Crystal structure of hy­droxy scandium nitrate chloride

Sears, J.; Cramer, R.; Boyle, T.

doi:10.1107/S2056989019003918

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Volume 75| Part 5| May 2019| Pages 540-542

https://doi.org/10.1107/S2056989019003918

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Crystal structure of hydroxy scandium nitrate chloride

Jeremiah Sears,^a Roger Cramer ^b and Timothy Boyle ^a ^*

^aSandia National Laboratories, Advanced Materials Laboratory, 1001 University, Boulevard, SE, Albuquerque, NM 87106, USA, and ^bUniversity of Hawaii - Manoa, Department of Chemistry, 2545 McCarthy Mall, Honolulu, HI 96822-2275, USA
^*Correspondence e-mail: tjboyle@sandia.gov

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 26 April 2018; accepted 21 March 2019; online 2 April 2019)

Each Sc³⁺ ion in the title salt, di-μ-hydroxido-bis[triaqua(nitrato-κ²O,O′)scandium(III)] dichloride, [Sc₂(NO₃)₂(OH)₂(H₂O)₆]Cl₂, is coordinated by a nitrate anion, two hydroxide ions and three water molecules to generate a distorted pentagonal–bipyramidal ScO₇ coordination polyhedron. The complete {[(NO₃)(μ-OH)Sc(H₂O)₃]₂}²⁺ ion is generated by crystallographic inversion symmetry. The nitrate anion binds in a bidentate fashion whereas the hydroxide ions are bridged between two Sc centers. Two charge-balancing Cl⁻ ions are located in the outer sphere. In the extended structure, O—H⋯O and O—H⋯Cl hydrogen bonds connect the components into a three-dimensional network.

Keywords: scandium; heptacoordinate; nitrate; crystal structure.

CCDC reference: 1904826

1. Chemical context

Scandium nitrate compounds have found widespread utility in a diverse number of applications, including catalysts for aqueous-based organic reactions (Kobayashi, 1999 ), heterogeneous Lewis acid catalysts (Cao et al., 2015 ), cyanosilylation catalysis (Zhang et al., 2015 ) and films for use in optics and electronic manufacturing (Wang et al., 2013 ). Previously, the structural properties of scandium salts were reviewed and the wide variety of structure types available for Sc metal were presented (Sears et al., 2017 ). From this review, the diversity of structurally characterized scandium nitrate salts was illuminated. These were found to possess inner-sphere, outer-sphere and mixed-sphere nitrate ions. Additionally, a number of bridging ligands (OH⁻, OMe⁻) were present. As we continue to explore the fundamental coordination behavior of scandium with nitric acid as a means to recycle this multipurpose metal, another unusual scandium nitrate structure [(κ²-NO₃)(μ-OH)Sc(H₂O)₃]₂2(Cl) (1) was isolated. This report details the structure and its relationship to known scandium nitrate derivatives.

2. Structural commentary

The title compound (Fig. 1) is the third reported hydrated scandium nitrate salt. We previously isolated [(H₂O)₄Sc(k²-NO₃)₂](NO₃)H₂O and [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃) from the reaction of [(H₂O)₅Sc(μ-OH)]₂4(Cl)2(H₂O) with concentrated nitric acid at elevated and room temperatures, respectively. Similarities between [(k²-NO₃)(μ-OH)Sc(H₂O)₃]₂2(Cl) and [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃) were expected and observed.

Figure 1
The molecular structure of the title compound, with non-H atoms shown as displacement ellipsoids at the 50% probability level. Only one Cl⁻ ion is shown. Unlabeled atoms are generated by the symmetry operation 1 − x, −y, 1 − z.

The axial water molecules are distorted from linearity more so for 1 [O1—Sc1—O4 = 166.48 (2)°] than for [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃) [O4—Sc—O6 = 171.52 (7)°]. The Sc—O (H₂O) bond distances of 2.124 (1)–2.148 (1) Å for 1 are comparable to the 2.114 (2)–2.183 (1) Å distances reported for the other hydroxide-bridged NO₃ salt. Bond angles between the axial water molecules and the remaining nearly coplanar equatorial ligands range from 79.56 (2)–100.60 (2)° for 1 and 82.50 (6)–99.96 (6)° for [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃). The angles between the equatorial oxygen atoms range from 55.61 (2)–81.36 (2)° and 55.76 (5)–83.70 (6)°, respectively. The shortest Sc—O bond distances, 2.0542 (5)–2.0569 (5) Å for 1 and 2.053 (2)–2.076 (1) Å for [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃), occur for the bridging hydroxide ions. In both salts, the bidentate NO₃ ions have the weakest interaction with Sc—O bond distances of 2.291 (1)–2.314 (1) Å for 1 and 2.114 (2)–2.183 (1) Å for [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃).

