out with a Perkin-Elmer (Waltham, MA, USA) 2400 CHNS Elemental Analyzer II (Kanagawa University, Kanagawa, Japan). IR spectra were recorded on a Jasco (Tokyo, Japan) 4100 FT-IR spectrometer in KBr disks at room temperature. TG/DTA were acquired using a Rigaku (Tokyo, Japan) Thermo Plus 2 series TG 8120 instrument. 1H NMR (500.00 MHz) and 31P{1H} NMR (202.00 MHz) spectra in a DMSO-d6 solution were recorded in 5-mm-outer-diameter tubes on a JEOL (Tokyo, Japan) JNM-ECP 500 FT-NMR spectrometer with a JEOL (Tokyo, Japan) ECP-500 NMR data processing system. The 1H NMR spectra were referenced to an internal standard of tetramethylsilane (SiMe4). The 31P{1H} NMR spectra were referenced to an external standard of 25% H3PO4 in H2O in a sealed capillary. The 31P{1H} NMR data with the usual 85% H3PO4 reference are shifted to +0.544 ppm from our data. Solid-state CPMAS 31P NMR (121.00 MHz) spectra were recorded in 6-mm-outer-diameter rotors on a JEOL JNM-ECP 300 FT-NMR spectrometer with a JEOL ECP-300 NMR data processing system. The spectra were referenced to an external standard of (NH4)2HPO4 (δ 1.60).

