research communications
Synthesis, cis-dichloridobis(oxalato-κ2O1,O2)stannate(IV)
and characterization by UV–Vis and IR spectroscopy of bis(diisopropylammonium)aLaboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Téchniques, Université Cheikh Anta Diop, Dakar, Senegal, bLaboratoire de Chimie et de Physique des Matériaux (LCPM) de l'Université Assane Seck de Ziguinchor (UASZ), BP 523 Ziguinchor, Senegal, and cICMUB-UMR 6302, 9, avenue Alain Savary 21000 Dijon, France
*Correspondence e-mail: bouks89@gmail.com
The organic–inorganic title salt, (C6H16N)2[Sn(C2O4)2Cl2] or (iPr2NH2)2[Sn(C2O4)2Cl2], was obtained by reacting bis(diisopropylammonium) oxalate with tin(IV) chloride dihydrate in methanol. The SnIV atom is coordinated by two chelating oxalate ligands and two chloride ions in cis positions, giving rise to an [Sn(C2O4)2Cl2]2− anion (point group symmetry 2), with the SnIV atom in a slightly distorted octahedral coordination. The cohesion of the is ensured by the formation of N—H⋯O hydrogen bonding between (iPr2NH2)+ cations and [SnCl2(C2O4)2]2− anions. This gives rise to an infinite chain structure extending parallel to [101]. The main inter-chain interactions are The electronic spectrum of the title compound displays only one high intensity band in the UV region assignable to ligand–metal ion charge-transfer (LMCT) transitions. An IR spectrum was also recorded and is discussed.
CCDC reference: 1833609
1. Chemical context
As a result of their numerous applications in medicine, industry and agriculture (Kapoor et al., 2005), tin(IV) carboxylate compounds have attracted the attention of several research groups, resulting in the preparation and characterization of new compounds (Christie et al., 1979; Ng & Kumar Das, 1993; Rocamora-Reverte et al., 2012; Reichelt & Reuter, 2014). Derivatives of tin(IV) oxalate are a subclass of the tin(IV) carboxylate family and have likewise been studied extensively because oxalate ions, C2O42–, play an important role as counter-ions or complex ligands in inorganic as well as in organometallic chemistry. One of the motivations to study these compounds is related to the rich coordinating behaviour of the oxalato ligand, which can adopt a monodentate, a bridging monodentate, a bridging bidentate, a monochelating, bidentate or a bichelating mode (Miskelly et al., 1983; Sow et al., 2012; Świtlicka-Olszewska et al., 2014). In this context, our group has previously published the syntheses and determinations of some tin(IV) oxalate derivatives (Sarr et al., 2013, 2018). As a continuation of this work, we have studied the interaction between bis(diisopropylammonium) oxalate with tin(IV) chloride dihydrate, which yielded the title salt (C6H16N)2[Sn(C2O4)2Cl2] or (iPr2NH2)2[Sn(C2O4)2Cl2]. Its was determined by single crystal X-ray diffraction and was confirmed by infrared and UV–visible spectroscopic studies.
2. Structural commentary
The iPr2NH2)2[Sn(C2O4)2Cl2] comprises one diisopropylammonium cation and one half of an [Sn(C2O4)2Cl2]2− anion, the other half being completed by the application of twofold rotation symmetry (Fig. 1) with the rotation axis running through the central SnIV atom. The latter is chelated by two oxalate ligands and is additionally ligated by two Cl atoms in cis positions within a distorted octahedral coordination sphere [Cl1i—Sn1—Cl1= 97.26 (4)°; O1—Sn1—O4 = O1i—Sn1—O4i = 79.27 (6) °, O1—Sn1—O4i = 90.21 (6)°; symmetry code: (i) x + , −y + , z − ]. Atoms Cl1i, O1, O1i and O4 define the equatorial plane [with a slight shift of Sn1 from this plane by 0.1163 (5) Å; rms = 0.0687 Å] while Cl1 and O4i occupy the axial positions. The O4i—Sn1—Cl1 angle of 168.50 (4)° indicates a considerable deviation from linearity, which might be explained by the difference in size of the Cl and O atoms and by the small bite angle of 79.27 (6)° between the central SnIV atom and the chelating O1 and O4 atoms.
of (As in the related structure of (iPr2NH2)2[Sn(C2O4)2I2] (Sarr et al., 2018), the lengths of the C—O bonds within the oxalate ligands vary slightly because of the different functions of the oxygen atoms involved in the coordination of SnIV. The C—O bond lengths of coordinating O atoms [O1—C7 = 1.289 (2) Å; O4—C8 = 1.289 (2) Å] are significantly longer than those of non-coordinating O atoms [O2—C7 = 1.222 (2) Å, O3—C8 = 1.223 (2) Å]. The Sn1—C1l distance of 2.3422 (9) Å as well as the Sn—O distances of 2.0710 (16) Å (O1) and of 2.1057 (15) Å (O4) are slightly shorter than corresponding bonds reported previously (Reichelt & Reuter, 2014; Sarr et al., 2013; Diop et al., 2011; Sow et al., 2013; Skapski et al., 1974).
