ACr(C₂O₄)₂(H₂O)₄ (A = Li or Na): two new coordination polymers of low dimensionality with different hydrogen-bond networks

Single crystals of two new bimetallic oxalate com­pounds with the formula [ACr(C₂O₄)₂(H₂O)₄]_n (A = Li or Na), namely catena-poly[[di­aqua­lithium(I)]-μ-oxalato-κ⁴O¹,O²:O^1′,O^2′-[di­aqua­chromium(III)]-μ-oxalato-κ⁴O¹,O²:O^1′,O^2′], (I), and catena-poly[[di­aqua­sodium(I)]-μ-oxalato-κ⁴O¹,O²:O^1′,O^2′-[di-aqua­chro­mium(III)]-μ-oxalato-κ⁴O¹,O²:O^1′,O^2′], (II), have been synthesized, characterized and their crystal structures elucidated by X-ray diffraction analysis and com­pared. The com­pounds crystallize in the monoclinic space group C2/m for (I) and in the triclinic space group P for (II); however, they have somewhat similar features. In the asymmetric unit of (I), the Li and Cr atoms both have space-group-imposed 2/m site symmetry, while only half of the oxalate ligand is present and two independent water mol­ecules lie on the mirror plane. The water O atoms around the Li atom are disordered over two equivalent positions separated by 0.54 (4) Å. In the asymmetric unit of (II), the atoms of one C₂O₄²⁻ ligand and two independent water mol­ecules are in general positions, and the Na and Cr atoms lie on an inversion centre. Taking into account the symmetry sites of both metallic elements, the unit cells may be described as pseudo-face-centred monoclinic for (I) and as pseudo-centred triclinic for (II). Both crystal structures are com­prised of one-dimensional chains of alternating trans-Cr(CO)₄(H₂O)₂ and trans-A(CO)₄(H₂O)₂ units μ₂-bridged by bis-chelating oxalate ligands. The resulting linear chains are parallel to the [101] direction for (I) and to the [11] direction for (II). Within the two coordination polymers, strong hydrogen bonds result in tetra­meric R₄⁴(12) synthons which link the metal chains, thus leading to two-dimensaional supra­molecular architectures. The two structures differ from each other with respect to the symmetry relations inside the ligand, the role of electrostatic forces in the crystal structure and the mol­ecular inter­actions of the hydrogen-bonded networks. Moreover, they exhibit the same UV–Vis pattern typical of a Cr^III centrosymmetric geometry, while the IR absorption shows some differences due to the oxalate-ligand conformation. Polymers (I) and (II) are also distinguished by a different behaviours during the decom­position process, the precursor (I) leading to the oxide LiCrO₂, while the residues of (II) consist of a mixture of sodium carbonate and Cr^III oxide.

Computing details

Data collection: COLLECT (Nonius, 1998) for LiCrO; CrysAlis PRO (Agilent, 2014 ) for NaCrO. Cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997) for LiCrO; CrysAlis PRO (Agilent, 2014 ) for NaCrO. Data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997) for LiCrO; CrysAlis PRO (Agilent, 2014 ) for NaCrO. For both structures, program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b). Molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg & Putz, 2008) for LiCrO; ORTEP-3 for Windows (Farrugia, 2012) for NaCrO. For both structures, software used to prepare material for publication: WinGX (Farrugia, 2012).