3.3. Syntheses

[(Au{P(m-FPh)3})4(μ4-O)]2[{(Au{P(m-FPh)3})2(μ-OH)}2][α-PMo12O40]2·EtOH (1): A solution of [Au(RS-pyrrld){P(m-FPh)3}] (0.192 g, 0.300 mmol) dissolved in 25 mL of CH2Cl2 was slowly added to a yellow clear solution of H3[α-PMo12O40]·14H2O (0.104 g, 0.050 mmol) dissolved in 15 mL of an EtOH–H2O (5:1, v/v) mixed solvent. After stirring for 1 h at room temperature, the reaction solution was filtered through a folded filter paper (Whatman, Maidstone, UK, No. 5). The resulting yellow clear solution was slowly evaporated at room temperature in the dark. After 7 days, the orange yellow rod crystals were formed, and collected on a membrane filter (JG 0.2 μm), washed with EtOH (20 mL × 2) and Et2O (20 mL × 2), and dried in vacuo for 2 h. Yield: 0.089 g (35.9%). The crystalline samples were soluble in DMSO, but insoluble in H2O, EtOH and Et2O. Calcd. for C218H152O85F36P14Mo24Au12 or [(Au{P(m-FPh)3})4(μ4-O)]2[{(Au{P(m-FPh)3})2(μ-OH)}2][α-PMo12O40]2·EtOH: C, 26.41; H, 1.55%. Found: C, 26.35; H, 1.15%. TG/DTA under atmospheric conditions: a weight loss of 1.22% because of desorption of EtOH was observed at temperature less than 200.5 °C; calcd. 1.38% for three EtOH molecules. IR (KBr) (cm−1): 1601 w, 1581 s, 1522 vw, 1476 m, 1422 m, 1305 vw, 1268 w, 1225 s, 1165 vw, 1096 w, 1062 m, 1000 vw, 957 s, 876 m, 812 vs, 782 vs, 682 m, 614 vw, 583 w, 522 w, 510 w, 481 w, 470 w, 409 w. 31P{1H} NMR (25.5 °C, DMSO-d6): δ −3.23, 26.31 (main), −0.40, 43.57 (minor) ppm. 1H NMR (24.7 °C, DMSO-d6): δ 1.09 (t, J = 7.1 Hz, CH3CH2OH solvate), 3.38 (q, J = 7.0 Hz, CH3CH2OH solvate), 7.35–7.57 (m, Aryl) ppm. Solid-state CPMAS 31P NMR (R.T.): δ −3.4, 24.4 ppm.
[(Au{P(m-FPh)3})4(μ4-O)]2[α-SiMo12O40]·4H2O (2): In the synthesis of 1, H4[α-SiMo12O40]·12H2O (0.102 g, 0.050 mmol) was used instead of H3[α-PMo12O40]·14H2O, and [Au(RS-pyrrld){P(m-FPh)3}] (0.257 g, 0.400 mmol) was also used. After 10 days, the yellow block crystals were formed. Yield: 0.014 g (4.64%). The crystalline samples were soluble in DMSO, but insoluble in H2O, EtOH and Et2O. Calcd. for C144H104O46F24Si1P8Mo12Au8 or [(Au{P(m-FPh)3})4(μ4-O)]2[α-SiMo12O40]·4H2O: C, 28.69; H, 1.74%. Found: C, 29.10; H, 1.49%. TG/DTA under atmospheric conditions: a weight loss of 1.07% because of desorption of H2O was observed at temperature less than 240.4 °C; calcd. 1.19% for four H2O molecules. IR (KBr) (cm−1): 1601 m, 1579 s, 1475 m, 1420 m, 1305 vw, 1268 w, 1225 s, 1163 vw, 1095 w, 999 vw, 984 vw, 943 m, 900 vs, 870 m, 806 vs, 796 vs, 784 vs, 691 s, 683 s, 628 m, 583 s, 523 s, 511 s, 469 s. 31P{1H} NMR (26.4 °C, DMSO-d6): δ 25.67 (main), 43.38 (minor) ppm. 1H NMR (25.0 °C, DMSO-d6): δ 7.37–7.72 (m, Aryl) ppm. Solid-state CPMAS 31P NMR (R.T.): δ 19.6, 24.4 ppm.
[(Au{P(m-MePh)3})4(μ4-O)]2[α-SiW12O40] (3): In the synthesis of 2, H4[α-SiW12O40]·10H2O (0.153 g, 0.050 mmol) was used instead of H4[α-SiMo12O40]·12H2O, and [Au(RS-pyrrld){P(m-MePh)3}] (0.252 g, 0.400 mmol) was also used in place of [Au(RS-pyrrld){P(m-FPh)3}]. After 10 days, the pale-yellow block crystals were formed. Yield: 0.247 g (71.4%). The crystalline samples were insoluble in H2O, EtOH, Et2O and DMSO. Calcd. for C168H168O42Si1P8W12Au8 or [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiW12O40]: C, 29.17; H, 2.45%. Found: C, 28.68; H, 2.17%. TG/DTA under atmospheric conditions: no weight loss was observed at below 214.6 °C. IR (KBr) (cm−1): 1592 w, 1576 w, 1476 m, 1448 m, 1403 m, 1379 w, 1311 w, 1277 vw, 1221 w, 1174 vw, 1108 m, 1039 vw, 1010 m, 996 w, 970 vs, 921 vs, 881 s, 805 vs, 691 vs, 569 m, 561 m, 531 s, 491 m, 465 m, 450 s. Solid-state CPMAS 31P NMR (R.T.): δ 18.3, 28.5 ppm.