3. Supramolecular features
Each anionic complex [Sn(C2O4)2Cl2]2– is linked to two neighbours via four diisopropylammonium cations through N—H⋯O hydrogen bonds, leading to infinite chains parallel to [101] (Table 1, Fig. 2). In a chain, the two non-coordinating oxygen atoms (O2 and O3) of each oxalate ligand are involved as acceptors in hydrogen-bonding interactions (Table 1). The chains are arranged into layers extending parallel to (010), mainly interconnected by (Fig. 3).
4. Database survey
A search in the Cambridge Structural Database (CSD, version 5.40, update Nov. 2018; Groom et al., 2016) resulted in 226 hits dealing with diisopropylammonium cations while only one hit deals with the [Sn(C2O4)2Cl2]2– anion (Sarr et al., 2013).
5. Synthesis and crystallization
The title salt was obtained by mixing bis(diisopropylammonium) oxalate (iPr2NH2)2C2O4; 0.30 g; 15.50 mmol) and tin(IV) chloride dihydrate (SnCl2·2H2O; (0.34 g; 15.50 mmol) in a 1:1 molar ratio in methanol. The obtained yellow solution was stirred for one h and then filtered. Colourless prism-like crystals were obtained by slow evaporation of the filtrate over a period of ten days.
The IR spectrum confirms the presence of oxalate and diisopropylammonium groups in the title salt. In addition, the appearance of valence vibrations (–CO2) in the form of three bands shows that the oxalate ligands are not centrosymmetric, in agreement with the difference in the C—O bond lengths revealed by the X-ray study. Attributions of the vibrational bands of the title compound were made by comparison with previous studies (Sarr et al., 2018; Marinescu et al., 2002; Li et al., 2008). The vibrational bands at 3061 and 1579 cm−1 in the IR spectrum (Fig. 4) are assigned to the stretching and deformation modes ν(N—H) and δ(N—H), respectively, of –NH2– in the ammonium group. The bands at 1675, 1375 and 1251 cm−1 are attributed to the asymmetric and symmetric vibrations of the oxalate –CO2 moiety while that at 795 cm−1 corresponds to the deformation vibrations δ(C—O) (Sarr et al., 2018; Marinescu et al., 2002; Li et al., 2008). The frequencies of stretching vibrations of the oxalate group often show slight deviations owing to the different coordination modes. The bands at 2882 cm−1 are assigned to the valence vibrations ν(C—H) and those at 1486 cm−1 to the deformation vibrations δ(C—H).
The electronic spectrum of the title compound is shown in Fig. 5. In the ultraviolet region, only one strong absorption band with a shoulder is observed. Generally, only π→π*, n→π* and LMCT transitions can be observed in the ultraviolet–visible (UV–Vis) region. The σ→σ* transition requires an absorption of a photon with a wavelength which does not fall in the UV–Vis range. Thus, this strong absorption band at 320 nm (Fig. 5) may be assigned to ligand-metal ion charge transfer (LMCT) (Kane et al., 2016). However, as the ligand-based π→π* / n→π* transitions absorb in the same area as the LMCT transitions, we cannot exclude a possibility of superposition of these transitions (ligand-based and LMCT) owing to the form of the absorption band (Ford & Vogler, 1993; Filho et al., 2000). In the title compound, the SnIV atom is surrounded by electron rich ligands (chlorido and oxalato), and π→π* and n→π* transitions may result from the non-binding electron pairs present on chlorine atoms or oxygen atoms of oxalate (Wojciechowska et al., 2016).
