Structures of strontium diformate and strontium fumarate. A synchrotron powder diffraction study

The crystal structures of strontium diformate in space groups P2₁2₁2₁ (α form, 295 K), P4₁2₁2 (β form, 334 and 540 K) and I4₁/amd (δ form, 605 K), and strontium fumarate in space groups Fddd (β form, 105 K) and I4₁/amd (α form, 293 K) have been determined from synchrotron X-ray powder diffraction data. Except for the α-strontium diformate, all the structures are based on a diamond-like Sr-ion arrangement, as in strontium acetylene dicarboxylate. The formate ions are disordered in the δ phase owing to steric hindrance. The fumarate ions are disordered over four (α) or two (β) symmetry-equivalent orientations. α-Strontium fumarate crystallizes with a unique 90° carboxylate dihedral angle, and is stable up to 773 K.

Computing details

For all compounds, data collection: Huber G670; cell refinement: WINPOW, local Rietveld program; data reduction: WINPOW, local Rietveld program; program(s) used to solve structure: EXPO, Altomari et al., 1994, 1995; program(s) used to refine structure: WINPOW, local Rietveld program; molecular graphics: ATOMS 6.2, Shape Software, USA; software used to prepare material for publication: WINPOW, local Rietveld program.

(alphastrontiumdiformate293K) Strontium diformate

Crystal data

C2H2O4Sr	Z = 4
Mr = 177.66	F(000) = 336.0
Orthorhombic, P212121	Dx = 2.704 Mg m^−3
Hall symbol: P 2ac 2ab	Synchrotron radiation, λ = 1.28406 Å
a = 6.86744 (3) Å	µ = 9.63 mm^−1
b = 8.75087 (4) Å	T = 293 K
c = 7.26091 (3) Å	colorless
V = 436.35 (1) Å^3	cylinder, 2.0 × 0.3 mm

Data collection

HUBER G670 Guinier camera diffractometer	Scan method: step
Radiation source: Synchrotron, Beamline 711, MAX II, Lund, Sweden	Absorption correction: for a cylinder mounted on the φ axis Bond, W.L. (1972) Int. Tabl. Vol II
Si(111) monochromator	Tmin = 0.327, Tmax = 0.368
Specimen mounting: quartz capillary	2θmin = 12.005°, 2θmax = 100.000°, 2θstep = 0.005°
Data collection mode: transmission

Refinement

Refinement on Inet	55 parameters
Least-squares matrix: full	0 restraints
Rp = 0.028	0 constraints
Rwp = 0.038	H-atom parameters not refined
Rexp = 0.007	Weighting scheme based on measured s.u.'s
RBragg = 0.023	(Δ/σ)max = 0.019
17600 data points	Background function: Chebyshev polynomial
Profile function: pseudo-Voigt

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

	x	y	z	Uiso*/Ueq
Sr	0.74509 (11)	0.58551 (4)	0.49192 (8)	0.01261 (15)*
C1	0.3516 (5)	0.5488 (5)	0.6931 (6)	0.0138 (4)*
O1	0.4977 (3)	0.4744 (4)	0.7515 (6)	0.0138 (4)*
O2	0.3683 (3)	0.6433 (3)	0.5663 (3)	0.0138 (4)*
C2	0.5222 (9)	0.2367 (8)	0.3957 (5)	0.0138 (4)*
O3	0.4119 (5)	0.1486 (4)	0.3319 (5)	0.0138 (4)*
O4	0.6093 (5)	0.3352 (4)	0.3112 (5)	0.0138 (4)*
H1	0.23278	0.53403	0.74441	0.0201 (4)*
H2	0.54251	0.23213	0.51833	0.0201 (4)*

Geometric parameters (Å, º)

