α-Nickel sulfate hexahydrate crystals: relationship of growth conditions, crystal structure and properties

Studies on α-nickel sulfate hexahydrate (NSH) crystals grown under different conditions are undertaken to investigate how changes in growth conditions affect crystal properties and whether or not there is any modification of the average crystal structure due to changes in crystallization conditions. Thermogravimetric and microhardness studies were carried out on the crystals grown from two different aqueous solutions, one of them containing an excess of sulfuric acid. Raman spectra were recorded and a single-crystal neutron diffraction investigation was conducted on both crystals. A detailed comparison between the two crystal structures and their Raman spectra showed that, although the two crystal structures are very similar, there are slight differences, such as the change in unit-cell volume, differences in the ionic structure, particularly of the sulfate ions, and changes in the hydrogen-bonding network. During solution crystal growth of a salt like NSH, varying the ionic environment around the solute ions influences the interionic interactions between them. Hence it is suggested that the above-mentioned structural differences result from a fine-tuning of the interionic interaction between the cations and anions of NSH in the solution phase. This difference is finally carried over to the crystalline phase. The resulting small crystal structure differences are enough to produce measurable changes in the thermal stability and fragility of the crystals. These differences in crystal properties can be explained on the basis of the observed structural differences between the two crystals grown under different conditions.

Computing details

For both structures, data collection: SCAD; cell refinement: REFINE; data reduction: DATRED; program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2014); molecular graphics: ORTEP; software used to prepare material for publication: SHELX.

(I)

Crystal data

H12NiO6·O4S	Dx = 2.083 Mg m^−3
Mr = 263.09	Neutron radiation, λ = 0.995 Å
Tetragonal, P41212	Cell parameters from 50 reflections
a = 6.775 (2) Å	θ = 4–40°
c = 18.275 (4) Å	µ = 0.23 mm^−1
V = 838.8 (5) Å^3	T = 300 K
Z = 4	Cubic, blue
F(000) = 105	3 × 3 × 3 mm

Data collection

Four circle diffractometer	Rint = 0.000
Radiation source: Dhruva reactor	θmax = 43.3°, θmin = 4.5°
τ–\2t scans	h = 0→9
Absorption correction: integration datred	k = −9→0
	l = 0→25
743 measured reflections	2 standard reflections every 20 reflections
743 independent reflections	intensity decay: <3
467 reflections with I > 2σ(I)

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.1313P)^2 + 27.9835P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.082	(Δ/σ)max < 0.001
wR(F^2) = 0.295	Δρmax = 1.33 e Å^−3
S = 1.18	Δρmin = −1.72 e Å^−3
743 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
111 parameters	Extinction coefficient: 0.13 (2)
0 restraints	Absolute structure: All f" are zero, so absolute structure could not be determined
Hydrogen site location: difference Fourier map

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.

