research communications
of bis(diisopropylammonium) molybdate
aLaboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Téchniques, Université Cheikh Anta Diop, Dakar, Senegal, bLaboratoire de Chimie et Physique des Matériaux (LCPM) de l'Université Assane Seck de Ziguinchor (UASZ), BP: 523 Ziguinchor, Senegal, cChimie de la Matière Complexe UMR 7140, Laboratoire de Bioélectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France, and dICMUB-UMR 6302, 9 avenue Alain Savary, 21000 Dijon, France
*Correspondence e-mail: bouks89@gmail.com
The organic–inorganic title salt, (C6H16N)2[MoO4] or (iPr2NH2)2[MoO4], was obtained by reacting MoO3 with diisopropylamine in a 1:2 molar ratio in water. The molybdate anion is located on a twofold rotation axis and exhibits a slightly distorted tetrahedral configuration. In the the diisopropylammmonium (iPr2NH2)+ cations and [MoO4]2− anions are linked to each other through N—H⋯O hydrogen bonds, generating rings with R1212(36) motifs that give rise to the formation of a three-dimensional network. The structure was refined taking into account inversion (ratio of ca 4:1 between the two domains).
Keywords: crystal structure; organic-inorganic salt; molybdate anion; N—H⋯O hydrogen bonding; graph set notation.
CCDC reference: 1874215
1. Chemical context
As a result of the photochromic properties of alkylammonium molybdates (Arnaud-Neu & Schwing-Weill, 1974), molybdenum chemistry is an exciting research area. A large variety of oxidoanions based on molybdenum have been synthesized and characterized with numerous counter-cations. Among these, mononuclear and binuclear anions as well as polyoxidomolybdates with a much higher nuclearity are known (Gatehouse & Leverett, 1969; Matsumoto et al. 1975; Modec et al., 2004; Müller & Gouzerh, 2012; Pouye et al., 2014; Sarr et al., 2018). Salts containing the tetrahedral molybdate anion [MoO4]2– combined with cations such as K+, Na+, (CH6N3)+, ((C6H11)2NH2)+, (NH3(CH2)2NH3)+, (OHRNH3)+ and (CyNH2)+ have been isolated in the past (Gatehouse & Leverett, 1969; Matsumoto et al., 1975; Ozeki et al., 1987; Thiele & Fuchs, 1979; Bensch et al., 1987; Sheikhshoaie & Ghazizadeh, 2013; Pouye et al., 2014), but never with the diisopropylammonium cation (iPr2NH2)+. In a continuation of our work on molybdenum compounds with organic cations, we report here the synthesis and of the title compound, (iPr2NH2)2[MoO4], (I).
2. Structural commentary
The comprises one (iPr2NH2)+ cation and an {MoO2} entity (Fig. 1). The [MoO4]2– molybdate anion is completed by application of twofold rotation symmetry. The two Mo—O distances are 1.732 (2) and 1.7505 (15) Å and the O—Mo—O angles vary in a narrow range between 108.77 (10) and 110.7 (2)° (Table 1), revealing only slight distortions from ideal values. Similar bond lengths and angles for the molybdate anion were reported in previous studies (Ozeki et al., 1987; Bensch et al., 1987; Sheikhshoaie & Ghazizadeh, 2013; Pouye et al., 2014) where the Mo—O distances vary between 1.749 (2) and 1.776 (3) Å, and the O—Mo—O angles between 106.85 (4) and 113.2 (1)°.
of (I)
|
In the 2)2MoO4·2H2O (Cy = cyclohexyl; Pouye et al., 2014) the four Mo—O bond lengths are equal with 1.7613 (12) Å. Although in this structure similar N—H⋯O intermolecular interactions between the (CyNH2)+ cation and the molybdate anion are present in comparison with the (iPr2NH2)+ cation in the title compound, the small differences in the hydrogen-bonding pattern result in slightly different Mo—O bond lengths between the two structures. On one hand this may be related to the presence of additional water molecules in (CyNH2)2MoO4·2H2O, on the other hand to between the four diisopropylammonium cations that surround each molybdate anion in (I). At least the strengths of the N—H⋯O hydrogen bonds do not seem to have a noticeable effect on the different Mo—O distances in (I). Both hydrogen bonds are very similar in terms of N⋯O distances and N—H⋯O angles (Table 2).