Sr—O1^i	2.538 (3)	Sr—O4	2.719 (4)
Sr—O2^ii	2.555 (2)	C1—H1	0.906 (4)
Sr—O4^iii	2.619 (4)	C1—O2	1.243 (5)
Sr—O3^iv	2.645 (4)	C1—O1	1.269 (5)
Sr—O3^v	2.673 (4)	C2—H2	0.902 (3)
Sr—O2	2.691 (2)	C2—O3	1.176 (7)
Sr—O1	2.718 (3)	C2—O4	1.216 (7)
O1—C1—O2	121.1 (3)	O3—C2—O4	125.7 (4)
O1—C1—H1	120.1 (4)	O3—C2—H2	117.4 (6)
O2—C1—H1	118.9 (4)	O4—C2—H2	116.9 (6)

Symmetry codes: (i) −x+3/2, −y+1, z−1/2; (ii) x+1/2, −y+3/2, −z+1; (iii) −x+3/2, −y+1, z+1/2; (iv) −x+1, y+1/2, −z+1/2; (v) x+1/2, −y+1/2, −z+1.

(betastrontiumdiformate334K) Strontium diformate

Crystal data

C2H2O4Sr	F(000) = 336.0
Mr = 177.66	Dx = 2.416 Mg m^−3
Tetragonal, P41212	Synchrotron radiation, λ = 1.28406 Å
Hall symbol: P 4abw 2nw	µ = 8.60 mm^−1
a = 7.13577 (17) Å	T = 334 K
c = 9.5908 (3) Å	colorless
V = 488.36 (2) Å^3	cylinder, 2.0 × 0.3 mm
Z = 4

Data collection

HUBER G670 Guinier camera diffractometer	Scan method: step
Radiation source: Synchrotron, Beamline 711, MAX II, Lund, Sweden	Absorption correction: for a cylinder mounted on the φ axis Bond, W.L. (1972) Int. Tabl. Vol II
Si(111) monochromator	Tmin = 0.354, Tmax = 0.397
Specimen mounting: quartz capillary	2θmin = 12.001°, 2θmax = 100.006°, 2θstep = 0.005°
Data collection mode: transmission

Refinement

Refinement on Inet	38 parameters
Least-squares matrix: full	0 restraints
Rp = 0.032	0 constraints
Rwp = 0.050	H-atom parameters not refined
Rexp = 0.004	Weighting scheme based on measured s.u.'s
RBragg = 0.013	(Δ/σ)max = 0.031
17600 data points	Background function: Chebyshev polynomial
Profile function: Voigt	Preferred orientation correction: Icorr = Iobs/[P^2cos^2α + P^-1sin^2α]^3/2 (Dollase (1986) J. Appl. Cryst. 19, 267) P = 1.149(3) in direction (111)

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

	x	y	z	Uiso*/Ueq
Sr1	0.28072 (9)	0.28072 (9)	0.5000	0.0235 (4)*
C	0.2866 (11)	0.1901 (10)	0.1834 (5)	0.0364 (8)*
O1	0.4423 (4)	0.2153 (8)	0.2541 (6)	0.0364 (8)*
O2	0.1174 (5)	0.2215 (9)	0.2229 (4)	0.0364 (8)*
H	0.2995	0.1396	0.0971	0.0427 (8)*

Geometric parameters (Å, º)

Sr1—O1^i	2.415 (3)	Sr1—O2^v	2.932 (4)
Sr1—O1^ii	2.415 (3)	Sr1—O2	2.932 (4)
Sr1—O2^iii	2.417 (4)	C—H	0.907 (5)
Sr1—O2^iv	2.417 (4)	C—O2	1.285 (8)
Sr1—O1^v	2.666 (5)	C—O1	1.314 (8)
Sr1—O1	2.666 (5)
O1—C—O2	128.2 (5)	O2—C—H	115.7 (7)
O1—C—H	116.1 (7)

Symmetry codes: (i) −y+1/2, x−1/2, z+1/4; (ii) x−1/2, −y+1/2, −z+3/4; (iii) −y+1/2, x+1/2, z+1/4; (iv) x+1/2, −y+1/2, −z+3/4; (v) y, x, −z+1.