[(Au{P(m-MePh)3})4(μ4-O)]2[α-SiMo12O40] (4): [Au(RS-pyrrld){P(m-MePh)3}] (0.252 g, 0.400 mmol) was dissolved in 25 mL of CH2Cl2. A yellow clear solution of H4[α-SiMo12O40]·12H2O (0.102 g, 0.050 mmol) dissolved in 15 mL of an EtOH–H2O (5:1, v/v) mixed solvent was slowly added along an interior wall of a round-bottomed flask containing a colorless clear solution of the phosphanegold(I) complex. The round-bottomed flask containing two layers was sealed and left in the dark at room temperature. After 7 days, the yellow block crystals formed around the interface of the two layers, which were collected on a membrane filter (JG 0.2 μm), washed with EtOH (20 mL × 2) and Et2O (20 mL × 2), and dried in vacuo for 2 h. Yield: 0.137 g (46.7%). The crystalline samples were insoluble in H2O, EtOH, Et2O and DMSO. Calcd. for C168H168O42Si1P8Mo12Au8 or [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiMo12O40]: C, 34.42; H, 2.89%. Found: C, 34.35; H, 2.70%. TG/DTA under atmospheric conditions: no weight loss was observed at below 222.4 °C. IR (KBr) (cm−1): 1591 w, 1575 w, 1475 w, 1446 w, 1403 w, 1310 vw, 1221 vw, 1174 vw, 1107 w, 1040 vw, 995 vw, 983 w, 947 s, 902 vs, 861 m, 804 vs, 794 vs, 691 m, 681 m, 568 w, 532 w, 491 w, 465 w, 449 m. Solid-state CPMAS 31P NMR (R.T.): δ 17.4, 27.7 ppm.
[{(Au{P(p-MePh)3})4(μ4-O)}{(Au{P(p-MePh)3})3(μ3-O)}][α-PW12O40] (5): A solution of [Au(RS-pyrrld){P(p-MePh)3}] (0.189 g, 0.300 mmol) dissolved in 25 mL of CH2Cl2 was slowly added to a colorless clear solution of Na3[α-PW12O40]·9H2O (0.155 g, 0.050 mmol) dissolved in 15 mL of an EtOH–H2O (5:1, v/v) mixed solvent. After stirring for 1 h at room temperature, the reaction solution was concentrated to 15 mL with a rotary evaporator at 30 °C. A pale-yellow white powder was collected on a membrane filter (JV 0.1 μm), washed with H2O (20 mL × 2), EtOH (20 mL × 2) and Et2O (20 mL × 2), and dried in vacuo for 2 h. At this stage, the pale-yellow white powder was obtained in a yield of 0.23 g.
Crystallization. The pale-yellow white powder (0.100 g) was dissolved in 20 mL of a CH2Cl2–EtOH (3:1, v/v) mixed solvent and was filtered through a folded filter paper (Whatman No. 5). The pale-yellow clear filtrate was slowly evaporated at room temperature in the dark. After 3 days, colorless plate crystals were formed and collected on a membrane filter (JV 0.1 μm), washed with EtOH (10 mL × 2) and Et2O (10 mL × 2), and dried in vacuo for 2 h. Yield: 0.026 g (26.0%). The crystalline samples were soluble in DMSO and sparingly soluble in CH2Cl2, but insoluble in H2O, EtOH and Et2O. Calcd. for C147H147O42P8W12Au7 or [{(Au{P(p-MePh)3})4(μ4-O)}{(Au{P(p-MePh)3})3(μ3-O)}][α-PW12O40]: C, 27.51; H, 2.31%. Found: C, 27.51; H, 2.63%. TG/DTA under atmospheric conditions: no weight loss was observed at below 203.6 °C. IR (KBr) (cm−1): 1597 w, 1496 w, 1445 w, 1397 w, 1309 vw, 1189 w, 1103 m, 1079 s, 977 s, 896 m, 821 vs, 802 vs, 706 w, 647 w, 633 w, 619 w, 526 m, 510 m. 31P{1H} NMR (26.7 °C, DMSO-d6): δ −14.88, 22.39 ppm. 1H NMR (25.6 °C, DMSO-d6): δ 2.25 (s, Me), 7.10–7.30 (m, Aryl) ppm. Solid-state CPMAS 31P NMR (R.T.): δ −14.6, 23.1 ppm.