The precursor to 1, [(H₂O)₅Sc(μ-OH)]₂4(Cl)2(H₂O), is also a seven-coordinate Sc salt. Rotation of the precursor reveals a capped trigonal–prismatic geometry about the Sc centers that is useful for comparison. Equatorial ligand angles for [(H₂O)₅Sc(μ-OH)]₂4(Cl)2(H₂O) had a much smaller range of 83.32–95.17°. Dihedral angles between axial and equatorial ligands for the precursor also have a significantly reduced range of 77.18–79.09°. These differences further support the distorted pentagonal–bipyramidal geometry assigned to 1.

3. Supramolecular features

A network of scandium hydroxy nitrate dimer chains that interact via separate equatorial coordinated water molecules and nitrate ions with one another is observed for [(k²-NO₃)(μ-OH)Sc(H₂O)₃]₂2(Cl). These chains are further linked into a three-dimensional network (Fig. 2) by O—H⋯Cl hydrogen bonds between axially as well as equatorially coordinated water molecules and outer sphere Cl⁻ anions indicated by the symmetry operations in Table 1.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O6ⁱ	0.782 (16)	2.051 (16)	2.8175 (7)	166.6 (16)
O1—H1B⋯Cl1ⁱⁱ	0.787 (15)	2.300 (15)	3.0856 (6)	176.6 (14)
O2—H2⋯Cl1ⁱⁱⁱ	0.692 (16)	2.617 (16)	3.2749 (5)	159.7 (17)
O3—H3A⋯Cl1ⁱⁱⁱ	0.815 (16)	2.305 (16)	3.1017 (6)	165.9 (15)
O3—H3B⋯O5^iv	0.811 (15)	1.989 (15)	2.7977 (7)	175.0 (14)
O4—H4A⋯Cl1^v	0.859 (15)	2.316 (15)	3.1722 (6)	174.5 (13)
O4—H4B⋯Cl1	0.824 (16)	2.242 (16)	3.0658 (6)	179.0 (15)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) -x+1, -y, -z+1; (iii) x+1, y, z; (iv) -x+2, -y+1, -z+2; (v) -x+1, -y, -z+2.

Figure 2
Partial packing diagram of the title compound, showing hydrogen bonds as dashed lines.

4. Database survey

There are two reports of hydrated scandium nitrates, [(H₂O)₄Sc(k²-NO₃)₂](NO₃)(H₂O) (Boyle et al., 2015 ) and [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃) (Wang et al., 2013; Boyle et al. 2015), and both contain outer-sphere nitrate anions. As expected a similar network is observed for [(H₂O)₃Sc(k²-NO₃)(μ-OH)]₂2(NO₃). Salt 1 is the first reported hydrated scandium nitrate to contain outer-sphere chloride anions.

5. Synthesis and crystallization

Salt 1 was isolated from a cooled (273 K) mixture of [(H₂O)₅Sc(μ-OH)]₂4(Cl)2(H₂O) dissolved in water and an equal volume of concentrated HNO₃(aq). The reaction was slowly warmed to room temperature and set aside for slow evaporation until crystals formed. From this mixture, a single crystal of 1 was selected and used for single crystal X-ray analysis. Note: Both [(H₂O)₄Sc(κ²-NO₃)₂]NO₃(H₂O) and [(H₂O)₃Sc(κ²-NO₃)(μ-OH)]₂2(NO₃) have also been isolated from this preparatory route (Boyle et al., 2015).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	[Sc₂(NO₃)₂(OH)₂(H₂O)₆]2(Cl)
M_r	426.95
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	100
a, b, c (Å)	6.7221 (3), 7.6279 (4), 8.5181 (4)
α, β, γ (°)	100.904 (2), 110.125 (2), 102.329 (2)
V (Å³)	383.87 (3)
Z	1
Radiation type	Mo Kα
μ (mm⁻¹)	1.30
Crystal size (mm)	0.52 × 0.24 × 0.21

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2016)
T_min, T_max	0.634, 0.749
No. of measured, independent and observed [I > 2σ(I)] reflections	21806, 5393, 4597
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.944

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.024, 0.056, 1.04
No. of reflections	5393
No. of parameters	119
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.50, −0.35
Computer programs: APEX3 and SAINT (Bruker, 2016 ), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 1904826

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2056989019003918/hb4231sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019003918/hb4231Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); 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).

