Redetermination of MgCrO4·5H2O.

The CCD-data based redetermination of the crystal structure of the title compound, magnesium chromate(VI) penta-hydrate, confirms in principle the previous study based on precession film data [Bertrand et al. (1971 ▶). C. R. Hebd. Seances Acad. Sci. Serie C, 272, 530-533.], but with all atoms refined with anisotropic displacement parameters and with all H atoms localized. This allowed an unambiguous assignment of the hydrogen-bonding pattern. MgCrO4·5H2O adopts the MgSO4·5H2O structure type. It contains two Mg(2+) sites on special positions with site symmetry -1, one tetra-hedral CrO4 group and five water mol-ecules. Four of them coordinate to the Mg(2+) cation, and one is an uncoordinating lattice water mol-ecule. The octa-hedral environment of the Mg(2+) cation is completed by two axial O atoms of CrO4 tetra-hedra. This arrangement leads to the formation of chains parallel to [011]. Adjacent chains are linked through O-H⋯O hydrogen bonds (one of them bifurcated), involving both the coordi-nating and lattice water mol-ecules, into a three-dimensional network.

Related literature

For the original structure determination of the title compound, see: Bertrand et al. (1971 ▶). For hydrogen-bonding pattern in the structures of MXO4·5H2O compounds (M = Mg, Cu; X = S, Cr), see: Baur & Rolin (1972 ▶). For Cr—O bond length distributions in chromates(VI), see: Pressprich et al. (1988 ▶). For bond lengths and angles in the related structure of MgCrO4·11H2O, see: Fortes et al. (2013 ▶). For standardization of structure data, see: Gelato & Parthé (1987 ▶).

Experimental

Crystal data

MgCrO4·5H2O

M = 230.39

Triclinic,

a = 6.1467 (3) Å

b = 6.3742 (4) Å

c = 10.7048 (6) Å

α = 75.919 (4)°

β = 81.603 (3)°

γ = 71.134 (3)°

V = 383.92 (4) Å3

Z = 2

Mo Kα radiation

μ = 1.59 mm−1

T = 296 K

0.10 × 0.08 × 0.01 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2011 ▶) T min = 0.594, T max = 0.748

10569 measured reflections

4019 independent reflections

3340 reflections with I > 2σ(I)

R int = 0.031

Refinement

R[F 2 > 2σ(F 2)] = 0.031

wR(F 2) = 0.069

S = 1.02

4019 reflections

143 parameters

10 restraints

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 1.17 e Å−3

Δρmin = −0.72 e Å−3

Data collection: APEX2 (Bruker, 2011 ▶); cell refinement: SAINT (Bruker, 2011 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ATOMS for Windows (Dowty, 2008 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813018588/br2229sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813018588/br2229Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

MgCrO4·5H2O	Z = 2
Mr = 230.39	F(000) = 236
Triclinic, P1	Dx = 1.993 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.1467 (3) Å	Cell parameters from 3623 reflections
b = 6.3742 (4) Å	θ = 3.5–39.7°
c = 10.7048 (6) Å	µ = 1.59 mm−1
α = 75.919 (4)°	T = 296 K
β = 81.603 (3)°	Plate, yellow
γ = 71.134 (3)°	0.10 × 0.08 × 0.01 mm
V = 383.92 (4) Å3

Bruker APEXII CCD diffractometer	4019 independent reflections
Radiation source: fine-focus sealed tube	3340 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ω– and φ–scans	θmax = 37.5°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Bruker, 2011)	h = −10→10
Tmin = 0.594, Tmax = 0.748	k = −10→10
10569 measured reflections	l = −17→18

Refinement on F2	Primary atom site location: isomorphous structure methods
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.069	w = 1/[σ2(Fo2) + (0.0263P)2 + 0.1663P] where P = (Fo2 + 2Fc2)/3
S = 1.02	(Δ/σ)max < 0.001
4019 reflections	Δρmax = 1.17 e Å−3
143 parameters	Δρmin = −0.72 e Å−3
10 restraints

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.

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 > σ(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.

