Mixed Molybdenum-Vanadium Polyoxoanion-Bridged Trimetallic Nanocluster Complexes: Hydrothermal Syntheses and Crystal Structures of {MoVI6MoV2VIV8O40(PO4)[Co(phen)2(H2O)]2}[Co2(phen)2(OH)2(H2O)4]1/2 and {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}[Co(phen)3]·1.5H2O
CRYSTAL GROWTH & DESIGN 2003 VOL. 3, NO. 3 363-368
Cai-Ming Liu,* De-Qing Zhang,* and Dao-Ben Zhu Center for Molecular Science, Institute of Chemistry, Organic Solids Laboratory, Chinese Academy of Sciences, Beijing 100080, P. R. China Received December 20, 2002
ABSTRACT: Two novel trimetallic nanocluster complexes, {MoVI6MoV2VIV8O40(PO4)[Co(phen)2(H2O)]2}[Co2(phen)2(OH)2(H2O)4]1/2 (1) (phen ) 1,10′-phenanthroline) and {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}[Co(phen)3] ‚1.5H2O (2) (phen ) 1,10′-phenanthroline, en ) ethylenediamine), which are the first examples of mixed molybdenum-vanadium polyoxoanion bridged cluster complexes, have been hydrothermally prepared and characterized by X-ray crystallography. Introduction
Experimental Procedures
Organic-inorganic hybrid materials and polyoxometalates have received much attention because of not only their intriguing structural diversity but also their potential applications in molecular adsorption, ion exchange and heterogeneous catalysis, nanotechnology, as well as electrical, magnetic, photochemical areas.1,2 One of the important advances in design of new organicinorganic hybrid materials is utilizing polyoxometalates’ coordination abilities to produce polyoxoanion-supported or bridged transition metal complexes,3,4 whose properties thus become possibly modified at the molecular level.4b Many examples have been explored recently, including discrete clusters,2c,3b,3c one-dimensional chains,3d two-dimensional networks,4b,3e,3f and three-dimensional frameworks.3f We are interested in mixed molybdenumvanadium polyoxoanions’ coordination abilities and quite recently prepared successfully a two-dimensional mixed molybdenum-vanadium polyoxometalate, [Co(en)2][Co(bpy)2]2[PMoVI5MoV3VIV8O44]‚4.5H2O (en ) ethylenediamine, bpy ) 2,2′-bipyridine), where the [PMoVI5 MoV3VIV8O44] heteropolyoxometalate clusters are bridged by two types of cobalt complex fragments to form a layer framework.4b Herein we report the hydrothermal syntheses and crystal structures of two novel organicinorganic hybrid trimetallic nanocluster complexes: {MoVI6MoV2VIV8O40(PO4)[Co(phen)2(H2O)]2}[Co2(phen)2(OH)2(H2O)4]1/2 (1) (phen ) 1,10′-phenanthroline) and {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}[Co(phen)3]‚ 1.5H2O (2) (phen ) 1,10′-phenanthroline, en ) ethylenediamine), in which the mixed molybdenum-vanadium polyoxoanion [MoVI6Mo2VVIV8O40(PO4)]5- (for 1) or [MoVI5MoV3VIV8O40(PO4)]6- (for 2) acts as a bridge to link two cobalt(II) complex fragments, forming a trimetallic nanocluster anion. To our knowledge, 1 and 2 are the first examples of mixed molybdenum-vanadium polyoxoanion-supported or bridged trimetallic cluster complexes.