3.4. X-ray Crystallography

Single crystals with dimensions of 0.30 × 0.08 × 0.07 mm3 for 1, 0.06 × 0.06 × 0.04 mm3 for 2, 0.23 × 0.13 × 0.07 mm3 for 3, 0.31 × 0.26 × 0.15 mm3 for 4 and 0.08 × 0.07 × 0.02 mm3 for 5 were mounted on cryoloops using liquid paraffin and cooled by a stream of cooled N2 gas. Data collection was performed on a Bruker (Madison, WI, USA) SMART APEX CCD diffractometer at 100 K for 1, 4 and 5, and Rigaku (Tokyo, Japan) VariMax with Saturn CCD diffractometer at 120 K for 2 and 3. The intensity data were automatically collected for Lorentz and polarization effects during integration. The structure was solved by direct methods (program SHELXS-97) followed by subsequent difference Fourier calculation and refined by a full-matrix, least-squares procedure on F2 (program SHELXL-97) [28]. Absorption correction was performed with SADABS (empirical absorption correction) [29]. The compositions and formulae of the POMs containing many solvated molecules were determined by CHN elemental analysis, TG/DTA and 1H NMR. Any solvent molecules in the structure were highly disordered and impossible to refine by using conventional discrete-atom models. To resolve these issues, the contribution of the solvent electron density was removed by using the SQUEEZE routine in PLATON for 1 [30]. The details of the crystallographic data for 1–5 are listed in Table 1, and bond lengths (Å) and angles (°) for 1–5 are shown in Tables S1–S5. CCDC 1028278 (1), 1028279 (2), 1028280 (3), 1028281 (4) and 1028282 (5), respectively. Polyhedral representation in Figure 1 was drawn by using the VESTA 3 series [31].

4. Conclusions

In this paper, we prepared and characterized various novel intercluster compounds 1–5 by POM-mediated clusterization. Formation of these gold(I) cluster cations in 1–5 was strongly dependent upon the charge density and acidity of the POMs, and substituted position on the aryl group of triarylphosphane ligands as well. The structures of phosphanegold(I) cluster cations were stabilized by the intra-cluster and inter-cluster aurophilic interactions, and also interactions between the gold(I) cluster cations and POM anions. The two free-acid forms of Keggin POMs with heteroatom Si provided the trigonal-pyramidal structures of the tetraphosphanegold(I) cluster cations in the intercluster compounds, i.e., [(Au{P(m-FPh)3})4(μ4-O)]2[α-SiMo12O40]·4H2O (2), [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiW12O40] (3) and [(Au{P(m-MePh)3})4(μ4-O)]2[α-SiMo12O40] (4). The reaction of the less-acidic Keggin POM, i.e., Na3[α-PW12O40]·9H2O, with the monomeric gold(I) precursor complex containing para-methyl group substituted triarylphosphane ligands has formed the intercluster compound of heptaphosphanegold(I) cluster cation, i.e., [{(Au{P(p-MePh)3})4(μ4-O)}{(Au{P(p-MePh)3})3(μ3-O)}][α-PW12O40] (5). This work suggests the synthetic routes of a variety of oxygen-centered phosphanegold(I) clusters formed by a combination of the monomeric phosphanegold(I) carboxylate and the various POMs such as Dawson and Anderson POMs, lacunary species of Keggin and Dawson POMs, and so on. Research in this direction is in progress.

Acknowledgments

This work was supported by JSPS KAKENHI grant number 22550065 and also by the Strategic Research Base Development Program for Private Universities of the Ministry of Education, Culture, Sports, Science and Technology of Japan.

