Two heterometallic deca-vanadate(V) compounds, bis-(tetra-methyl-ammonium) deca-aquadi-μ4-oxido-tetra-μ3-oxido-hexa-deca-μ2-oxido-hexa-oxidodimang-anese(II)-deca-vanadate(V) penta-hydrate, (Me4N)2[V10O28{Mn(H2O)5}2]·5H2O, A, and bis-{[tris-(hy-droxy-meth-yl)meth-yl]ammonium} deca-aquadi-μ4-oxido-tetra-μ3-oxido-hexa-deca-μ2-oxido-hexa-oxidodimanganese(II)deca-vanadate(V) dihydrate, [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O, B, have been synthesized under mild reaction conditions in an aqueous medium. Both polyanions present two [Mn(OH2)5](2+) complex units bound to the deca-vanadate cluster through oxide bridges. In A, the deca-vanadate unit has 2/m symmetry, whereas in B it has twofold symmetry. Apart from this, the main differences between A and B rest on the organic cations, tetra-methyl-ammonium and [tris-(hy-droxy-meth-yl)meth-yl]ammonium, respectively, and on the number and arrangement of the water mol-ecules of crystallization. In both compounds, the H atoms from the coordinating water mol-ecules participate in extensive three-dimensional hydrogen-bonding networks, which link the cluster units both directly and through solvent mol-ecules and, in B, through the 'tris-' cation hydroxyl groups. The cation in B also participates in N-H⋯O hydrogen bonds. A number of C-H⋯O inter-actions are also observed in both structures.
Two heterometallic deca-vanadate(V) compounds, bis-(tetra-methyl-ammonium) deca-aquadi-μ4-oxido-tetra-μ3-oxido-hexa-deca-μ2-oxido-hexa-oxidodimang-anese(II)-deca-vanadate(V) penta-hydrate, (Me4N)2[V10O28{Mn(H2O)5}2]·5H2O, A, and bis-{[tris-(hy-droxy-meth-yl)meth-yl]ammonium} deca-aquadi-μ4-oxido-tetra-μ3-oxido-hexa-deca-μ2-oxido-hexa-oxidodimanganese(II)deca-vanadate(V) dihydrate, [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O, B, have been synthesized under mild reaction conditions in an aqueous medium. Both polyanions present two [Mn(OH2)5](2+) complex units bound to the deca-vanadate cluster through oxide bridges. In A, the deca-vanadate unit has 2/m symmetry, whereas in B it has twofold symmetry. Apart from this, the main differences between A and B rest on the organic cations, tetra-methyl-ammonium and [tris-(hy-droxy-meth-yl)meth-yl]ammonium, respectively, and on the number and arrangement of the water mol-ecules of crystallization. In both compounds, the H atoms from the coordinating water mol-ecules participate in extensive three-dimensional hydrogen-bonding networks, which link the cluster units both directly and through solvent mol-ecules and, in B, through the 'tris-' cation hydroxyl groups. The cation in B also participates in N-H⋯O hydrogen bonds. A number of C-H⋯O inter-actions are also observed in both structures.