All reagents were obtained from commercial sources and used without further purification. The elemental analyses were performed on a Heraeus CHN-Rapid elemental analyzer. The infrared spectra were recorded on a Pekin-Elmer 2000 spectrophotometer with pressed KBr pellets. Synthesis of {MoVI6MoV2VIV8O40(PO4)[Co(phen)2(H2O)]2}[Co2(phen)2(OH)2(H2O)4]1/2 (1). A mixture of NH4VO3 (3.0 mmol), H3[P(Mo3O10)4]‚xH2O (0.5 mmol), Co(en)3Cl3(1.0 mmol), 1,10′-phenanthroline(1.0 mmol), and H2O (18 mL), stirred for 20 min, was transferred into a 25 mL Teflon-lined stainless steel autoclave and heated at 170 °C for 6 days. Dark block crystals of 1 were separated from the blue mother solution. Yield: 45% based on V. Anal. Calcd for C60H49Co3Mo8N10O49PV8: C 23.49; H 1.61; N 4.57. Found: C 23.35; H 1.70; N 4.49. IR (KBr pellet, cm-1): 1626(m), 1518(w), 1427(m), 1385(w), 1147(w), 1059(m), 942(s), 848(s), 795(s). Synthesis of {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}[Co(phen)3] ‚1.5H2O (2). A mixture of NH4VO3 (3.0 mmol), H3[P(Mo3O10)4]‚xH2O (0.5 mmol), Co(C2O4)2 (1.0 mmol), ethylenediamine (3.0 mmol), 1,10′-phenanthroline (1.0 mmol), and H2O (16 mL) in a 25 mL Teflon-lined stainless steel autoclave was heated at 170 °C for 10 days. Dark block crystals of 2 were obtained with a yield of 35% based on V. Anal. Calcd for C64H63Co3Mo8N14O47.50PV8: C 24.24; H, 2.00; N 23.97. Found: C 24.12, H 2.09, N 23.88. IR (KBr pellet, cm-1): 1589(m), 1460(w), 1280(w), 1027(m), 950(s), 772(m), 713(s). Single-Crystal X-ray Diffraction. For 1, the data were collected on a BRUKER SMART APEX CCD with Mo-KR radiation (λ ) 0.71073 Å) at 293(2) K. A total of 47 947 reflections were collected, of which 18 837 are unique (Rint ) 0.0420) and 8744 with I > 2σ(I). The structure was solved by Patterson method and refined by a full matrix least-squares technique based on F2 using SHELXL-97 program. All nonhydrogen atoms were refined anisotropically. All hydrogen atoms except for those in water molecules were placed at calculated positions, but their parameters were not refined. For 2, diffraction intensities were collected at 293(2) K on a Rigaku RAXIS RAPID IP imaging plate system with MoKR radiation (λ ) 0.71073 Å). A total of 20 501 reflections were collected, of which 10 815 are unique (Rint ) 0.0367) and 4641 with I > 2σ(I). The structure was solved by Patterson method and refined by a full matrix least-squares technique based on F2 using SHELXL 97 program. All non-hydrogen atoms were refined anisotropically, and all hydrogen atoms but those in hydrate molecules were allowed for as riding atoms.
* To whom correspondence should be addressed. E-mail: cmliu@ iccas.ac.cn.
10.1021/cg0200715 CCC: $25.00 © 2003 American Chemical Society Published on Web 03/11/2003
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Crystal Growth & Design, Vol. 3, No. 3, 2003 Table 1. Crystal Data and Structural Refinement Parameters for Complexes 1 and 2 1
formula
C60H49Co3Mo8N10O49PV8 fw 3067.82 crystal system monoclinic space group C/2c A (Å) 28.014(6) B (Å) 18.843(4) C (Å) 19.241(4) R (deg) 90.00 β (deg) 93.17(3) γ (deg) 90.00 U/Å3 10141(4) Z 4 T/K 293(2) λ(MoKR) Å 0.71073 Fcalc g cm-3 2.009 µ(MoKR) mm-1 2.230 total data collected 47947 unique data 18837 observed data (σ > 2σ(I)) 8744 R1a 0.0488 wR2b 0.1401 a
2 C64H63Co3Mo8N14O47.50PV8 3171.08 orthorhombic Pbcn 14.780(3) 23.748(5) 26.971(5) 90.00 90.00 90.00 9467(3) 4 293(2) 0.71073 2.214 2.393 20501 10815 4641 0.0512 0.1297
R1 ) ∑|Fo| - |Fc|/∑|Fo|. b wR2 ) ∑{[w(Fo2 - Fc2)2]/∑[wFo2]2}1/2.