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

	x	y	z	Uiso*/Ueq
Ni	0.2111 (5)	0.2111 (5)	0.0000	0.0119 (11)
O1	0.1716 (12)	−0.0478 (12)	0.0530 (4)	0.0253 (18)
O2	0.4717 (11)	0.2438 (11)	0.0563 (3)	0.0197 (16)
O3	0.0641 (11)	0.3564 (11)	0.0848 (3)	0.0195 (15)
H11	0.080 (2)	−0.142 (2)	0.0405 (8)	0.036 (3)
H12	0.249 (3)	−0.081 (2)	0.0941 (7)	0.038 (3)
H21	0.565 (2)	0.146 (3)	0.0469 (10)	0.044 (3)
H22	0.533 (3)	0.375 (2)	0.0592 (9)	0.039 (3)
H31	−0.013 (2)	0.463 (2)	0.0660 (8)	0.038 (3)
H32	−0.0171 (19)	0.274 (2)	0.1176 (7)	0.029 (3)
S	0.707 (2)	0.707 (2)	0.0000	0.015 (3)
O4	0.6208 (15)	0.6209 (13)	0.0659 (4)	0.0312 (18)
O5	0.9216 (11)	0.6727 (11)	0.0003 (5)	0.0266 (16)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni	0.0131 (13)	0.0131 (13)	0.0096 (16)	−0.0008 (16)	−0.0005 (10)	0.0005 (10)
O1	0.034 (4)	0.020 (3)	0.022 (3)	−0.008 (3)	−0.011 (3)	0.008 (3)
O2	0.015 (3)	0.020 (3)	0.023 (3)	−0.002 (3)	−0.003 (2)	−0.003 (3)
O3	0.023 (3)	0.022 (3)	0.014 (2)	0.003 (3)	−0.002 (2)	−0.003 (3)
H11	0.040 (7)	0.024 (6)	0.043 (6)	−0.006 (6)	−0.005 (6)	−0.001 (5)
H12	0.045 (8)	0.039 (8)	0.032 (6)	0.000 (6)	−0.010 (6)	0.012 (5)
H21	0.022 (6)	0.047 (8)	0.061 (9)	0.005 (7)	−0.003 (6)	0.002 (8)
H22	0.045 (8)	0.026 (6)	0.045 (7)	−0.006 (6)	0.000 (6)	−0.005 (6)
H31	0.042 (8)	0.031 (7)	0.041 (6)	0.014 (6)	0.002 (6)	0.002 (6)
H32	0.025 (5)	0.034 (7)	0.028 (5)	0.002 (5)	0.002 (4)	−0.005 (5)
S	0.013 (4)	0.013 (4)	0.018 (6)	0.001 (6)	0.002 (4)	−0.002 (4)
O4	0.047 (5)	0.025 (4)	0.021 (3)	−0.010 (3)	0.006 (3)	0.002 (3)
O5	0.019 (3)	0.020 (3)	0.041 (4)	0.005 (2)	−0.007 (3)	−0.004 (3)

Geometric parameters (Å, º)

Ni—O1	2.021 (8)	O2—H21	0.93 (2)
Ni—O1^i	2.021 (8)	O2—H22	0.981 (16)
Ni—O2	2.055 (7)	O3—H31	0.955 (15)
Ni—O2^i	2.055 (7)	O3—H32	0.988 (16)
Ni—O3^i	2.088 (6)	S—O4	1.460 (12)
Ni—O3	2.088 (6)	S—O4^i	1.460 (12)
O1—H11	0.917 (17)	S—O5^i	1.473 (13)
O1—H12	0.944 (14)	S—O5	1.473 (13)
O1—Ni—O1^i	90.0 (5)	Ni—O1—H11	124.9 (11)
O1—Ni—O2	88.1 (3)	Ni—O1—H12	121.0 (12)
O1^i—Ni—O2	178.1 (4)	H11—O1—H12	114.1 (15)
O1—Ni—O2^i	178.1 (4)	Ni—O2—H21	114.4 (11)
O1^i—Ni—O2^i	88.1 (3)	Ni—O2—H22	119.3 (12)
O2—Ni—O2^i	93.8 (4)	H21—O2—H22	111.6 (16)
O1—Ni—O3^i	90.2 (3)	Ni—O3—H31	110.6 (10)
O1^i—Ni—O3^i	89.4 (3)	Ni—O3—H32	116.6 (9)
O2—Ni—O3^i	91.0 (3)	H31—O3—H32	110.1 (14)
O2^i—Ni—O3^i	89.3 (3)	O4—S—O4^i	111.2 (14)
O1—Ni—O3	89.4 (3)	O4—S—O5^i	109.5 (5)
O1^i—Ni—O3	90.3 (3)	O4^i—S—O5^i	109.2 (5)
O2—Ni—O3	89.3 (3)	O4—S—O5	109.2 (5)
O2^i—Ni—O3	91.0 (3)	O4^i—S—O5	109.5 (5)
O3^i—Ni—O3	179.6 (5)	O5^i—S—O5	108.1 (13)