of (CyNH3. Supramolecular features
In the , each [MoO4]2– anion is linked to two pairs of symmetry-related diisopropylammonium cations through N—H⋯O hydrogen bonds (Table 2). Contrariwise, each (iPr2NH2)+ cation is linked to two molybdate [MoO4]2− anions. The interaction of six molybdate anions with six diisopropylammonium cations leads to {(iPr2NH2)⋯MoO4}6 ring systems with an R1212(36) motif (Etter et al., 1990). Each ring is linked to six adjacent rings giving rise to infinite layers extending parallel to (010) (Fig. 2). The connection of the rings into a three-dimensional network structure perpendicular to this plane is shown in Fig. 3.
of (I)4. Database survey
A search of the Cambridge Structural Database (Version 5.39 plus 1 update, November 2017; Groom et al., 2016) revealed 226 entries dealing with (iPr2NH2)+ cations while 32 entries contained the [MoO4]2− molybdate anion.
5. Synthesis and crystallization
Compound (I) was obtained from a mixture of molybdenum trioxide (3.2 g, 22.23 mmol) and diisopropylamine (4 g, 44.46 mmol) in a 1:2 molar ratio in water. A clear, colourless solution was obtained after stirring for approximately one h. After twenty days of evaporation in an oven at 333 K, some colourless single crystals were obtained.
In the IR spectrum of (I) (Fig. 4a), the bands at 899 and 786 cm−1 can be attributed to symmetric and asymmetric Mo—O stretching modes, respectively. The disopropylammonium cation is characterized by a series of vibrational bands in the 3000–2200 cm−1 region, which can be attributed to ν(N—H), ν(C—H) and combination modes. The δ(N—H) bending vibrations probably contribute to the signal observed at 1598 cm−1.
In the Raman spectrum of (I) (Fig. 4b), the band at 797 cm−1 is attributed to the antisymmetric stretching mode of the [MoO4]2− molybdate anion. The symmetric vibration, νs(Mo—O), in the form of a weak shoulder at 839 cm−1 in the infrared spectrum, is very intense in the Raman spectrum at 896 cm−1. In the high wavenumber region of the Raman spectrum, the bands between 3000 and 2800 cm−1 can be assigned to the ν(N—H) and ν(C—H) stretching vibrations of the diisopropylammonium cation.
6. Refinement
Crystal data, data collection and structure . The structure was refined taking into account (ratio of ca 4:1 between the two domains). H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with N—H distances of 0.89 Å and C—H distances of 0.96 Å for methyl and of 0.98 Å for methylene groups, and with Uiso(H) = 1.2Ueq(C,N) or 1.5Ueq(Cmethyl).
details are summarized in Table 3Supporting information
CCDC reference: 1874215
Data collection: CrysAlis PRO (Rigaku OD, 2015); cell
CrysAlis PRO (Rigaku OD, 2015); data reduction: CrysAlis PRO (Rigaku OD, 2015); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).(C6H16N)2[MoO4] | Dx = 1.288 Mg m−3 |