Selected crystallographic data and structure determination parameters for complexes 1 and 2 are given in Table 1, and selected bond lengths and angles for complexes 1 and 2 are listed in Tables 2 and 3, respectively. The crystallographic data in CIF format for the structures of complexes 1 and 2 have been deposited with the Cambridge Crystallographic Data Center as supplementary publication nos. CCDC 195918 and 205434.
Liu et al. Table 2. Selected Bond Distances (Å) and Angles (deg) for Complex 1 V1-O16 V1-O11 V1-O13 V2-O10 V2-O11 V3-O5 V3-O17 V4-O12 Mo1-O20 Mo1-O2 Mo1-O11 Mo2-O15 Mo2-O6 Mo3-O6 Mo4-O23 Mo4-O8 Mo4-O17 Co1-O16 Co1-N3 Co1-N2 Co2-O25 Co2-O3W Co2-O2W
1.629(4) 1.922(4) 1.932(4) 1.970(4) 1.987(4) 1.923(4) 1.941(4) 1.973(4) 1.668(4) 1.871(4) 1.988(4) 1.675(4) 1.856(4) 1.860(4) 1.680(4) 1.855(4) 1.968(4) 2.050(3) 2.103(5) 2.136(5) 1.952(10) 2.158(14) 2.30(3)
V1-O10 V1-O19 V2-O21 V2-O17 V3-O3 V3-O12 V4-O18 V4-O5 Mo1-O7 Mo1-O19 Mo2-O4 Mo2-O2 Mo3-O1 Mo3-O8 Mo4-O7 Mo4-O5 Co1-N4 Co1-N1 Co1-O1W Co2-N5 Co2-N6 Co2-Co2a
1.912(4) 1.929(4) 1.614(4) 1.973(4) 1.613(4) 1.939(4) 1.591(4) 1.987(4) 1.855(4) 1.988(4) 1.961(4) 1.854(4) 1.661(4) 1.874(5) 1.866(4) 1.975(4) 2.089(5) 2.117(5) 2.167(4) 2.059(12) 2.176(10) 2.775(5)
O16-Co1-N4 N4-Co1-N3 N4-Co1-N1 O16-Co1-N2 N3-Co1-N2 O16-Co1-O1W O25-Co2-O3W O25-Co2-N6 O3W-Co2-N6 N5-Co2-O2W N6-Co2-O2W Co2-O25-Co2a
94.08(18) 78.7(2) 95.5(2) 170.82(16) 93.42(18) 86.04(14) 89.7(5) 176.7(5) 92.0(5) 85.5(7) 86.5(6) 89.6(4)
O16-Co1-N3 O16-Co1-N1 N3-Co1-N1 N4-Co1-N2 N1-Co1-N2 O25-Co2-N5 N5-Co2-O3W N5-Co2-N6 O25-Co2-O2W O3W-Co2-O2W O25-Co2-O25a
92.57(17) 96.38(17) 169.67(19) 93.91(19) 78.36(18) 98.0(4) 84.5(5) 79.3(4) 91.3(7) 170.1(7) 90.4(4)
a
Results and Discussion Synthesis. Hydrothermal methods have been utilized successfully to synthesize a great deal of novel inorganicorganic hybrid materials because difficulties due to differential solubilities of organic and inorganic precursors can be overcome.5 However, many factors such as temperature, pressure, acidity, reactant stoichiometry, and time of reaction can influence the outcome of reaction.5 For example, trimetallic nanocluster complex 1 was synthesized hydrothermally from a mixture of NH4VO3, H3[P(Mo3O10)4]‚xH2O, Co(en)3Cl3, 1,10′-phenanthroline, and water in the molar ratio of 3:0.5:1:1:1000 at 170 °C for 6 days. While the two-dimensional mixed molybdenum-vanadium polyoxometalate, [Co(en)2][Co(bpy)2]2[PMoVI5MoV3VIV8O44]‚4.5H2O,4b was obtained supposedly 2,2′-bipyridine instead of 1,10′-phenanthroline was used under similar hydrothermal conditions. In addition, the reaction of NH4VO3, H3[P(Mo3O10)4]‚xH2O, Co(C2O4)2, ethylenediamine, 1,10′-phenanthroline, and water in the molar ratio of 3:0.5:1:3:1:1000 at 170 °C for 10 days yielded another type of trimetallic nanocluster complex 2. On the basis of our own experience4b and that of others3j,6 in mixed molybdenum-vanadium polyoxometalate synthesis, we found that when NH4VO3 and H3[P(Mo3O10)4]‚xH2O were used as starting materials, the formed mixed molybdenum-vanadium polyoxoanion is inclined to act as a ligand to link complex fragments, whereas if the corresponding precursors were replaced by NH4VO3, Na2MoO4, and phosphorous acid, the formed mixed molybdenumvanadium polyoxoanion generally acts as a balance ion.3j,6 Perhaps the main reason is that the phosphorous
1-X, 2-Y, 2-Z.