	x	y	z	Uiso*/Ueq
Mg1	0.0000	0.0000	0.0000	0.00672 (11)
Mg2	0.0000	0.5000	0.5000	0.00587 (10)
Cr1	0.35414 (3)	0.02843 (3)	0.709355 (18)	0.00508 (4)
O1	0.17472 (14)	0.28496 (15)	0.66131 (9)	0.00919 (15)
O2	0.61762 (13)	0.04795 (15)	0.70554 (9)	0.00825 (15)
O3	0.64389 (14)	0.14163 (16)	0.38351 (9)	0.00978 (16)
O4	0.72867 (14)	0.07678 (16)	0.14081 (9)	0.00919 (15)
OW1	0.30276 (14)	0.54057 (17)	0.40541 (10)	0.01038 (16)
HW1A	0.331 (4)	0.660 (3)	0.378 (2)	0.029 (6)*
HW1B	0.413 (3)	0.435 (3)	0.397 (2)	0.032 (6)*
OW2	0.16925 (14)	0.70426 (17)	0.12175 (9)	0.01025 (16)
HW2A	0.118 (4)	0.675 (4)	0.1938 (16)	0.027 (6)*
HW2B	0.305 (3)	0.669 (4)	0.130 (2)	0.026 (5)*
OW3	0.16025 (16)	0.18082 (17)	0.06898 (10)	0.01161 (17)
HW3A	0.240 (3)	0.115 (3)	0.1307 (17)	0.024 (5)*
HW3B	0.221 (4)	0.263 (4)	0.016 (2)	0.038 (7)*
OW4	0.65171 (16)	0.54576 (17)	0.13300 (10)	0.01237 (17)
HW4A	0.689 (4)	0.414 (3)	0.130 (2)	0.036 (7)*
HW4B	0.714 (4)	0.560 (4)	0.1924 (18)	0.030 (6)*
OW5	0.03331 (14)	0.23596 (17)	0.41734 (10)	0.01081 (16)
HW5A	−0.076 (3)	0.201 (4)	0.413 (2)	0.023 (5)*
HW5B	0.143 (3)	0.156 (3)	0.384 (2)	0.029 (6)*

	U11	U22	U33	U12	U13	U23
Mg1	0.0071 (2)	0.0069 (3)	0.0059 (3)	−0.00218 (18)	−0.00012 (17)	−0.0010 (2)
Mg2	0.0065 (2)	0.0051 (3)	0.0058 (3)	−0.00195 (18)	−0.00013 (17)	−0.0007 (2)
Cr1	0.00505 (6)	0.00478 (8)	0.00506 (8)	−0.00132 (5)	−0.00015 (5)	−0.00072 (6)
O1	0.0101 (3)	0.0067 (4)	0.0085 (4)	−0.0003 (3)	−0.0012 (3)	−0.0001 (3)
O2	0.0072 (3)	0.0092 (4)	0.0093 (4)	−0.0038 (3)	−0.0002 (3)	−0.0021 (3)
O3	0.0102 (3)	0.0092 (4)	0.0113 (4)	−0.0021 (3)	−0.0015 (3)	−0.0054 (3)
O4	0.0100 (3)	0.0084 (4)	0.0071 (4)	−0.0023 (3)	0.0017 (3)	0.0004 (3)
OW1	0.0078 (3)	0.0071 (4)	0.0147 (4)	−0.0024 (3)	0.0022 (3)	−0.0010 (3)
OW2	0.0094 (3)	0.0116 (4)	0.0074 (4)	−0.0020 (3)	−0.0003 (3)	0.0006 (3)
OW3	0.0143 (4)	0.0125 (4)	0.0099 (4)	−0.0075 (3)	−0.0038 (3)	0.0007 (3)
OW4	0.0140 (4)	0.0081 (4)	0.0141 (5)	−0.0029 (3)	0.0001 (3)	−0.0018 (3)
OW5	0.0078 (3)	0.0105 (4)	0.0162 (5)	−0.0024 (3)	0.0002 (3)	−0.0075 (3)

Mg1—OW3i	2.0505 (9)	Mg2—OW1	2.0467 (8)
Mg1—OW3	2.0505 (9)	Mg2—OW1vi	2.0467 (8)
Mg1—OW2ii	2.0656 (9)	Mg2—O1	2.1099 (9)
Mg1—OW2iii	2.0656 (9)	Mg2—O1vi	2.1099 (9)
Mg1—O4iv	2.0952 (9)	Cr1—O3vii	1.6357 (9)
Mg1—O4v	2.0952 (9)	Cr1—O4vii	1.6554 (9)
Mg2—OW5	2.0265 (10)	Cr1—O1	1.6568 (9)
Mg2—OW5vi	2.0265 (10)	Cr1—O2	1.6579 (8)
OW3i—Mg1—OW3	180.00 (5)	OW5vi—Mg2—O1vi	92.35 (4)
OW3i—Mg1—OW2ii	90.97 (4)	OW1—Mg2—O1vi	88.90 (4)
OW3—Mg1—OW2ii	89.03 (4)	OW1vi—Mg2—O1vi	91.10 (4)
OW3i—Mg1—OW2iii	89.03 (4)	O1—Mg2—O1vi	180.00 (3)
OW3—Mg1—OW2iii	90.97 (4)	O3vii—Cr1—O4vii	109.01 (5)
OW2ii—Mg1—OW2iii	180.00 (7)	O3vii—Cr1—O1	111.25 (5)
OW3i—Mg1—O4iv	91.55 (4)	O4vii—Cr1—O1	108.90 (5)
OW3—Mg1—O4iv	88.45 (4)	O3vii—Cr1—O2	109.30 (4)
OW2ii—Mg1—O4iv	88.19 (4)	O4vii—Cr1—O2	109.31 (4)
OW2iii—Mg1—O4iv	91.81 (4)	O1—Cr1—O2	109.05 (4)
OW3i—Mg1—O4v	88.45 (4)	Cr1—O1—Mg2	142.08 (6)
OW3—Mg1—O4v	91.55 (4)	Cr1vii—O4—Mg1viii	140.12 (5)
OW2ii—Mg1—O4v	91.81 (4)	Mg2—OW1—HW1A	126.4 (16)
OW2iii—Mg1—O4v	88.19 (4)	Mg2—OW1—HW1B	121.9 (17)
O4iv—Mg1—O4v	180.00 (5)	HW1A—OW1—HW1B	111 (2)
OW5—Mg2—OW5vi	180.00 (5)	Mg1ix—OW2—HW2A	119.3 (16)
OW5—Mg2—OW1	90.91 (4)	Mg1ix—OW2—HW2B	122.2 (15)
OW5vi—Mg2—OW1	89.09 (4)	HW2A—OW2—HW2B	102 (2)
OW5—Mg2—OW1vi	89.09 (4)	Mg1—OW3—HW3A	118.2 (15)
OW5vi—Mg2—OW1vi	90.91 (4)	Mg1—OW3—HW3B	117.0 (18)
OW1—Mg2—OW1vi	180.0	HW3A—OW3—HW3B	111 (2)
OW5—Mg2—O1	92.35 (4)	HW4A—OW4—HW4B	109 (2)
OW5vi—Mg2—O1	87.65 (4)	Mg2—OW5—HW5A	119.5 (16)
OW1—Mg2—O1	91.10 (4)	Mg2—OW5—HW5B	131.6 (16)
OW1vi—Mg2—O1	88.90 (4)	HW5A—OW5—HW5B	109 (2)
OW5—Mg2—O1vi	87.65 (4)