6. details
Crystal data, data collection and structure . All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with a N—H distance of 0.91 Å, Cmethyl—H = 0.98 Å and Cmethine = 1.0 Å, and with Uiso(H) = 1.2Ueq (C,N) or 1.5Ueq(Cmethyl). Three reflections were omitted from because they were obstructed by the beam stop.
details are summarized in Table 2Supporting information
CCDC reference: 1833609
https://doi.org/10.1107/S2056989019006030/wm5500sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019006030/wm5500Isup2.hkl
Data collection: APEX3 (Bruker, 2015); cell
SAINT (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).(C6H16N)2[Sn(C2ClO4)2] | F(000) = 1160 |
Mr = 570.02 | Dx = 1.558 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 16.275 (8) Å | Cell parameters from 7290 reflections |
b = 13.581 (6) Å | θ = 3.0–27.5° |
c = 11.116 (4) Å | µ = 1.31 mm−1 |
β = 98.40 (3)° | T = 100 K |
V = 2430.7 (18) Å3 | Plate, clear light colourless |
Z = 4 | 0.56 × 0.30 × 0.22 mm |
Bruker D8 VENTURE diffractometer | 2800 independent reflections |
Radiation source: X-ray tube, Siemens KFF Mo 2K-90C | 2597 reflections with I > 2σ(I) |
TRIUMPH curved crystal monochromator | Rint = 0.023 |
Detector resolution: 1024 pixels mm-1 | θmax = 27.5°, θmin = 3.0° |
φ and ω scans' | h = −20→21 |
Absorption correction: multi-scan (SADABS; Bruker, 2015) | k = −17→17 |
Tmin = 0.626, Tmax = 0.746 | l = −14→14 |
14360 measured reflections |
Refinement on F2 | Primary atom site location: dual |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.023 | H-atom parameters constrained |
wR(F2) = 0.055 | w = 1/[σ2(Fo2) + (0.011P)2 + 6.1885P] where P = (Fo2 + 2Fc2)/3 |
S = 1.28 | (Δ/σ)max = 0.002 |
2800 reflections | Δρmax = 1.01 e Å−3 |
136 parameters | Δρmin = −0.59 e Å−3 |
0 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
Sn1 | 0.5000 | 0.67465 (2) | 0.7500 | 0.01307 (6) | |
Cl1 | 0.55290 (4) | 0.56066 (4) | 0.89962 (5) | 0.02556 (12) | |
O1 | 0.38232 (9) | 0.69379 (11) | 0.79635 (12) | 0.0158 (3) | |
O2 | 0.31479 (8) | 0.77413 (11) | 0.92602 (12) | 0.0165 (3) | |
O3 | 0.46345 (9) | 0.85537 (11) | 1.03026 (12) | 0.0159 (3) | |
O4 | 0.52285 (9) | 0.78744 (10) | 0.88059 (12) | 0.0147 (3) | |
C7 | 0.37835 (11) | 0.75429 (14) | 0.88463 (16) | 0.0117 (3) | |
C8 | 0.46144 (11) | 0.80483 (14) | 0.93878 (17) | 0.0121 (4) | |
N1 | 0.82801 (10) | 0.66470 (12) | 0.67738 (14) | 0.0117 (3) | |
H1A | 0.8640 | 0.6618 | 0.6220 | 0.014* | |
H1B | 0.7824 | 0.6983 | 0.6421 | 0.014* | |
C1 | 0.80130 (13) | 0.56088 (15) | 0.70045 (19) | 0.0180 (4) | |
H1 | 0.7608 | 0.5626 | 0.7599 | 0.022* | |
C2 | 0.87571 (16) | 0.49960 (18) | 0.7530 (2) | 0.0317 (6) | |