\ catena-Poly[[diaqualithium(I)]-µ-oxalato-\ κ⁴O¹,O²:O^1',O^2'-[diaquachromium(III)]-\ µ-oxalato-κ⁴O¹,O²:O^1',O^2'] (LiCrO)

Crystal data

[LiCr(C2O4)2(H2O)4]	F(000) = 310
Mr = 307.04	Dx = 1.987 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
a = 10.097 (8) Å	Cell parameters from 2374 reflections
b = 7.787 (8) Å	θ = 3.0–30.0°
c = 6.737 (6) Å	µ = 1.18 mm^−1
β = 104.3 (1)°	T = 100 K
V = 513.3 (8) Å^3	Prism, pink
Z = 2	0.1 × 0.1 × 0.1 mm

Data collection

Bruker KappaCCD diffractometer	776 reflections with I > 2σ(I)
Detector resolution: 9 pixels mm^-1	Rint = 0.048
CCD scans	θmax = 30.4°, θmin = 3.1°
Absorption correction: analytical (Alcock, 1970)	h = −14→14
Tmin = 0.876, Tmax = 0.956	k = −10→10
6772 measured reflections	l = −9→9
809 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.034	Hydrogen site location: difference Fourier map
wR(F^2) = 0.086	H atoms treated by a mixture of independent and constrained refinement
S = 1.14	w = 1/[σ^2(Fo^2) + (0.0476P)^2 + 0.6456P] where P = (Fo^2 + 2Fc^2)/3
809 reflections	(Δ/σ)max = 0.008
61 parameters	Δρmax = 0.90 e Å^−3
5 restraints	Δρmin = −0.47 e Å^−3

Special details

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. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

PLAT112_ALERT_2_C ADDSYM Detects New (Pseudo) Symm. Elem B 83 %Fit Author response:Since the Cr atom is located on an inversion centre, this imposes the occupation of the equivalent inversion centres, which consequently leads to the formation of pseudo-cells B and A respectively, without, however, changing the space group that remains C2/m. PLAT303_ALERT_2_C Full Occupancy Atom H1 with # Connections 2.00 Check Author response: The hydrogen atom H1 is bounded to the each component of the split water oxygen Ow1 (H1-Ow1A and H1-Ow1B).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cr1	0.5000	0.0000	0.5000	0.01135 (16)
Li1	0.0000	0.0000	0.0000	0.0144 (10)
C1	0.24694 (14)	0.1007 (2)	0.2643 (2)	0.0139 (3)
O1	0.14572 (11)	0.17906 (14)	0.16642 (19)	0.0184 (3)
O2	0.35762 (10)	0.16915 (14)	0.37424 (17)	0.0141 (2)
OW2	0.56555 (17)	0.0000	0.2431 (3)	0.0162 (3)
H2	0.6012 (19)	−0.0898 (11)	0.213 (3)	0.024*
OW1A	0.1201 (14)	0.0000	−0.2116 (10)	0.0183 (17)	0.64 (6)
OW1B	0.070 (5)	0.0000	−0.263 (7)	0.038 (7)	0.36 (6)
H1	0.113 (3)	0.0882 (12)	−0.289 (3)	0.057*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr1	0.0086 (2)	0.0068 (2)	0.0177 (3)	0.000	0.00137 (16)	0.000
Li1	0.014 (2)	0.006 (2)	0.021 (3)	0.000	−0.0003 (19)	0.000
C1	0.0124 (6)	0.0095 (7)	0.0194 (7)	−0.0004 (5)	0.0028 (5)	−0.0003 (5)
O1	0.0152 (5)	0.0091 (5)	0.0274 (6)	0.0018 (4)	−0.0016 (4)	−0.0001 (4)
O2	0.0115 (5)	0.0078 (5)	0.0214 (5)	0.0001 (3)	0.0009 (4)	0.0002 (4)
OW2	0.0185 (7)	0.0088 (7)	0.0231 (8)	0.000	0.0082 (6)	0.000
OW1A	0.022 (4)	0.0103 (14)	0.024 (2)	0.000	0.0074 (19)	0.000
OW1B	0.053 (14)	0.012 (3)	0.062 (12)	0.000	0.038 (12)	0.000

Geometric parameters (Å, º)