Mr = 364.33 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, P43212 | Cell parameters from 49023 reflections |
a = 9.0166 (1) Å | θ = 3.6–27.7° |
c = 23.1158 (3) Å | µ = 0.71 mm−1 |
V = 1879.29 (5) Å3 | T = 293 K |
Z = 4 | Prism, clear light colourless |
F(000) = 768 | 0.38 × 0.26 × 0.1 mm |
Rigaku Oxford Diffraction SuperNova, Dual, Cu at zero, AtlasS2 diffractometer | 2109 reflections with I > 2σ(I) |
Detector resolution: 5.3048 pixels mm-1 | Rint = 0.055 |
ω scans | θmax = 27.5°, θmin = 3.5° |
Absorption correction: multi-scan (CrysAlis PRO; Rigaku OD, 2015) | h = −11→11 |
Tmin = 0.612, Tmax = 1.000 | k = −11→11 |
111277 measured reflections | l = −29→30 |
2156 independent reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.019 | w = 1/[σ2(Fo2) + (0.0245P)2 + 0.4149P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.049 | (Δ/σ)max < 0.001 |
S = 1.12 | Δρmax = 0.21 e Å−3 |
2156 reflections | Δρmin = −0.31 e Å−3 |
92 parameters | Absolute structure: Refined as an inversion twin |
0 restraints | Absolute structure parameter: 0.19 (7) |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Refined as a 2-component inversion twin. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.6950 (2) | 0.2985 (3) | 0.57328 (7) | 0.0451 (5) | |
H1A | 0.607999 | 0.280281 | 0.556562 | 0.054* | |
H1B | 0.681809 | 0.289840 | 0.611289 | 0.054* | |
C1 | 0.8015 (3) | 0.1790 (4) | 0.55462 (12) | 0.0603 (7) | |
H1 | 0.897057 | 0.196363 | 0.573616 | 0.072* | |
C2 | 0.7411 (5) | 0.0325 (4) | 0.57499 (18) | 0.0827 (10) | |
H2A | 0.725309 | 0.036136 | 0.616035 | 0.124* | |
H2B | 0.810811 | −0.044698 | 0.566106 | 0.124* | |
H2C | 0.648792 | 0.012618 | 0.555832 | 0.124* | |
C3 | 0.8245 (4) | 0.1852 (5) | 0.48930 (13) | 0.0872 (11) | |
H3A | 0.731448 | 0.169286 | 0.470093 | 0.131* | |
H3B | 0.893498 | 0.109574 | 0.477926 | 0.131* | |
H3C | 0.863030 | 0.280735 | 0.478768 | 0.131* | |
C4 | 0.7349 (4) | 0.4560 (3) | 0.56091 (11) | 0.0590 (7) | |
H4 | 0.745520 | 0.468318 | 0.518986 | 0.071* | |
C5 | 0.8813 (4) | 0.4960 (4) | 0.58963 (15) | 0.0750 (10) | |
H5A | 0.876969 | 0.471035 | 0.629966 | 0.112* | |
H5B | 0.899069 | 0.600390 | 0.585479 | 0.112* | |
H5C | 0.960302 | 0.441624 | 0.571562 | 0.112* | |
C6 | 0.6069 (4) | 0.5518 (4) | 0.58154 (14) | 0.0735 (10) | |
H6A | 0.518209 | 0.524379 | 0.561190 | 0.110* | |
H6B | 0.628992 | 0.654184 | 0.574169 | 0.110* | |
H6C | 0.592529 | 0.537236 | 0.622295 | 0.110* | |
Mo1 | 0.26396 (2) | 0.26396 (2) | 0.500000 | 0.03021 (9) | |
O1 | 0.2086 (2) | 0.1625 (2) | 0.43916 (6) | 0.0510 (5) | |
O2 | 0.4506 (2) | 0.2317 (4) | 0.51236 (10) | 0.0959 (9) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0337 (9) | 0.0747 (15) | 0.0269 (8) | 0.0005 (9) | −0.0009 (7) | −0.0005 (9) |
C1 | 0.0350 (13) | 0.095 (2) | 0.0510 (15) | 0.0047 (13) | 0.0011 (11) | −0.0167 (15) |
C2 | 0.069 (2) | 0.075 (2) | 0.104 (3) | 0.006 (2) | 0.010 (2) | −0.016 (2) |