Author Contributions

The synthesis and characterization of 1–4 were performed by Takuya Yoshida. The synthesis and characterization of 5 were performed by Yuta Yasuda. Characterization of these compounds were assisted by Eri Nagashima and Hidekazu Arai. Full research assistance and methodology were provided by Satoshi Matsunaga and Kenji Nomiya. The preparation of the manuscript was made by all the authors.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Pope, M.T.; Müller, A. Polyoxometalate Chemistry: An Old Field with New Dimensions in Several Disciplines. Angew. Chem. Int. Ed. Engl. 1991, 30, 34–48. [Google Scholar] [CrossRef]
  2. Hill, C.L.; Prosser-McCartha, C.M. Homogeneous catalysis by transition metal oxygen anion clusters. Coord. Chem. Rev. 1995, 143, 407–455. [Google Scholar] [CrossRef]
  3. Okuhara, T.; Mizuno, N.; Misono, M. Catalytic Chemistry of Heteropoly Compounds. Adv. Catal. 1996, 41, 113–252. [Google Scholar]
  4. Proust, A.; Thouvenot, R.; Gouzerh, P. Functionalization of polyoxometalates: Towards advanced applications in catalysis and materials science. Chem. Commun. 2008, 1837–1852. [Google Scholar]
  5. Long, D.-L.; Tsunashima, R.; Cronin, L. Polyoxometalates: Building Blocks for Functional Nanoscale Systems. Angew. Chem. Int. Ed. 2010, 49, 1736–1758. [Google Scholar] [CrossRef]
  6. Nomiya, K.; Sakai, Y.; Matsunaga, S. Chemistry of Group IV Metal Ion-Containing Polyoxometalates. Eur. J. Inorg. Chem. 2011, 2011, 179–196. [Google Scholar] [CrossRef]
  7. Schulz-Dobrick, M.; Jansen, M. Supramolecular Intercluster Compounds Consisting of Gold Clusters and Keggin Anions. Eur. J. Inorg. Chem. 2006, 2006, 4498–4502. [Google Scholar] [CrossRef]
  8. Schulz-Dobrick, M.; Jansen, M. Synthesis and Characterization of Intercluster Compounds Consisting of Various Gold Clusters and Differently Charged Keggin Anions. Z. Anorg. Allg. Chem. 2008, 634, 2880–2884. [Google Scholar] [CrossRef]
  9. Noguchi, R.; Hara, A.; Sugie, A.; Nomiya, K. Synthesis of novel gold(I) complexes derived by AgCl-elimination between [AuCl(PPh3)] and silver(I) heterocyclic carboxylates, and their antimicrobial activities. Molecular structure of [Au(R,S-Hpyrrld)(PPh3)] (H2pyrrld = 2-pyrrolidone-5-carboxylic acid. Inorg. Chem. Commun. 2006, 9, 355–359. [Google Scholar] [CrossRef]
  10. Nomiya, K.; Yoshida, T.; Sakai, Y.; Nanba, A.; Tsuruta, S. 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. Inorg. Chem. 2010, 49, 8247–8254. [Google Scholar] [CrossRef] [PubMed]
  11. Yoshida, T.; Nomiya, K.; Matsunaga, S. Novel intercluster compound between a heptakis{triphenylphosphinegold(I)}dioxonium cation and an α-Keggin polyoxometalate anion. Dalton Trans. 2012, 41, 10085–10090. [Google Scholar] [CrossRef] [PubMed]
  12. Yoshida, T.; Matsunaga, S.; Nomiya, K. 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. Dalton Trans. 2013, 42, 11418–11425. [Google Scholar] [CrossRef] [PubMed]
  13. Yoshida, T.; Matsunaga, S.; Nomiya, K. Novel Intercluster Compounds Composed of a Tetra{phosphanegold(I)}oxonium Cation and an α-Keggin Polyoxometalate Anion Linked by Three Monomeric Phosphanegold(I) Units. Chem. Lett. 2013, 42, 1487–1489. [Google Scholar] [CrossRef]
  14. Yoshida, T.; Yasuda, Y.; Nagashima, E.; Arai, H.; Matsunaga, S.; Nomiya, K. Template Effects of Polyoxometalate (POM) in the Formation of Dimer-of-Dinuclear Phosphanegold(I) Clusters by POM-Mediated Clusterization. Kanagawa university: Hiratsuka, Japan, Unpublished work. 2014. [Google Scholar]
  15. Schmidbaur, H. Ludwig Mond Lecture. High-carat gold compounds. Chem. Soc. Rev. 1995, 24, 391–400. [Google Scholar] [CrossRef]
  16. Schmidbaur, H.; Schier, A. A briefing on aurophilicity. Chem. Soc. Rev. 2008, 37, 1931–1951. [Google Scholar] [CrossRef] [PubMed]