Cr1—O2	1.9794 (19)	Li1—O1^iv	2.133 (2)
Cr1—O2^i	1.9794 (19)	Li1—O1^v	2.133 (2)
Cr1—O2^ii	1.9794 (19)	Li1—O1^i	2.133 (2)
Cr1—O2^iii	1.9794 (19)	Li1—O1	2.133 (2)
Cr1—OW2^iii	2.000 (2)	C1—O1	1.232 (2)
Cr1—OW2	2.000 (2)	C1—O2	1.293 (2)
Li1—OW1B	2.065 (18)	C1—C1^i	1.568 (4)
Li1—OW1B^iv	2.065 (18)	OW2—H2	0.835 (8)
Li1—OW1A	2.087 (9)	OW1A—H1	0.856 (9)
Li1—OW1A^iv	2.087 (9)	OW1B—H1	0.855 (10)
O2—Cr1—O2^i	83.43 (11)	OW1B—Li1—O1^i	96.4 (12)
O2—Cr1—O2^ii	96.57 (11)	OW1B^iv—Li1—O1^i	83.6 (12)
O2^i—Cr1—O2^ii	180.0	OW1A—Li1—O1^i	85.3 (3)
O2—Cr1—O2^iii	180.0	OW1A^iv—Li1—O1^i	94.7 (3)
O2^i—Cr1—O2^iii	96.57 (11)	O1^iv—Li1—O1^i	98.37 (11)
O2^ii—Cr1—O2^iii	83.43 (11)	O1^v—Li1—O1^i	180.00 (10)
O2—Cr1—OW2^iii	90.56 (8)	OW1B—Li1—O1	96.4 (12)
O2^i—Cr1—OW2^iii	90.56 (8)	OW1B^iv—Li1—O1	83.6 (12)
O2^ii—Cr1—OW2^iii	89.44 (8)	OW1A—Li1—O1	85.3 (3)
O2^iii—Cr1—OW2^iii	89.44 (8)	OW1A^iv—Li1—O1	94.7 (3)
O2—Cr1—OW2	89.44 (8)	O1^iv—Li1—O1	180.0
O2^i—Cr1—OW2	89.44 (8)	O1^v—Li1—O1	98.37 (11)
O2^ii—Cr1—OW2	90.56 (8)	O1^i—Li1—O1	81.63 (11)
O2^iii—Cr1—OW2	90.56 (8)	O1—C1—O2	125.98 (16)
OW2^iii—Cr1—OW2	180.0	O1—C1—C1^i	119.67 (9)
OW1B—Li1—OW1B^iv	180.0	O2—C1—C1^i	114.34 (9)
OW1A—Li1—OW1A^iv	180.0 (5)	C1—O1—Li1	109.32 (13)
OW1B—Li1—O1^iv	83.6 (12)	C1—O2—Cr1	113.85 (12)
OW1B^iv—Li1—O1^iv	96.4 (12)	Cr1—OW2—H2	117.9 (13)
OW1A—Li1—O1^iv	94.7 (3)	Li1—OW1A—H1	116.5 (14)
OW1A^iv—Li1—O1^iv	85.3 (3)	Li1—OW1B—H1	119 (3)
OW1B—Li1—O1^v	83.6 (12)	H1—OW1A—H1^i	107.0 (9)
OW1B^iv—Li1—O1^v	96.4 (12)	H1—OW1B—H1^i	107.2 (9)
OW1A—Li1—O1^v	94.7 (3)	H2—OW2—H2^i	113.9 (8)
OW1A^iv—Li1—O1^v	85.3 (3)	H1—OW1—H1^i	107.26 (9)
O1^iv—Li1—O1^v	81.63 (11)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
OW2—H2···O1^vi	0.84 (1)	1.90 (1)	2.716 (3)	165 (2)
OW1A—H1···O2^vii	0.86 (1)	2.02 (1)	2.830 (4)	159 (2)
OW1B—H1···O2^vii	0.86 (1)	2.02 (1)	2.828 (5)	158 (2)

Symmetry codes: (vi) x+1/2, y−1/2, z; (vii) −x+1/2, −y+1/2, −z.