Symmetry code: (i) y, x, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···O5^ii	0.917 (17)	1.810 (16)	2.717 (11)	169.8 (16)
O1—H11···S^ii	0.917 (17)	2.83 (2)	3.690 (19)	157.1 (13)
O1—H12···O3^iii	0.944 (14)	1.862 (15)	2.799 (10)	171.1 (17)
O2—H21···O5^iv	0.93 (2)	1.892 (19)	2.773 (11)	156.5 (15)
O2—H22···O4	0.981 (16)	1.775 (17)	2.753 (11)	174.4 (18)
O2—H22···S	0.981 (16)	2.76 (2)	3.666 (19)	153.7 (12)
O3—H31···O5^v	0.955 (15)	1.912 (16)	2.812 (10)	156.1 (14)
O3—H31···S^v	0.955 (15)	2.791 (15)	3.728 (7)	167.0 (15)
O3—H32···O4^iii	0.988 (16)	1.744 (16)	2.722 (12)	169.6 (13)
O3—H32···S^iii	0.988 (16)	2.777 (13)	3.676 (8)	151.5 (10)

Symmetry codes: (ii) x−1, y−1, z; (iii) −x+1/2, y−1/2, −z+1/4; (iv) y, x−1, −z; (v) x−1, y, z.

(II)

Crystal data

H12NiO6·O4S	Dx = 2.077 Mg m^−3
Mr = 263.09	Neutron radiation, λ = 0.995 Å
Tetragonal, P41212	Cell parameters from 50 reflections
a = 6.785 (2) Å	θ = 4–40°
c = 18.279 (5) Å	µ = 0.23 mm^−1
V = 841.5 (5) Å^3	T = 300 K
Z = 4	Cubic, blue
F(000) = 105	3 × 3 × 3 mm

Data collection

Four circle diffractometer	Rint = 0.007
Radiation source: Dhruva reactor	θmax = 43.3°, θmin = 4.5°
τ–\2t scans	h = 0→9
Absorption correction: integration datred	k = −8→0
	l = 0→25
745 measured reflections	2 standard reflections every 20 reflections
744 independent reflections	intensity decay: <3
471 reflections with I > 2σ(I)

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.1174P)^2 + 4.1936P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.070	(Δ/σ)max < 0.001
wR(F^2) = 0.245	Δρmax = 1.22 e Å^−3
S = 1.25	Δρmin = −1.30 e Å^−3
744 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
111 parameters	Extinction coefficient: 0.19 (3)
0 restraints	Absolute structure: All f" are zero, so absolute structure could not be determined
Hydrogen site location: difference Fourier map

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.

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

	x	y	z	Uiso*/Ueq
Ni	0.2103 (4)	0.2103 (4)	0.0000	0.0137 (9)
O1	0.1734 (11)	−0.0480 (11)	0.0529 (3)	0.0276 (15)
O2	0.4722 (9)	0.2447 (9)	0.0561 (3)	0.0197 (13)
O3	0.0650 (9)	0.3556 (9)	0.0849 (3)	0.0197 (13)
H11	0.0799 (19)	−0.1428 (18)	0.0412 (8)	0.038 (3)
H12	0.248 (2)	−0.081 (2)	0.0953 (6)	0.042 (3)
H21	0.5681 (19)	0.145 (2)	0.0476 (8)	0.041 (3)
H22	0.535 (2)	0.3732 (18)	0.0593 (7)	0.035 (3)
H31	−0.0139 (19)	0.4650 (18)	0.0659 (7)	0.038 (3)
H32	−0.0139 (19)	0.2711 (18)	0.1168 (6)	0.032 (2)
S	0.7083 (17)	0.7083 (17)	0.0000	0.016 (2)
O4	0.6208 (13)	0.6204 (11)	0.0659 (3)	0.0309 (15)
O5	0.9227 (9)	0.6731 (10)	0.0005 (4)	0.0268 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni	0.0139 (12)	0.0139 (12)	0.0134 (15)	−0.0014 (14)	−0.0009 (9)	0.0009 (9)
O1	0.033 (3)	0.027 (3)	0.023 (3)	−0.007 (3)	−0.008 (3)	0.006 (2)
O2	0.018 (3)	0.018 (3)	0.023 (2)	−0.003 (3)	−0.0027 (19)	−0.002 (2)
O3	0.025 (3)	0.020 (3)	0.0142 (19)	0.004 (2)	−0.002 (2)	−0.002 (2)
H11	0.035 (6)	0.028 (5)	0.052 (6)	−0.003 (5)	0.002 (5)	0.001 (5)
H12	0.053 (7)	0.041 (7)	0.033 (5)	0.002 (5)	−0.011 (5)	0.008 (5)
H21	0.027 (5)	0.040 (6)	0.058 (7)	0.005 (5)	−0.006 (5)	−0.002 (6)
H22	0.039 (6)	0.022 (5)	0.045 (6)	−0.007 (5)	−0.003 (5)	−0.004 (4)
H31	0.039 (6)	0.034 (6)	0.043 (5)	0.013 (5)	−0.002 (5)	0.002 (5)
H32	0.033 (5)	0.033 (6)	0.029 (5)	0.003 (5)	0.001 (4)	0.001 (4)
S	0.016 (4)	0.016 (4)	0.017 (5)	0.003 (5)	0.002 (3)	−0.002 (3)
O4	0.048 (4)	0.020 (3)	0.024 (2)	−0.010 (3)	0.006 (3)	0.001 (2)
O5	0.017 (3)	0.022 (3)	0.041 (3)	0.0042 (17)	−0.001 (3)	−0.004 (3)