  17. Gimeno, M.C.; Laguna, A. Chalcogenide centred gold complexes. Chem. Soc. Rev. 2008, 37, 1951–1966. [Google Scholar] [CrossRef]
  18. Nesmeyanov, A.N.; Perevalova, E.G.; Struchkov, Y.T.; Antipin, M.Y.; Grandberg, K.I.; Dyadchenko, V.P. Tris{triphenylphosphinegold}oxonium salts. J. Organomet. Chem. 1980, 201, 343–349. [Google Scholar] [CrossRef]
  19. Yang, Y.; Ramamoorthy, V.; Sharp, P.R. Late transition metal oxo and imido complexes. 11. Gold(I) oxo complexes. Inorg. Chem. 1993, 32, 1946–1950. [Google Scholar] [CrossRef]
  20. Angermaier, K.; Schmidbaur, H. A New Structural Motif of Gold Clustering at Oxide Centers in the Dication [Au6O2(PMe3)6]2+. Inorg. Chem. 1994, 33, 2069–2070. [Google Scholar] [CrossRef]
  21. Chung, S.-C.; Krüger, S.; Schmidbaur, H.; Rösch, N. A Density Functional Study of Trigold Oxonium Complexes and of Their Dimerization. Inorg. Chem. 1996, 35, 5387–5392. [Google Scholar] [CrossRef]
  22. Rocchiccioli-Deltcheff, C.; Fournier, M.; Franck, R.; Thouvenot, R. Vibrational Investigations of Polyoxometalates. 2. Evidence for Anion–Anion Interactions in Molybdenum(VI) and Tungsten(VI) Compounds Related to the Keggin Structure. Inorg. Chem. 1983, 22, 207–216. [Google Scholar] [CrossRef]
  23. Wells, A.F. Structural Inorganic Chemistry, 4th ed.; Clarendon Press: Oxford, UK, 1975; p. 1020. [Google Scholar]
  24. Bondi, A. van der Waals Volumes and Radii. J. Phys. Chem. 1964, 68, 441–451. [Google Scholar] [CrossRef]
  25. North, E.O.; Haney, W. Silicomolybdic Acid. Inorg. Synth. 1939, 1, 127–129. [Google Scholar]
  26. Tézé, A.; Hervé, G. α-, β-, and γ-Dodecatungstosilicic Acids: Isomers and Related Lacunary Compounds. Inorg. Synth. 1990, 27, 85–96. [Google Scholar]
  27. Aoki, S.; Kurashina, T.; Kasahara, Y.; Nishijima, T.; Nomiya, K. Polyoxometalate (POM)-based, multi-functional, inorganic-organi, hybrid compounds: Syntheses and molecular structures of silanol- and/or siloxane bond-containing species grafted on mono- and tri-lacunary Keggin POMs. Dalton Trans. 2011, 40, 1243–1253. [Google Scholar] [CrossRef] [PubMed]
  28. Sheldrick, G.M. A short history of SHELX. Acta Crystallogr. 2008, 64, 112–122. [Google Scholar] [CrossRef]
  29. Sheldrick, G.M. SADABS, Program for Area Detector Adsorption Correction; University of Göttingen: Göttingen, Germany, 1997. [Google Scholar]
  30. Spek, A.L. PLATON, an Integrated Tool for the Analysis of the Results of a Single Crystal Structure Determination. Acta Crystallogr. 1990, 46, c34. [Google Scholar]
  31. Momma, K.; Izumi, F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. Crystallogr. 2011, 44, 1272–1276. [Google Scholar] [CrossRef]

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MDPI and ACS Style

Yoshida, T.; Yasuda, Y.; Nagashima, E.; Arai, H.; Matsunaga, S.; Nomiya, K. Various Oxygen-Centered Phosphanegold(I) Cluster Cations Formed by Polyoxometalate (POM)-Mediated Clusterization: Effects of POMs and Phosphanes. Inorganics 2014, 2, 660-673. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics2040660

AMA Style

Yoshida T, Yasuda Y, Nagashima E, Arai H, Matsunaga S, Nomiya K. Various Oxygen-Centered Phosphanegold(I) Cluster Cations Formed by Polyoxometalate (POM)-Mediated Clusterization: Effects of POMs and Phosphanes. Inorganics. 2014; 2(4):660-673. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics2040660

Chicago/Turabian Style

Yoshida, Takuya, Yuta Yasuda, Eri Nagashima, Hidekazu Arai, Satoshi Matsunaga, and Kenji Nomiya. 2014. "Various Oxygen-Centered Phosphanegold(I) Cluster Cations Formed by Polyoxometalate (POM)-Mediated Clusterization: Effects of POMs and Phosphanes" Inorganics 2, no. 4: 660-673. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics2040660

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