\ catena-Poly[[diaquasodium(I)]-µ-oxalato-\ κ⁴O¹,O²:O^1',O^2'-[diaquachromium(III)]-\ µ-oxalato-κ⁴O¹,O²:O^1',O^2'] (NaCrO)

Crystal data

[NaCr(C2O4)2(H2O)4]	Z = 1
Mr = 323.09	F(000) = 163
Triclinic, P1	Dx = 2.060 Mg m^−3
a = 5.3036 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.5842 (3) Å	Cell parameters from 3252 reflections
c = 8.1882 (4) Å	θ = 3.9–31.9°
α = 96.630 (4)°	µ = 1.21 mm^−1
β = 92.666 (4)°	T = 297 K
γ = 112.865 (5)°	Prismatic, purple
V = 260.39 (2) Å^3	0.25 × 0.20 × 0.15 mm

Data collection

Agilent Xcalibur Sapphire2 (large Be window) diffractometer	1736 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1598 reflections with I > 2σ(I)
Detector resolution: 8.3622 pixels mm^-1	Rint = 0.042
ω scans	θmax = 32.7°, θmin = 3.9°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −7→7
Tmin = 0.817, Tmax = 1.000	k = −9→9
4899 measured reflections	l = −11→12

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	Hydrogen site location: difference Fourier map
wR(F^2) = 0.082	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0415P)^2 + 0.0519P] where P = (Fo^2 + 2Fc^2)/3
1736 reflections	(Δ/σ)max < 0.001
97 parameters	Δρmax = 0.46 e Å^−3
6 restraints	Δρmin = −0.51 e Å^−3

Special details

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. Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

PLAT110_ALERT_2_B ADDSYM Detects Potential Lattice Translation ··· ? Check Author response:No additional translation symmetry, we think it is due to the position of Cr atom in the centre of the unit cell (the same crystallographic site that Li) which position is a possible origin by lattice translation. PLATON ADSSYM indicated that P-1 is the correct space group. PLAT112_ALERT_2_B ADDSYM Detects New (Pseudo) Symm. Elem I 100 %Fit Author response: No additional symmetry, it is due to the position of Cr atom in the centre of the unit cell, for the same reason. PLATON ADSSYM indicated that P(-1) is the correct group. PLAT113_ALERT_2_B ADDSYM Suggests Possible Pseudo/New Space Group P-1 Check Author response:No additional symmetry, it may be due to the position of chromium atom in the centre of the unit cell. PLATON ADSSYM indicated that P(-1) is the correct group.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cr	0.5000	0.5000	0.5000	0.02061 (10)
Na	1.0000	1.0000	0.0000	0.02969 (19)
O1	0.86629 (19)	0.69304 (16)	0.44984 (12)	0.0248 (2)
O2	1.0752 (2)	0.89534 (17)	0.25704 (13)	0.0280 (2)
O3	0.38970 (19)	0.54995 (17)	0.27943 (12)	0.0261 (2)
O4	0.5663 (2)	0.74374 (18)	0.07621 (13)	0.0304 (2)
C1	0.8714 (2)	0.7679 (2)	0.31276 (16)	0.0208 (2)
C2	0.5865 (3)	0.6834 (2)	0.20967 (16)	0.0217 (2)
OW1	1.1380 (2)	0.72011 (18)	−0.14304 (14)	0.0313 (2)
H1	1.232 (4)	0.692 (3)	−0.070 (2)	0.047*
H2	0.985 (3)	0.609 (3)	−0.166 (3)	0.047*
OW2	0.5430 (2)	0.22538 (17)	0.40057 (14)	0.0290 (2)
H3	0.394 (3)	0.115 (3)	0.364 (2)	0.043*
H4	0.659 (3)	0.245 (3)	0.332 (2)	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr	0.01482 (14)	0.02512 (16)	0.01773 (16)	0.00227 (10)	0.00120 (10)	0.00754 (11)
Na	0.0323 (4)	0.0325 (4)	0.0252 (4)	0.0111 (3)	0.0088 (3)	0.0121 (3)
O1	0.0169 (4)	0.0321 (5)	0.0213 (5)	0.0036 (3)	0.0012 (3)	0.0099 (4)
O2	0.0193 (4)	0.0318 (5)	0.0263 (5)	0.0012 (4)	0.0034 (4)	0.0103 (4)
O3	0.0170 (4)	0.0338 (5)	0.0219 (5)	0.0025 (4)	−0.0004 (3)	0.0103 (4)
O4	0.0257 (5)	0.0369 (5)	0.0241 (5)	0.0056 (4)	−0.0009 (4)	0.0135 (4)
C1	0.0173 (5)	0.0224 (5)	0.0204 (6)	0.0053 (4)	0.0015 (4)	0.0041 (4)
C2	0.0192 (5)	0.0227 (5)	0.0201 (6)	0.0048 (4)	0.0004 (4)	0.0042 (4)
OW1	0.0236 (5)	0.0360 (5)	0.0297 (6)	0.0076 (4)	−0.0013 (4)	0.0037 (4)
OW2	0.0209 (5)	0.0286 (5)	0.0322 (6)	0.0044 (4)	0.0032 (4)	0.0037 (4)