Research on the electronic properties, catalytic activities and biological roles of polyoxidovanadates has advanced enormously during the last few decades (Bošnjaković-Pavlović et al., 2009 ▸; Liu & Zhou, 2010 ▸). Among these aggregates, the decavanadate(V) anion is the most intensively studied because of its biological effect on the activities of several enzymes (Aureliano & Ohlin, 2014 ▸) and its insulin-mimetic action (Chatkon et al., 2013 ▸; Aureliano, 2014 ▸). The first functionalization of decavanadate anions, [HnV10O28](6−, with transition metal complexes was reported in 2007 (Li et al., 2007 ▸). Since then, structures involving different binding modes with non-equivalent terminal and bridging oxido ligands have been described (Wang, Sun et al., 2008 ▸; Wang, Yan et al., 2008 ▸; Wang et al., 2011 ▸; Long et al., 2010 ▸; Xu et al., 2012 ▸) and examples with first-row, d-block metal ions include complexation with copper(II), manganese(II) and zinc(II) (Wang, Sun et al., 2008 ▸; Wang et al., 2011 ▸; Klištincová et al., 2009 ▸, 2010 ▸; Pavliuk et al., 2014 ▸).Polyoxidovanadates containing manganese cations have been synthesized as ionic pairs (Shan & Huang, 1999 ▸; Lin et al., 2011 ▸) or as heterometallic aggregates in which the oxidovanadate cluster acts as a metalloligand to the manganese complex (Inami et al., 2009 ▸; Klištincová et al., 2009 ▸). Recent interest in this kind of compound lies in a possible synergistic effect (involving the two metal elements) for the enhancement of the catalytic activity towards oxidation of organic substrates, such as in the photocatalytic degradation of dyes (Wu et al., 2012 ▸).While the synthesis of decavanadates with different organic cations as building blocks for supramolecular assemblies is largely explored (da Silva et al., 2003 ▸), a systematic procedure for their functionalization with transition metal complexes has not been well established. Our research group is currently involved in the synthesis of heterometallic polyoxidovanadates containing manganese(II) because of their potential activity as catalysts of olefin epoxidation. In this context, the reaction between NH4VO3 and mannitol to give A was carried out in aqueous solution in the presence of tetramethylammonium chloride (molar proportion 2:1:2), following a procedure described earlier by our group to produce the mixed-valence polyoxidovanadate(Me4N)6[V15O36(Cl)] (Nunes et al., 2012 ▸). The dark-green solution obtained after reflux for 24 h received one molar equivalent of Mn(OAc)2·4H2O and was kept under reflux for 24 more hours. A mixture of dark-green crystals of (Me4N)6[V15O36(Cl)] and yellow prisms of (NMe4)2[V10O28{Mn(H2O)5}2]·5H2O (A) was isolated after four weeks at room temperature, the latter in 9% yield. Product A contains two tetramethylammonium cations and the [V10O28]6– unit is covalently bound to two [Mn(OH2)5]2+ complexes by terminal oxido bridges.The rational synthesis of the heteropolyanion [V10O28{Mn(H2O)5}2]2–, in its turn, was achieved by reaction of NH4VO3 with tris(hydroxymethyl)methylamine (‘tris’) and manganese(II) chloride at pH 3 in a 5:3:1 molar proportion. Yellow crystals of [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O (B) were isolated in 12% yield, as the only reaction product, after one week at room temperature. X-ray diffraction analyses revealed very similar structures for the heteropolyanions in A and B.
Structural commentary
The anionic heteropolyanions are essentially identical in the two complexes. However, in A, the molecule lies about the centre of the cell which is a point of 2/m symmetry, so that the unique part of the anionic cluster is one quarter of that heteropolyanion. The anion lies about a mirror plane which passes through the V2, V4 and manganese atoms, and there is a twofold symmetry axis which is perpendicular to the mirror plane and passes through V3 and the centre of the cell, Fig. 1 ▸.
Figure 1
View of the components of (NMe4)2[V10O28{Mn(H2O)5}2]·5H2O, A, indicating the atom-numbering scheme. No H atoms were identified on the disordered solvent water molecules. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (1) 1 − x, y, 1 − z; (2) 1 − x, 1 − y, 1 − z; (3) x, 1 − y, z; (4) 1 − x, −y, −z; (5) 1 − x, y, −z.]
The V10O28 moiety in the structure of compound B lies about a twofold symmetry axis which passes through the vanadium atoms V6 and V7, Fig. 2 ▸. This is the only crystallographic symmetry in this ion which, nevertheless, shows a very similar structure to that found in the ion in compound A; views showing this pseudo-symmetry are presented in Figs. 3 ▸, 4 ▸ and 5 ▸. The unique part here is one half of the anion. The previously reported analysis of this anion [with a 2-(2-hydroxyethyl)pyridinium cation] showed the cluster to be lying about an inversion centre (Klištincová et al., 2009 ▸).
Figure 2
The corresponding view for [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O, B. [Symmetry code: (1) 1 − x, y, − z.]
Figure 3
The anion of compound B viewed approximately down the a axis of the V10O28 moiety. [Symmetry code: (1) 1 − x, y, − z.]
Figure 4
The anion of compound B viewed approximately down the b axis of the V10O28 moiety. [Symmetry code: (1) 1 − x, y, − z.]
Figure 5
The anion of compound B viewed approximately down the c axis of the V10O28 moiety. [Symmetry code: (1) 1 − x, y, − z.]