Di-µ-hydroxido-bis[triaqua(nitrato-κ²O,O')scandium(III)] dichloride top

Crystal data top

[Sc₂(NO₃)₂(OH)₂(H₂O)₆]2(Cl)	Z = 1
M_r = 426.95	F(000) = 216
Triclinic, P1	D_x = 1.847 Mg m⁻³
a = 6.7221 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.6279 (4) Å	Cell parameters from 9960 reflections
c = 8.5181 (4) Å	θ = 2.7–43.4°
α = 100.904 (2)°	µ = 1.30 mm⁻¹
β = 110.125 (2)°	T = 100 K
γ = 102.329 (2)°	Plate, colourless
V = 383.87 (3) Å³	0.52 × 0.24 × 0.21 mm

Data collection top

Bruker APEXII CCD diffractometer	4597 reflections with I > 2σ(I)
Radiation source: fine–focus tube	R_int = 0.025
φ and ω scans	θ_max = 42.1°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2016)	h = −12→12
T_min = 0.634, T_max = 0.749	k = −14→14
21806 measured reflections	l = −16→15
5393 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.024	All H-atom parameters refined
wR(F²) = 0.056	w = 1/[σ²(F_o²) + (0.026P)² + 0.0527P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.001
5393 reflections	Δρ_max = 0.50 e Å⁻³
119 parameters	Δρ_min = −0.35 e Å⁻³
0 restraints

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Sc1	0.64421 (2)	0.20102 (2)	0.65362 (2)	0.00619 (2)
O1	0.77577 (9)	0.34667 (7)	0.50248 (7)	0.01145 (8)
H1A	0.730 (3)	0.425 (2)	0.469 (2)	0.037 (4)*
H1B	0.814 (2)	0.297 (2)	0.4330 (19)	0.031 (4)*
O2	0.66804 (8)	−0.04815 (7)	0.53126 (6)	0.00944 (8)
H2	0.755 (3)	−0.084 (2)	0.562 (2)	0.042 (4)*
O3	0.97436 (9)	0.22378 (8)	0.82658 (7)	0.01256 (9)
H3A	1.025 (3)	0.136 (2)	0.832 (2)	0.036 (4)*
H3B	1.042 (2)	0.306 (2)	0.919 (2)	0.030 (4)*
O4	0.54719 (9)	0.11936 (8)	0.84788 (7)	0.01370 (9)
H4A	0.639 (2)	0.131 (2)	0.951 (2)	0.032 (4)*
H4B	0.425 (3)	0.048 (2)	0.829 (2)	0.037 (4)*
O5	0.77362 (8)	0.48678 (7)	0.86375 (7)	0.01144 (8)
O6	0.45946 (9)	0.42130 (7)	0.64820 (6)	0.01136 (8)
O7	0.57811 (11)	0.68156 (9)	0.85879 (8)	0.02282 (13)
N1	0.60275 (10)	0.53719 (8)	0.79388 (8)	0.01116 (9)
Cl1	0.09630 (3)	−0.14716 (2)	0.78189 (2)	0.01058 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sc1	0.00664 (4)	0.00485 (4)	0.00490 (4)	0.00172 (3)	0.00048 (3)	0.00005 (3)
O1	0.0153 (2)	0.0105 (2)	0.0118 (2)	0.00636 (17)	0.00710 (17)	0.00454 (16)
O2	0.00739 (17)	0.00762 (18)	0.00909 (18)	0.00341 (14)	−0.00061 (14)	−0.00082 (14)
O3	0.01049 (19)	0.00957 (19)	0.0107 (2)	0.00455 (16)	−0.00204 (16)	−0.00219 (16)
O4	0.0119 (2)	0.0173 (2)	0.00861 (19)	0.00022 (17)	0.00226 (16)	0.00464 (17)
O5	0.00943 (18)	0.00930 (19)	0.01084 (19)	0.00451 (15)	−0.00074 (15)	−0.00048 (15)
O6	0.01149 (19)	0.00946 (19)	0.00762 (18)	0.00380 (15)	−0.00085 (15)	−0.00164 (15)
O7	0.0229 (3)	0.0165 (3)	0.0196 (3)	0.0137 (2)	−0.0006 (2)	−0.0075 (2)
N1	0.0113 (2)	0.0094 (2)	0.0092 (2)	0.00476 (17)	0.00089 (17)	−0.00115 (17)
Cl1	0.01037 (6)	0.01118 (6)	0.01048 (6)	0.00477 (5)	0.00374 (5)	0.00283 (5)