Geometric parameters (Å, º)

Cr—O1	1.9581 (9)	Na—C1^ii	3.1007 (13)
Cr—O1^i	1.9581 (9)	Na—C2^ii	3.1187 (13)
Cr—O3	1.9751 (10)	Na—C2	3.1187 (13)
Cr—O3^i	1.9751 (10)	O1—C1	1.2744 (16)
Cr—OW2^i	1.9956 (10)	O2—C1	1.2286 (15)
Cr—OW2	1.9956 (10)	O3—C2	1.2832 (16)
Na—O2^ii	2.3525 (11)	O4—C2	1.2191 (17)
Na—O2	2.3525 (11)	C1—C2	1.5571 (19)
Na—O4	2.4263 (10)	OW1—H1	0.840 (9)
Na—O4^ii	2.4263 (10)	OW1—H2	0.848 (9)
Na—OW1^ii	2.4357 (11)	OW2—H3	0.848 (9)
Na—OW1	2.4357 (11)	OW2—H4	0.831 (9)
Na—C1	3.1007 (13)
O1—Cr—O1^i	180.0	OW1—Na—C1^ii	86.03 (4)
O1—Cr—O3	82.62 (4)	C1—Na—C1^ii	180.0
O1^i—Cr—O3	97.38 (4)	O2^ii—Na—C2^ii	49.78 (3)
O1—Cr—O3^i	97.38 (4)	O2—Na—C2^ii	130.22 (3)
O1^i—Cr—O3^i	82.62 (4)	O4—Na—C2^ii	158.98 (4)
O3—Cr—O3^i	180.0	O4^ii—Na—C2^ii	21.02 (4)
O1—Cr—OW2^i	87.71 (4)	OW1^ii—Na—C2^ii	96.39 (4)
O1^i—Cr—OW2^i	92.30 (4)	OW1—Na—C2^ii	83.61 (4)
O3—Cr—OW2^i	89.31 (5)	C1—Na—C2^ii	151.00 (4)
O3^i—Cr—OW2^i	90.69 (5)	C1^ii—Na—C2^ii	29.00 (4)
O1—Cr—OW2	92.30 (4)	O2^ii—Na—C2	130.22 (3)
O1^i—Cr—OW2	87.70 (4)	O2—Na—C2	49.78 (3)
O3—Cr—OW2	90.69 (5)	O4—Na—C2	21.02 (4)
O3^i—Cr—OW2	89.31 (5)	O4^ii—Na—C2	158.98 (4)
OW2^i—Cr—OW2	180.0	OW1^ii—Na—C2	83.61 (4)
O2^ii—Na—O2	180.0	OW1—Na—C2	96.39 (4)
O2^ii—Na—O4	109.21 (3)	C1—Na—C2	29.00 (4)
O2—Na—O4	70.80 (3)	C1^ii—Na—C2	151.00 (4)
O2^ii—Na—O4^ii	70.79 (3)	C2^ii—Na—C2	180.0
O2—Na—O4^ii	109.21 (3)	C1—O1—Cr	114.76 (8)
O4—Na—O4^ii	180.0	C1—O2—Na	116.40 (9)
O2^ii—Na—OW1^ii	91.17 (4)	C2—O3—Cr	114.55 (8)
O2—Na—OW1^ii	88.83 (4)	C2—O4—Na	113.44 (9)