Geometric parameters (Å, º)

Ni—O1^i	2.017 (7)	O2—H21	0.953 (15)
Ni—O1	2.017 (7)	O2—H22	0.973 (12)
Ni—O2	2.065 (6)	O3—H31	0.979 (13)
Ni—O2^i	2.065 (6)	O3—H32	0.978 (14)
Ni—O3^i	2.085 (5)	S—O4	1.469 (11)
Ni—O3	2.085 (5)	S—O4^i	1.469 (11)
O1—H11	0.928 (16)	S—O5^i	1.474 (11)
O1—H12	0.954 (13)	S—O5	1.474 (11)
O1^i—Ni—O1	90.8 (4)	Ni—O1—H11	125.2 (10)
O1^i—Ni—O2	178.7 (3)	Ni—O1—H12	121.9 (10)
O1—Ni—O2	88.1 (2)	H11—O1—H12	112.8 (13)
O1^i—Ni—O2^i	88.1 (2)	Ni—O2—H21	115.2 (9)
O1—Ni—O2^i	178.7 (3)	Ni—O2—H22	120.6 (9)
O2—Ni—O2^i	93.0 (4)	H21—O2—H22	110.4 (13)
O1^i—Ni—O3^i	89.7 (3)	Ni—O3—H31	110.7 (8)
O1—Ni—O3^i	90.3 (3)	Ni—O3—H32	115.2 (8)
O2—Ni—O3^i	90.9 (2)	H31—O3—H32	110.9 (12)
O2^i—Ni—O3^i	89.1 (2)	O4—S—O4^i	110.2 (12)
O1^i—Ni—O3	90.3 (3)	O4—S—O5^i	109.9 (4)
O1—Ni—O3	89.7 (3)	O4^i—S—O5^i	109.2 (4)
O2—Ni—O3	89.1 (2)	O4—S—O5	109.2 (4)
O2^i—Ni—O3	90.9 (2)	O4^i—S—O5	109.9 (4)
O3^i—Ni—O3	180.0 (5)	O5^i—S—O5	108.6 (12)

Symmetry code: (i) y, x, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···O5^ii	0.928 (16)	1.804 (15)	2.719 (10)	168.2 (14)
O1—H11···S^ii	0.928 (16)	2.82 (2)	3.691 (17)	157.1 (11)
O1—H12···O3^iii	0.954 (13)	1.848 (14)	2.791 (8)	168.9 (15)
O2—H21···O5^iv	0.953 (15)	1.884 (15)	2.775 (9)	154.6 (12)
O2—H22···O4	0.973 (12)	1.779 (13)	2.747 (9)	173.0 (14)
O2—H22···S	0.973 (12)	2.779 (19)	3.676 (16)	153.6 (10)
O3—H31···O5^v	0.979 (13)	1.899 (13)	2.820 (9)	155.6 (12)
O3—H31···S^v	0.979 (13)	2.780 (12)	3.741 (5)	167.1 (12)
O3—H32···O4^iii	0.978 (14)	1.757 (14)	2.725 (10)	170.3 (11)
O3—H32···S^iii	0.978 (14)	2.802 (12)	3.681 (7)	150.0 (9)

Symmetry codes: (ii) x−1, y−1, z; (iii) −x+1/2, y−1/2, −z+1/4; (iv) y, x−1, −z; (v) x−1, y, z.