Bond angles and lengths determined for [V10O28{Mn(H2O)5}2]2– are in the ranges reported in the literature (Klištincová et al., 2009 ▸). In both our compounds, there is a wide range of V—O bond lengths. The vanadium atoms on the outer shell of the heteropolyanions, e.g. V4 and V5 in A, and V2–V5 in B, are five-coordinate with a square-pyramidal pattern; there is a sixth oxygen atom in the direction of an octahedral site but, at ca 2.3 Å from the vanadium atom, rather longer than the normal coordination distance. Of the five bonded oxygen atoms, the apical site (opposite the distant, sixth, site) has the shortest V—O distance, ca 1.6 Å, corresponding to a vanadyl group. The more ‘internal’ vanadium atoms in each structure, viz V3 in A, and V6 and V7 in B, have more uniform V—O distances in more regular octahedral patterns.
Supramolecular features
In both compounds, O—H⋯O hydrogen bonds from all the coordinating water molecules link the anions with neighbouring anions, either directly, through both the cluster O atoms and the coordinating water molecules, or indirectly through the solvent water molecules (Tables 1 ▸ and 2 ▸). In compound B, additional hydroxyl groups are available in the ‘tris’ cation, and these add further links in the extensive hydrogen bonding scheme. Additional C—H⋯O interactions are observed in the structures of both compounds.
For structures with the [V10O28{Mn(H2O)5}2]2– heteropolyanion, see: Klištincová et al. (2009 ▸). For structures with manganese(II) coordination complexes as counter-ions for [V10O28]6–, see: Klištincová et al. (2010 ▸); Shan & Huang (1999 ▸); Lin et al. (2011 ▸) and Mestiri et al. (2013 ▸).
Synthesis and crystallization
GeneralAll reactions were performed in air with purified (Milli-Q®) water. Commercial reagents were used without purification. The starting materials NH4VO3, MnCl2·4H2O and Mn(OAc)2·4H2O were supplied by Aldrich, while mannitol [C6H8(OH)6] and (Me4N)Cl were purchased from USB and Merck, respectively. Infrared (FTIR) spectra were recorded on a BIORAD FTS-3500GX spectrophotometer from KBr pellets in the 400–4000 cm−1 region.Synthesis of (NMeSolid NH4VO3 (0.500 g, 4.27 mmol) and [(CH3)4N]Cl (0.468 g, 4.27 mmol) were added to a solution of mannitol (0.366 g, 2.13 mmol) in 60 mL of water to produce a suspension that turned into a deep blue–greenish solution after one hour under reflux. After 24 more hours, a solution of Mn(OAc)2·4H2O (1.04 g, 4.27 mmol) in 10 mL of water was added to this reaction mixture, which remained under reflux for one more day. The solution was concentrated to one third of its initial volume and, after four weeks at room temperature, a mixture of deep-green crystals of (Me4N)6[V15O36(Cl)] (Nunes et al., 2012 ▸) and yellow prisms of A was obtained, the latter in 9% yield based on vanadium (56 mg). The FTIR spectrum recorded for A shows the characteristic bands of the Me4N+ cation at 3031, 1639, 1485 and 1263 cm−1 and of the inorganic anion at 966, 833, 744, 584 and 455 cm−1.Synthesis of [NHA solution containing tris(hydroxymethyl)methylamine (0.720 g, 6.0 mmol) in 20 mL of water was added to a solution of NH4VO3 (1.17 g, 10.0 mmol) in the same volume of solvent. This reaction mixture was then refluxed until it became a clear solution, after which its pH was adjusted to 3 with aqueous HCl. A solution of MnCl2·4H2O (0.394 g, 2.0 mmol) in 10 mL of water was then added as a layer on top of the reaction mixture and, after two weeks at room temperature, yellow crystals of B were obtained (180 mg) in 12% yield based on vanadium. The FTIR spectrum of B shows characteristic bands of the trisH+ cation at 3188, 2927, 2856, 1743, 1637, 1417, 1161 and 1112 cm−1 and of the inorganic anion at 941, 842 and 684 cm−1.
Refinement details
Crystal data, data collection and structure refinement details for the two structures are summarized in Table 3 ▸.