O4—Na—OW1^ii	83.06 (4)	O2—C1—O1	126.48 (12)
O4^ii—Na—OW1^ii	96.94 (4)	O2—C1—C2	118.94 (12)
O2^ii—Na—OW1	88.83 (4)	O1—C1—C2	114.57 (10)
O2—Na—OW1	91.17 (4)	O2—C1—Na	42.81 (7)
O4—Na—OW1	96.94 (4)	O1—C1—Na	169.28 (9)
O4^ii—Na—OW1	83.06 (4)	C2—C1—Na	76.14 (7)
OW1^ii—Na—OW1	180.0	O4—C2—O3	126.21 (12)
O2^ii—Na—C1	159.21 (3)	O4—C2—C1	120.40 (12)
O2—Na—C1	20.79 (3)	O3—C2—C1	113.38 (11)
O4—Na—C1	50.01 (3)	O4—C2—Na	45.55 (7)
O4^ii—Na—C1	129.99 (3)	O3—C2—Na	171.75 (9)
OW1^ii—Na—C1	86.03 (4)	C1—C2—Na	74.86 (7)
OW1—Na—C1	93.97 (4)	Na—OW1—H1	104.8 (16)
O2^ii—Na—C1^ii	20.79 (3)	Na—OW1—H2	101.9 (15)
O2—Na—C1^ii	159.21 (3)	H1—OW1—H2	108.7 (17)
O4—Na—C1^ii	129.99 (3)	Cr—OW2—H3	115.4 (14)
O4^ii—Na—C1^ii	50.01 (3)	Cr—OW2—H4	115.1 (14)
OW1^ii—Na—C1^ii	93.97 (4)	H3—OW2—H4	110.9 (17)
Na—O2—C1—O1	−179.22 (10)	O2—C1—C2—O4	−0.4 (2)
Na—O2—C1—C2	1.27 (15)	O1—C1—C2—O4	−179.91 (12)
Cr—O1—C1—O2	178.24 (11)	Na—C1—C2—O4	0.54 (12)
Cr—O1—C1—C2	−2.24 (14)	O2—C1—C2—O3	179.41 (11)
Cr—O1—C1—Na	175.4 (4)	O1—C1—C2—O3	−0.16 (17)
Na—O4—C2—O3	179.55 (11)	Na—C1—C2—O3	−179.70 (11)
Na—O4—C2—C1	−0.73 (16)	O2—C1—C2—Na	−0.89 (11)
Cr—O3—C2—O4	−177.81 (12)	O1—C1—C2—Na	179.55 (11)
Cr—O3—C2—C1	2.45 (14)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
OW1—H1···O4^iii	0.84 (1)	1.99 (1)	2.7731 (16)	156 (2)
OW1—H2···O3^iv	0.85 (1)	1.97 (1)	2.7612 (14)	154 (2)
OW2—H3···O2^v	0.85 (1)	1.84 (1)	2.6849 (14)	172 (2)
OW2—H4···OW1^vi	0.83 (1)	1.91 (1)	2.7336 (16)	168 (2)

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