Table 3. Selected Bond Distances (Å) and Angles (deg) for Complex 2 V1-O20 V1-O24 V1-O23 V2-O19 V2-O16 V3-O13 V3-O9 V3-O19 V4-O14 Mo1-O6 Mo1-O5 Mo1-O16 Mo2-O7 Mo2-O14 Mo3-O17 Mo3-O9 Mo4-O22 Co1-O13 Co1-N4 Co1-N3 Co2-N6 Co2-N5
1.610(7) 1.939(7) 1.944(7) 1.956(7) 1.986(7) 1.625(7) 1.928(8) 1.933(8) 1.986(7) 1.661(7) 1.890(9) 1.993(7) 1.863(8) 1.993(7) 1.678(7) 1.984(8) 1.685(7) 2.070(7) 2.077(10) 2.094(11) 2.076(8) 2.086(9)
V1-O16 V1-O10 V2-O21 V2-O15 V2-O23 V3-O15 V3-O14 V4-O11 V4-O9 Mo1-O7 Mo1-O10 Mo2-O18 Mo2-O12 Mo2-O15 Mo3-O8 Mo3-O19 Mo4-O12 Co1-N2 Co1-N1 Co1-O1W Co2-N7
1.923(7) 1.942(7) 1.588(7) 1.973(8) 2.006(7) 1.921(7) 1.932(7) 1.602(7) 2.009(8) 1.840(9) 1.978(8) 1.656(8) 1.863(7) 2.004(7) 1.884(9) 2.002(7) 1.853(7) 2.076(11) 2.084(10) 2.117(9) 2.079(10)
O13-Co1-N2 N2-Co1-N4 N2-Co1-N1 O13-Co1-N3 N4-Co1-N3 O13-Co1-O1W N4-Co1-O1W N3-Co1-O1W N6-Co2-N5
95.6(3) 91.9(4) 78.9(4) 90.0(4) 85.1(4) 81.1(3) 171.7(4) 91.2(5) 78.9(3)
O13-Co1-N4 O13-Co1-N1 N4-Co1-N1 N2-Co1-N3 N1-Co1-N3 N2-Co1-O1W N1-Co1-O1W N6-Co2-N7 N7-Co2-N5
91.4(4) 174.2(4) 90.3(4) 173.8(4) 95.7(4) 92.4(5) 97.5(4) 87.7(4) 92.4(4)
acid in the latter not only is incorporated into the structure (as PO43- anion) but also adjusts the pH value of reactant solution.
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Figure 1. Structure of [Co(phen)(OH)(H2O)2]2{MoVI6MoV2VIV8O40(PO4)[Co(phen)2(H2O)]2} (1). The disordered PO43- anion guest inside polyoxoanion [PMoVI6MoV2VIV8O44]5- is omitted for clarity.