Table 3
Experimental details
Compound A
Compound B
Crystal data
Chemical formula
(C4H12N)2·[Mn2V10O28(H2O)10]·5H2O
(C4H12NO3)2[Mn2V10O28(H2O)10]·2H2O
Mr
1485.81
1527.76
Crystal system, space group
Monoclinic, I2/m
Monoclinic, C2/c
Temperature (K)
292
295
a, b, c (Å)
13.2434 (7), 9.6402 (5), 17.7628 (13)
19.3147 (8), 9.7733 (4), 22.7952 (10)
β (°)
98.626 (2)
96.392 (1)
V (Å3)
2242.1 (2)
4276.3 (3)
Z
2
4
Radiation type
Mo Kα
Mo Kα
μ (mm−1)
2.64
2.78
Crystal size (mm)
0.48 × 0.38 × 0.15
0.49 × 0.26 × 0.13
Data collection
Diffractometer
Bruker D8 Venture/Photon 100 CMOS
Bruker D8 Venture/Photon 100 CMOS
Absorption correction
Multi-scan (SADABS; Bruker, 2012 ▸)
Multi-scan (SADABS; Bruker, 2012 ▸)
Tmin, Tmax
0.562, 0.746
0.542, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections
81983, 2953, 2752
71752, 3936, 3280
Rint
0.025
0.039
(sin θ/λ)max (Å−1)
0.668
0.605
Refinement
R[F2 > 2σ(F2)], wR(F2), S
0.020, 0.060, 1.09
0.052, 0.114, 1.12
No. of reflections
2953
3936
No. of parameters
194
385
No. of restraints
0
6
H-atom treatment
H atoms treated by a mixture of independent and constrained refinement
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ2(Fo2) + (0.0329P)2 + 2.2668P] where P = (Fo2 + 2Fc2)/3
w = 1/[σ2(Fo2) + (0.0062P)2 + 110.7865P] where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å−3)
0.58, −0.34
0.78, −1.11
Computer programs: APEX2 and SAINT (Bruker, 2010 ▸), SHELXS97, SHELXL97 (Sheldrick, 2008 ▸), SHELXL2013 and SHELXL2014 (Sheldrick, 2015 ▸), ORTEP-3 for Windows and WinGX (Farrugia, 2012 ▸).
Hydrogen atoms on the cation were included in idealized positions (with methyl and methylene group C—H distances set at 0.96 and 0.97 Å, N—H at 0.89 Å and O—H at 0.82 Å) and their U
iso values were set to ride on the U
eq values of the parent atoms. Hydrogen atoms in the anions (on coordinating water molecules) were located in difference maps and were refined freely.There are two independent solvent water molecules, one of which is disordered over two sites close to a centre of symmetry, in compound A. No hydrogen atoms were identified in these water molecules.In B, there is one solvent water molecule which is disordered over two sites; the hydrogen atoms here were located in difference maps and were refined with distance restraints [O—H = 0.82 (2) Å].Crystal structure: contains datablock(s) Compound-A, Compound-B, global. DOI: 10.1107/S2056989014028230/hb7337sup1.cifStructure factors: contains datablock(s) mpf-A. DOI: 10.1107/S2056989014028230/hb7337mpf-Asup2.hklClick here for additional data file.Supporting information file. DOI: 10.1107/S2056989014028230/hb7337mpf-Asup4.cdxStructure factors: contains datablock(s) mpf-B. DOI: 10.1107/S2056989014028230/hb7337mpf-Bsup3.hklClick here for additional data file.Supporting information file. DOI: 10.1107/S2056989014028230/hb7337mpf-Bsup5.cdxCCDC references: 1041495, 1041494Additional supporting information: crystallographic information; 3D view; checkCIF report
Primary atom site location: structure-invariant direct methods
Least-squares matrix: full
Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020
Hydrogen site location: mixed
wR(F2) = 0.060
H atoms treated by a mixture of independent and constrained refinement
S = 1.09
w = 1/[σ2(Fo2) + (0.0329P)2 + 2.2668P] where P = (Fo2 + 2Fc2)/3
2953 reflections
(Δ/σ)max = 0.001
194 parameters
Δρmax = 0.58 e Å−3
0 restraints
Δρmin = −0.34 e Å−3
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.
Primary atom site location: structure-invariant direct methods
Least-squares matrix: full
Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052
Hydrogen site location: mixed
wR(F2) = 0.114
H atoms treated by a mixture of independent and constrained refinement
S = 1.12
w = 1/[σ2(Fo2) + (0.0062P)2 + 110.7865P] where P = (Fo2 + 2Fc2)/3
3936 reflections
(Δ/σ)max < 0.001
385 parameters
Δρmax = 0.78 e Å−3
6 restraints
Δρmin = −1.11 e Å−3
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.