H2A | 0.8580 | 0.4317 | 0.7643 | 0.048* | |
H2B | 0.9003 | 0.5271 | 0.8316 | 0.048* | |
H2C | 0.9170 | 0.5004 | 0.6970 | 0.048* | |
C3 | 0.75809 (16) | 0.52045 (17) | 0.5802 (2) | 0.0268 (5) | |
H3A | 0.7113 | 0.5632 | 0.5490 | 0.040* | |
H3B | 0.7376 | 0.4539 | 0.5926 | 0.040* | |
H3C | 0.7975 | 0.5181 | 0.5215 | 0.040* | |
C4 | 0.86854 (12) | 0.72450 (16) | 0.78415 (18) | 0.0163 (4) | |
H4 | 0.9228 | 0.6934 | 0.8176 | 0.020* | |
C5 | 0.88477 (14) | 0.82664 (16) | 0.7363 (2) | 0.0225 (4) | |
H5A | 0.9179 | 0.8209 | 0.6698 | 0.034* | |
H5B | 0.9151 | 0.8662 | 0.8020 | 0.034* | |
H5C | 0.8317 | 0.8586 | 0.7063 | 0.034* | |
C6 | 0.81368 (14) | 0.72851 (18) | 0.88350 (19) | 0.0231 (5) | |
H6A | 0.7582 | 0.7518 | 0.8491 | 0.035* | |
H6B | 0.8380 | 0.7738 | 0.9476 | 0.035* | |
H6C | 0.8094 | 0.6626 | 0.9179 | 0.035* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sn1 | 0.01120 (10) | 0.01596 (10) | 0.01279 (10) | 0.000 | 0.00420 (6) | 0.000 |
Cl1 | 0.0335 (3) | 0.0221 (3) | 0.0217 (2) | 0.0028 (2) | 0.0062 (2) | 0.0098 (2) |
O1 | 0.0111 (6) | 0.0235 (7) | 0.0134 (6) | −0.0049 (6) | 0.0037 (5) | −0.0063 (6) |
O2 | 0.0099 (6) | 0.0262 (8) | 0.0139 (7) | −0.0022 (6) | 0.0035 (5) | −0.0046 (6) |
O3 | 0.0147 (7) | 0.0193 (7) | 0.0130 (6) | −0.0013 (6) | 0.0001 (5) | −0.0048 (5) |
O4 | 0.0138 (7) | 0.0166 (7) | 0.0146 (7) | −0.0011 (5) | 0.0056 (5) | −0.0016 (5) |
C7 | 0.0112 (8) | 0.0143 (9) | 0.0095 (8) | −0.0013 (7) | 0.0009 (7) | 0.0026 (7) |
C8 | 0.0088 (8) | 0.0143 (9) | 0.0125 (8) | −0.0005 (7) | −0.0008 (7) | 0.0032 (7) |
N1 | 0.0115 (7) | 0.0134 (8) | 0.0100 (7) | 0.0003 (6) | 0.0013 (6) | 0.0021 (6) |
C1 | 0.0200 (10) | 0.0132 (9) | 0.0211 (10) | −0.0016 (8) | 0.0040 (8) | 0.0049 (8) |
C2 | 0.0323 (13) | 0.0207 (11) | 0.0403 (14) | 0.0066 (10) | −0.0010 (11) | 0.0129 (10) |
C3 | 0.0327 (13) | 0.0165 (10) | 0.0312 (12) | −0.0058 (9) | 0.0042 (10) | −0.0029 (9) |
C4 | 0.0118 (9) | 0.0227 (10) | 0.0131 (9) | −0.0002 (8) | −0.0030 (7) | −0.0018 (8) |
C5 | 0.0213 (11) | 0.0208 (10) | 0.0246 (11) | −0.0058 (9) | 0.0006 (8) | −0.0019 (9) |
C6 | 0.0250 (11) | 0.0294 (12) | 0.0144 (10) | 0.0001 (9) | 0.0016 (8) | −0.0015 (8) |
Sn1—Cl1 | 2.3422 (9) | C1—C3 | 1.519 (3) |
Sn1—Cl1i | 2.3422 (9) | C2—H2A | 0.9800 |
Sn1—O1 | 2.0710 (16) | C2—H2B | 0.9800 |
Sn1—O1i | 2.0711 (16) | C2—H2C | 0.9800 |
Sn1—O4i | 2.1057 (15) | C3—H3A | 0.9800 |
Sn1—O4 | 2.1058 (15) | C3—H3B | 0.9800 |
O1—C7 | 1.289 (2) | C3—H3C | 0.9800 |
O2—C7 | 1.222 (2) | C4—H4 | 1.0000 |
O3—C8 | 1.223 (2) | C4—C5 | 1.523 (3) |
O4—C8 | 1.289 (2) | C4—C6 | 1.519 (3) |
C7—C8 | 1.557 (3) | C5—H5A | 0.9800 |
N1—H1A | 0.9100 | C5—H5B | 0.9800 |
N1—H1B | 0.9100 | C5—H5C | 0.9800 |