Geometric parameters (Å, º) top

Sc1—O2	2.0542 (5)	O2—Sc1ⁱ	2.0569 (5)
Sc1—O2ⁱ	2.0569 (5)	O2—H2	0.692 (16)
Sc1—O4	2.1238 (6)	O3—H3A	0.815 (16)
Sc1—O1	2.1399 (5)	O3—H3B	0.811 (15)
Sc1—O3	2.1482 (5)	O4—H4A	0.859 (15)
Sc1—O6	2.2910 (5)	O4—H4B	0.824 (16)
Sc1—O5	2.3140 (5)	O5—N1	1.2752 (8)
Sc1—Sc1ⁱ	3.3085 (3)	O6—N1	1.2837 (8)
O1—H1A	0.782 (16)	O7—N1	1.2068 (8)
O1—H1B	0.787 (15)

O2—Sc1—O2ⁱ	72.83 (2)	O4—Sc1—Sc1ⁱ	95.494 (17)
O2—Sc1—O4	99.79 (2)	O1—Sc1—Sc1ⁱ	97.895 (16)
O2ⁱ—Sc1—O4	89.10 (2)	O3—Sc1—Sc1ⁱ	117.158 (16)
O2—Sc1—O1	92.12 (2)	O6—Sc1—Sc1ⁱ	114.024 (14)
O2ⁱ—Sc1—O1	100.60 (2)	O5—Sc1—Sc1ⁱ	168.016 (14)
O4—Sc1—O1	166.48 (2)	Sc1—O1—H1A	121.1 (11)
O2—Sc1—O3	81.36 (2)	Sc1—O1—H1B	122.4 (10)
O2ⁱ—Sc1—O3	152.16 (2)	H1A—O1—H1B	107.7 (15)
O4—Sc1—O3	85.12 (2)	Sc1—O2—Sc1ⁱ	107.17 (2)
O1—Sc1—O3	90.41 (2)	Sc1—O2—H2	125.6 (14)
O2—Sc1—O6	148.997 (19)	Sc1ⁱ—O2—H2	125.0 (14)
O2ⁱ—Sc1—O6	78.391 (19)	Sc1—O3—H3A	124.5 (11)
O4—Sc1—O6	90.93 (2)	Sc1—O3—H3B	122.1 (10)
O1—Sc1—O6	81.93 (2)	H3A—O3—H3B	108.8 (14)
O3—Sc1—O6	128.81 (2)	Sc1—O4—H4A	124.1 (10)
O2—Sc1—O5	154.887 (19)	Sc1—O4—H4B	125.0 (11)
O2ⁱ—Sc1—O5	131.997 (19)	H4A—O4—H4B	108.9 (14)
O4—Sc1—O5	79.56 (2)	N1—O5—Sc1	94.62 (4)
O1—Sc1—O5	86.94 (2)	N1—O6—Sc1	95.45 (4)
O3—Sc1—O5	73.561 (19)	O7—N1—O5	122.93 (6)
O6—Sc1—O5	55.610 (18)	O7—N1—O6	122.90 (6)
O2—Sc1—Sc1ⁱ	36.441 (14)	O5—N1—O6	114.17 (5)
O2ⁱ—Sc1—Sc1ⁱ	36.388 (14)

Sc1—O5—N1—O7	176.54 (7)	Sc1—O6—N1—O7	−176.50 (7)
Sc1—O5—N1—O6	−3.65 (6)	Sc1—O6—N1—O5	3.69 (6)

Symmetry code: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O6ⁱⁱ	0.782 (16)	2.051 (16)	2.8175 (7)	166.6 (16)
O1—H1B···Cl1ⁱ	0.787 (15)	2.300 (15)	3.0856 (6)	176.6 (14)
O2—H2···Cl1ⁱⁱⁱ	0.692 (16)	2.617 (16)	3.2749 (5)	159.7 (17)
O3—H3A···Cl1ⁱⁱⁱ	0.815 (16)	2.305 (16)	3.1017 (6)	165.9 (15)
O3—H3B···O5^iv	0.811 (15)	1.989 (15)	2.7977 (7)	175.0 (14)
O4—H4A···Cl1^v	0.859 (15)	2.316 (15)	3.1722 (6)	174.5 (13)
O4—H4B···Cl1	0.824 (16)	2.242 (16)	3.0658 (6)	179.0 (15)

Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+1, −y+1, −z+1; (iii) x+1, y, z; (iv) −x+2, −y+1, −z+2; (v) −x+1, −y, −z+2.

Funding information

This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the US Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

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