Crystal Structures. The structure of complex 1 consists of discrete trimetallic polyoxoanion {MoVI6Mo2VVIV8O40(PO4)[Co(phen)2(H2O)]2}- and binuclear cation [Co2(phen)2(OH)2(H2O)4]2+ (Figure 1). The trimetallic polyoxoanion {MoVI6Mo2VVIV8O40(PO4)[Co(phen)2(H2O)]2}- is composed of mixed molybdenum-vanadium polyoxoanion [VIV8MoVI6MoV2O40(PO4)]5- and two opposite covalently linked cobalt(II) complex fragments Co(phen)2(H2O)2+, with a Co‚‚‚Co separation distance of 14.843 Å. The only reported example with mixed molybdenum-vanadium polyoxoanion [PMoVI6MoV2VIV8O44]5- is {Co(tea)2}2Na[PMoVI6MoV2VIV8O44]‚8H2O (tea ) triethylenediamine),6 where the [PMoVI6MoV2VIV8O44]5- polyoxoanion is the only discrete anion and the transition metal complex Co(tea)2 just acts as a balance ion. Other complexes [Ni(tea)2]3[PMoVI5MoV3VIV8O44]‚tea‚H2O (tea ) triethylenediamine)6 and [Co(en)2][Co(bpy)2]2[PMoVI5 MoV3VIV8O44]‚4.5H2O4b also possess similar mixed molybdenum-vanadium polyoxoanion [PMoVI5MoV3VIV8O44]6-, but their net valences are -6. The polyoxoanion [PMoVI6MoV2VIV8O44]5- in 1 is identical to that in {Co(tea)2}2Na[PMoVI6MoV2VIV8O44]‚ 8H2O.6 It reveals a tetracapped Keggin cluster based on R-Keggin structure with four additional five-coordinated terminal VO2+ units to form a hexadecametal host shell, [MoVI6MoV2VIV8O40]3-, and there is a disordered PO43- anion inside this host shell as a guest. The Mo-O and V-O bond lengths [Mo-Ot, 1.661(4)-1.680(4) Å; Mo-Ob, 1.854(4)-2.017(4) Å; V-Ot, 1.591(4)-1.629(4) Å and V-Ob, 1.912(4)-2.000(4) Å] are comparable with those in {Co(tea)2}2Na[PMoVI6MoV2VIV8O44]‚8H2O [MoOt, 1.652(10)-1.678(7) Å; Mo-Ob, 1.834(11)-1.991(9) Å; V-Ot, 1.600(8)-1.643(13) Å and V-Ob, 1.918(7)-1.983-
(9) Å].6 Each of two cobalt atoms in the trimetallic polyoxoanion {MoVI6Mo2VVIV8O40(PO4)[Co(phen)2(H2O)]2}is coordinated by two 1,10′-phenanthroline ligands, one tetracapped Keggin anion [PMoVI6MoV2VIV8O44]5-, and one water molecule, with Co-Ow 2.167(4) Å and Co-N 2.089(5)-2.103(5) Å and 2.117(5)-2.136(5) Å. A µ-oxygen, O16 connects the tetracapping Keggin unit and the Co1 atom, with Co1-O16 2.050(3) Å. Two [Co(phen)2(H2O)]2+ fragments link two terminal V-O groups from opposite sides. The O16-V1 bond length of 1.629(4) Å is longer than other V-Ot bond distances [1.591(4)1.614(4) Å]. In the binuclear cation [Co2(phen)2(OH)2(H2O)4]2+, two hydroxide ions bridge two cobalt centers to generate a Co2(µ-OH)2 core. Each Co(II) center is approximately octahedrally coordinated by one bidentate 1,10′-phenanthroline ligand, two coordination water molecule, and two(bridging) hydroxyl oxygen atoms. The Co-Ohydroxo bond lengths [1.952(10) and 1.988(11) Å] are within normal value range,7 but the Co‚‚‚Co separation distance [2.775(5) Å] is obviously shorter than that of other dinulear Co(II)-bis(µ-hydroxo) complexes [Co2L2(µ-OH)2][ClO4]2‚MeCN {L ) bis[3-(2-pyridyl)pyrazol-l-yl]methane}[2.919(1) Å],7a [Co(HB(3,5-iPr2pz)3)2(OH)2‚2C5H12 [HB(3,5-iPr2pz)3 ) hydrotris(3,5-diisopropyl-1-pyrazolyl)borate] [ 3.202(3) Å]7b and LCo(µ-OH)2CoL (L ) hydrotris(pyrazolyl)borate) [3.141(2) Å].7c Interestingly, two 1,10′-phenanthroline planes and the Co2O2 core plane are almost coplanar, with the Co-N bond distances of 2.059(12) and 2.176(10) Å making [Co2(phen)2(OH)2(H2O)4]2+ cation adopt quite unusual configuration. Hydrogen bonds play important roles in stabilizing the molecule in the crystal structure. The anions connect
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Figure 2. A packing diagram of the unit cell of complex 1 looking down the c-axis showing hydrogen-bonding contacts between cations and polyoxoanions as well as among polyoxoanions.