N1—C1 | 1.508 (3) | C6—H6A | 0.9800 |
N1—C4 | 1.508 (2) | C6—H6B | 0.9800 |
C1—H1 | 1.0000 | C6—H6C | 0.9800 |
C1—C2 | 1.514 (3) | ||
Cl1i—Sn1—Cl1 | 97.26 (4) | C2—C1—C3 | 112.4 (2) |
O1—Sn1—Cl1 | 99.42 (5) | C3—C1—H1 | 109.0 |
O1—Sn1—Cl1i | 90.13 (5) | C1—C2—H2A | 109.5 |
O1i—Sn1—Cl1 | 90.13 (5) | C1—C2—H2B | 109.5 |
O1i—Sn1—Cl1i | 99.42 (5) | C1—C2—H2C | 109.5 |
O1—Sn1—O1i | 165.59 (8) | H2A—C2—H2B | 109.5 |
O1—Sn1—O4 | 79.27 (6) | H2A—C2—H2C | 109.5 |
O1—Sn1—O4i | 90.21 (6) | H2B—C2—H2C | 109.5 |
O1i—Sn1—O4i | 79.27 (6) | C1—C3—H3A | 109.5 |
O1i—Sn1—O4 | 90.21 (6) | C1—C3—H3B | 109.5 |
O4i—Sn1—Cl1 | 168.50 (4) | C1—C3—H3C | 109.5 |
O4—Sn1—Cl1i | 168.49 (4) | H3A—C3—H3B | 109.5 |
O4i—Sn1—Cl1i | 88.95 (5) | H3A—C3—H3C | 109.5 |
O4—Sn1—Cl1 | 88.95 (5) | H3B—C3—H3C | 109.5 |
O4i—Sn1—O4 | 86.66 (8) | N1—C4—H4 | 109.0 |
C7—O1—Sn1 | 114.87 (12) | N1—C4—C5 | 107.09 (16) |
C8—O4—Sn1 | 114.04 (12) | N1—C4—C6 | 110.83 (17) |
O1—C7—C8 | 115.98 (16) | C5—C4—H4 | 109.0 |
O2—C7—O1 | 124.51 (18) | C6—C4—H4 | 109.0 |
O2—C7—C8 | 119.50 (17) | C6—C4—C5 | 111.83 (18) |
O3—C8—O4 | 126.25 (18) | C4—C5—H5A | 109.5 |
O3—C8—C7 | 119.01 (17) | C4—C5—H5B | 109.5 |
O4—C8—C7 | 114.74 (16) | C4—C5—H5C | 109.5 |
H1A—N1—H1B | 107.1 | H5A—C5—H5B | 109.5 |
C1—N1—H1A | 107.7 | H5A—C5—H5C | 109.5 |
C1—N1—H1B | 107.7 | H5B—C5—H5C | 109.5 |
C4—N1—H1A | 107.7 | C4—C6—H6A | 109.5 |
C4—N1—H1B | 107.7 | C4—C6—H6B | 109.5 |
C4—N1—C1 | 118.25 (15) | C4—C6—H6C | 109.5 |
N1—C1—H1 | 109.0 | H6A—C6—H6B | 109.5 |
N1—C1—C2 | 110.20 (18) | H6A—C6—H6C | 109.5 |
N1—C1—C3 | 107.23 (16) | H6B—C6—H6C | 109.5 |
C2—C1—H1 | 109.0 | ||
Sn1—O1—C7—O2 | −178.95 (15) | O2—C7—C8—O3 | 7.8 (3) |
Sn1—O1—C7—C8 | 1.7 (2) | O2—C7—C8—O4 | −172.75 (17) |
Sn1—O4—C8—O3 | 168.18 (16) | C1—N1—C4—C5 | −177.16 (17) |
Sn1—O4—C8—C7 | −11.23 (19) | C1—N1—C4—C6 | −54.9 (2) |
O1—C7—C8—O3 | −172.83 (17) | C4—N1—C1—C2 | −60.8 (2) |
O1—C7—C8—O4 | 6.6 (2) | C4—N1—C1—C3 | 176.56 (17) |
Symmetry code: (i) −x+1, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O3ii | 0.91 | 2.05 | 2.943 (2) | 167 |
N1—H1B···O2i | 0.91 | 1.95 | 2.855 (2) | 177 |
Symmetry codes: (i) −x+1, y, −z+3/2; (ii) x+1/2, −y+3/2, z−1/2. |
Acknowledgements
The authors thank the Université Cheikh Anta Diop Dakar-Sénégal, the Laboratoire de Chimie et de Physique des Matériaux (LCPM) de l'Université Assane Seck de Ziguinchor, Sénégal and the ICMUB-UMR 6302, 9, avenue Alain Savary 21000 Dijon-France for financial support. All measurements were performed in the institutes quoted above. The authors also acknowledge the CNRS-Université de Strasbourg, France, through collaboration with Frederic Melin.
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