D—H···A	D—H	H···A	D···A	D—H···A
OW1—HW1A···O2x	0.81 (2)	1.96 (2)	2.7702 (13)	174 (2)
OW1—HW1B···O3	0.80 (2)	1.97 (2)	2.7598 (13)	169 (2)
OW2—HW2A···O1vi	0.79 (2)	2.19 (2)	2.9014 (13)	150 (2)
OW2—HW2A···OW1	0.79 (2)	2.52 (2)	3.1008 (14)	132 (2)
OW2—HW2B···OW4	0.80 (2)	2.02 (2)	2.8173 (12)	171 (2)
OW3—HW3A···O2vii	0.82 (2)	1.97 (2)	2.7891 (13)	170 (2)
OW3—HW3B···OW4xi	0.81 (2)	1.99 (2)	2.7906 (14)	172 (2)
OW4—HW4B···O1x	0.83 (2)	2.32 (2)	3.1205 (14)	163 (2)
OW4—HW4A···O4	0.80 (2)	2.06 (2)	2.8535 (14)	170 (2)
OW5—HW5B···O2vii	0.80 (2)	1.93 (2)	2.7262 (13)	173 (2)
OW5—HW5A···O3iv	0.79 (2)	1.96 (2)	2.7409 (12)	174 (2)

Table 1

Selected bond lengths (Å)

Mg1—OW3	2.0505 (9)
Mg1—OW2i	2.0656 (9)
Mg1—O4ii	2.0952 (9)
Mg2—OW5	2.0265 (10)
Mg2—OW1	2.0467 (8)
Mg2—O1	2.1099 (9)
Cr1—O3iii	1.6357 (9)
Cr1—O4iii	1.6554 (9)
Cr1—O1	1.6568 (9)
Cr1—O2	1.6579 (8)

Symmetry codes: (i) ; (ii) ; (iii) .

Table 2

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
OW1—HW1A⋯O2iv	0.81 (2)	1.96 (2)	2.7702 (13)	174 (2)
OW1—HW1B⋯O3	0.80 (2)	1.97 (2)	2.7598 (13)	169 (2)
OW2—HW2A⋯O1v	0.79 (2)	2.19 (2)	2.9014 (13)	150 (2)
OW2—HW2A⋯OW1	0.79 (2)	2.52 (2)	3.1008 (14)	132 (2)
OW2—HW2B⋯OW4	0.80 (2)	2.02 (2)	2.8173 (12)	171 (2)
OW3—HW3A⋯O2iii	0.82 (2)	1.97 (2)	2.7891 (13)	170 (2)
OW3—HW3B⋯OW4vi	0.81 (2)	1.99 (2)	2.7906 (14)	172 (2)
OW4—HW4B⋯O1iv	0.83 (2)	2.32 (2)	3.1205 (14)	163 (2)
OW4—HW4A⋯O4	0.80 (2)	2.06 (2)	2.8535 (14)	170 (2)
OW5—HW5B⋯O2iii	0.80 (2)	1.93 (2)	2.7262 (13)	173 (2)
OW5—HW5A⋯O3vii	0.79 (2)	1.96 (2)	2.7409 (12)	174 (2)

Symmetry codes: (iii) ; (iv) ; (v) ; (vi) ; (vii) .