C3 | 0.070 (2) | 0.138 (3) | 0.0536 (17) | 0.007 (2) | 0.0170 (16) | −0.026 (2) |
C4 | 0.0638 (19) | 0.0767 (18) | 0.0364 (12) | −0.0047 (17) | −0.0013 (14) | 0.0133 (12) |
C5 | 0.064 (2) | 0.083 (3) | 0.078 (2) | −0.0223 (18) | −0.0017 (18) | 0.003 (2) |
C6 | 0.086 (2) | 0.071 (2) | 0.0631 (18) | 0.0121 (18) | −0.0156 (17) | 0.0083 (17) |
Mo1 | 0.03380 (10) | 0.03380 (10) | 0.02304 (12) | −0.00356 (9) | −0.00072 (6) | 0.00072 (6) |
O1 | 0.0687 (12) | 0.0566 (10) | 0.0277 (7) | −0.0072 (9) | −0.0063 (7) | −0.0049 (7) |
O2 | 0.0350 (9) | 0.178 (3) | 0.0751 (14) | 0.0026 (14) | −0.0119 (9) | −0.0308 (18) |
N1—H1A | 0.8900 | C4—H4 | 0.9800 |
N1—H1B | 0.8900 | C4—C5 | 1.521 (5) |
N1—C1 | 1.506 (4) | C4—C6 | 1.518 (5) |
N1—C4 | 1.493 (4) | C5—H5A | 0.9600 |
C1—H1 | 0.9800 | C5—H5B | 0.9600 |
C1—C2 | 1.504 (5) | C5—H5C | 0.9600 |
C1—C3 | 1.525 (4) | C6—H6A | 0.9600 |
C2—H2A | 0.9600 | C6—H6B | 0.9600 |
C2—H2B | 0.9600 | C6—H6C | 0.9600 |
C2—H2C | 0.9600 | Mo1—O1 | 1.7505 (15) |
C3—H3A | 0.9600 | Mo1—O1i | 1.7504 (15) |
C3—H3B | 0.9600 | Mo1—O2 | 1.732 (2) |
C3—H3C | 0.9600 | Mo1—O2i | 1.732 (2) |
H1A—N1—H1B | 107.1 | N1—C4—H4 | 108.7 |
C1—N1—H1A | 107.8 | N1—C4—C5 | 110.5 (2) |
C1—N1—H1B | 107.8 | N1—C4—C6 | 107.3 (3) |
C4—N1—H1A | 107.8 | C5—C4—H4 | 108.7 |
C4—N1—H1B | 107.8 | C6—C4—H4 | 108.7 |
C4—N1—C1 | 118.2 (2) | C6—C4—C5 | 112.9 (3) |
N1—C1—H1 | 108.5 | C4—C5—H5A | 109.5 |
N1—C1—C3 | 110.1 (3) | C4—C5—H5B | 109.5 |
C2—C1—N1 | 108.0 (3) | C4—C5—H5C | 109.5 |
C2—C1—H1 | 108.5 | H5A—C5—H5B | 109.5 |
C2—C1—C3 | 113.0 (3) | H5A—C5—H5C | 109.5 |
C3—C1—H1 | 108.5 | H5B—C5—H5C | 109.5 |
C1—C2—H2A | 109.5 | C4—C6—H6A | 109.5 |
C1—C2—H2B | 109.5 | C4—C6—H6B | 109.5 |
C1—C2—H2C | 109.5 | C4—C6—H6C | 109.5 |
H2A—C2—H2B | 109.5 | H6A—C6—H6B | 109.5 |
H2A—C2—H2C | 109.5 | H6A—C6—H6C | 109.5 |
H2B—C2—H2C | 109.5 | H6B—C6—H6C | 109.5 |
C1—C3—H3A | 109.5 | O1i—Mo1—O1 | 110.33 (12) |
C1—C3—H3B | 109.5 | O2i—Mo1—O1 | 109.13 (11) |
C1—C3—H3C | 109.5 | O2—Mo1—O1i | 109.13 (11) |
H3A—C3—H3B | 109.5 | O2—Mo1—O1 | 108.77 (10) |
H3A—C3—H3C | 109.5 | O2i—Mo1—O1i | 108.77 (10) |
H3B—C3—H3C | 109.5 | O2i—Mo1—O2 | 110.7 (2) |
C1—N1—C4—C5 | −59.1 (3) | C4—N1—C1—C2 | 176.6 (2) |
C1—N1—C4—C6 | 177.5 (2) | C4—N1—C1—C3 | −59.5 (3) |
Symmetry code: (i) y, x, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O2 | 0.89 | 1.80 | 2.684 (3) | 170 |
N1—H1B···O1ii | 0.89 | 1.81 | 2.695 (2) | 174 |
Symmetry code: (ii) y+1/2, −x+1/2, z+1/4. |
Acknowledgements
The authors thank the Université Cheikh Anta Diop, Dakar, Sénégal, the Laboratoire de Chimie et Physique des Matériaux (LCPM) de l'Université Assane Seck de Ziguinchor, Sénégal, the CNRS and Université de Strasbourg, France, the Aix Marseille Univ, CNRS, Centrale Marseille, FSCM, Spectropole, Marseille, France and the ICMUB-UMR 6302, Dijon, France for financial support.
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