Figure 3. Structure and atom numbering of {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}2- (anion of 2).
each other through hydrogen bonding with O1w‚‚‚O15 (or their symmetry equivalents) distance of 2.797 Å, generating an anion layer along the bc plane (Figure 2), while the cations were exactly deposited between two anion layers to form the cation layers, and the cations link the anions via strong hydrogen bondings with a corresponding O3w‚‚‚O3 (or their symmetry equivalents) distance of 2.620 Å. These hydrogen bonds force the structure of 1 to extend into an interesting threedimensional supramolecular array. The crystal structure of 2 is composed of discrete trimetallic polyoxoanion {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}2-, cation [Co(phen)3]2+, and solvent water molecules. As shown in Figure 3, the trimetallic polyoxoanion {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}2- consists of mixed molybdenum-vanadium polyoxoanion [MoVI5MoV3VIV8O40(PO4)]6- and two opposite covalently linked cobalt(II) complex fragments
[Co(phen)(en)(H2O)] 2+. The Co‚‚‚Co separation distance of 15.160 Å is a little longer than that in [VIV8MoVI6MoV2O40(PO4)]5- of 1 (14.843 Å). The polyoxoanion [MoVI5MoV3VIV8O40(PO4)]6- is identical to those in complexes [Ni(tea)2]3[PMoVI5MoV3VIV8O44]‚tea‚H2O 6 and [Co(en)2][Co(bpy)2]2[PMoVI5 MoV3VIV8O44]‚4.5H2O.4b The Mo-O and V-O bond lengths [Mo-Ot, 1.661(4)-1.680(4) Å; Mo-Ob, 1.840(9)-2.004(7) Å; V-Ot, 1.588(7)-1.625(7) Å and V-Ob, 1.921(7)-2.009(8) Å] are comparable with those in [Ni(tea)2]3[PMoVI5MoV3VIV8O44]‚tea‚H2O6 [MoOt, 1.664(6)-1.706(5) Å; Mo-Ob, 1.853(10)-2.037(10) Å; V-Ot, 1.562(14)-1.713(10) Å and V-Ob, 1.890(11)2.105(9) Å], in [Co(en)2][Co(bpy)2]2[PMoVI5 MoV3VIV8O44]‚ 4.5H2O [Mo-Ot, 1.663(3)-1.689(3) Å; Mo-Ob, 1.853(3)1.981(3) Å; V-Ot, 1.597(3)-1.650(3) Å and V-Ob, 1.918(3)-1.993(3) Å] 4b, in 1 [Mo-Ot, 1.661(4)-1.680(4) Å; Mo-Ob, 1.854(4)-2.017(4) Å; V-Ot, 1.591(4)1.629(4) Å and V-Ob, 1.912(4)-2.000(4) Å] and in
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Figure 4. Top view showing the 1D chain in 2. Hydrogen bonds are represented by broken lines.
{Co(tea)2}2Na[PMoVI6MoV2VIV8O44]‚8H2O [Mo-Ot, 1.652(10)-1.678(7) Å; Mo-Ob, 1.834(11)-1.991(9) Å; V-Ot, 1.600(8)-1.643(13) Å and V-Ob, 1.918(7)-1.983(9) Å].6 Each of two cobalt atoms linked to the tetra-capped Keggin anion [MoVI5MoV3VIV8O40(PO4)]6- is coordinated by one 1,10′-phenanthroline ligand, one ethylenediamine ligand, one water molecule and one terminal oxygen atom from [MoVI5MoV3VIV8O40(PO4)]6-. The CoOw bond distance of 2.117(9) Å is slightly shorter than that in 1 (2.167(4) Å), and the Co-N bond lengths of 2.076(11)-2.084(10) Å and 2.077(10)-2.094(11) Å are comparable with those in the cation Co(phen)32+ [2.076(8)-2.086(9) Å]. Two [Co(phen)(en)(H2O)]2+ fragments connect two terminal V-O groups as the [Co(phen)2(H2O)]2+ fragments in 1 do. The six-coordinated transition metal complex moiety serving as the cation also found in another polyoxoanion-supported cluster complex [Ni(2,2′-bipy)3]1.5[PW12O40Ni(2,2′-bipy)2 (H2O)]‚ 0.5H2O.3b It is also striking that the structure of complex 2 exhibits a hydrogen bonding interaction among anions [O20‚‚‚N4 (or their symmetry equivalents) 2.943 Å], generating a chain along the b axis (Figure 4). The cations as well as solvent water molecules are situated among these chains, but the water molecules are not involved with hydrogen bondings. Conclusions The successful syntheses of 1 and 2 provide novel examples of assembling the interesting mixed molyb-
denum-vanadium polyoxoanion bridged nanocluster complexes under hydrothermal conditions. The variations in the structures arise due to not only the differences in the covalently linked transitional complex fragments but also those in the balance cations. This study demonstrates the possibility of bridging transition metal complexes with heterometallic polyoxoanion to generate trimetallic nanocluster complexes, and suggests a synthetic approach to new trimetallic nanoclusters by using heterometallic polyoxoanion as bridges. Acknowledgment. This work was supported by the National Natural Science Foundation of China (No. 20201012), the Major State Basic Research Development Program of P. R. China and Chinese Academy of Sciences. References (1) Hagrman, P. J.; Hagrman, D.; Zubieta, J. Angew. Chem., Int. Ed. Engl. 1999, 38, 2638; Centi, G.; Trifro, F.; Ebbner, J. R.; Franchetti, V. M. Chem. Rev. 1988, 88, 55. (2) (a) Hill, C. L. Ed. Chem. Rev. 1998, 98, 1-390 (special issue on polyoxometalates); (b) Corma, A. Chem. Rev. 1995, 95, 559. (c) Piepenbrink, M.; Triller, M. U.; Gorman, N. H. J.; Krebs, B. Angew. Chem., Int. Ed. Engl. 2002, 41, 2523. (d) Pope, M. T.; Mu¨ller, A. Angew. Chem., Int. Ed. Engl. 1991, 30, 34. (3) (a) Mu¨ller, A.; Koop, M.; Schiffels, P.; Bo¨gge, H. Chem. Commun. 1997, 1715. (b) Xu, Y.; Xu, J.-Q.; Zhang, K.-L.; Zhang, Y.; You, X.-Z. Chem. Comm. 2000, 153. (c) Xu, J.Q.; Wang, R.-Z.; Yang, G.-Y.; Xing, Y.-H.; Li, D.-M.; Bu, W.M.; Ye, L.; Fan, Y.-G.; Yang, G.-D.; Xing, Y.; Lin, Y.-H.; Jia, H.-Q. Chem. Commun. 1999, 983. (d) Zapf, P. J.; Warren,
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