(betastrontiumdiformate540K) Strontium diformate

Crystal data

C2H2O4Sr	F(000) = 336.0
Mr = 177.66	Dx = 2.331 Mg m^−3
Tetragonal, P41212	Synchrotron radiation, λ = 1.28406 Å
Hall symbol: P 4abw 2nw	µ = 8.30 mm^−1
a = 7.09951 (7) Å	T = 540 K
c = 10.04048 (13) Å	colorless
V = 506.07 (1) Å^3	cylinder, 2.0 × 0.3 mm
Z = 4

Data collection

HUBER G670 Guinier camera diffractometer	Scan method: step
Radiation source: Synchrotron, Beamline 711, MAX II, Lund, Sweden	Absorption correction: for a cylinder mounted on the φ axis Bond, W.L. (1972) Int. Tabl. Vol II
Si(111) monochromator	Tmin = 0.354, Tmax = 0.397
Specimen mounting: quartz capillary	2θmin = 12.006°, 2θmax = 100.001°, 2θstep = 0.005°
Data collection mode: transmission

Refinement

Refinement on Inet	39 parameters
Least-squares matrix: full	0 restraints
Rp = 0.024	0 constraints
Rwp = 0.036	H-atom parameters not refined
Rexp = 0.005	Weighting scheme based on measured s.u.'s
RBragg = 0.009	(Δ/σ)max = 0.031
17600 data points	Background function: Chebyshev
Profile function: Voigt	Preferred orientation correction: Icorr = Iobs/[P^2cos^2α + P^-1sin^2α]^3/2 (Dollase (1986) J. Appl. Cryst. 19, 267) P = 1.080(5) in direction (111)

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

	x	y	z	Uiso*/Ueq
Sr1	0.26354 (11)	0.26354 (11)	0.5000	0.0580 (4)*
C	0.2877 (12)	0.2768 (10)	0.1937 (5)	0.0633*
O1	0.4134 (6)	0.2070 (11)	0.2584 (5)	0.0633*
O2	0.1218 (7)	0.2007 (8)	0.2260 (4)	0.0633*
H	0.3047	0.3723	0.1333	0.0697*

Geometric parameters (Å, º)

Sr1—O1^i	2.496 (4)	Sr1—O2^v	2.963 (5)
Sr1—O1^ii	2.496 (4)	Sr1—O2	2.963 (5)
Sr1—O2^iii	2.568 (5)	C—H	0.917 (6)
Sr1—O2^iv	2.568 (5)	C—O1	1.210 (9)
Sr1—O1^v	2.679 (5)	C—O2	1.336 (10)
Sr1—O1	2.679 (5)
O1—C—O2	110.7 (6)	O2—C—H	125.2 (8)
O1—C—H	124.1 (9)

Symmetry codes: (i) −y+1/2, x−1/2, z+1/4; (ii) x−1/2, −y+1/2, −z+3/4; (iii) −y+1/2, x+1/2, z+1/4; (iv) x+1/2, −y+1/2, −z+3/4; (v) y, x, −z+1.

(deltastrontiumdiformate605K) Strontium diformate

Crystal data

C2H2O4Sr	F(000) = 336.0
Mr = 177.66	Dx = 2.308 Mg m^−3
Tetragonal, I41/amd	Synchrotron radiation, λ = 1.28406 Å
Hall symbol: -I 4bd 2	µ = 8.21 mm^−1
a = 7.09042 (10) Å	T = 605 K
c = 10.16973 (15) Å	colorless
V = 511.27 (1) Å^3	cylinder, 2.0 × 0.3 mm
Z = 4

Data collection

HUBER G670 Guinier camera diffractometer	Scan method: step
Radiation source: Synchrotron, Beamline 711, MAX II, Lund, Sweden	Absorption correction: for a cylinder mounted on the φ axis Bond, W.L. (1972) Int. Tabl. Vol II
Si(111) monochromator	Tmin = 0.354, Tmax = 0.397
Specimen mounting: quartz capillary	2θmin = 12.002°, 2θmax = 99.997°, 2θstep = 0.005°
Data collection mode: transmission

Refinement

Refinement on Inet	34 parameters
Least-squares matrix: full	0 restraints
Rp = 0.025	0 constraints
Rwp = 0.041	H-atom parameters not refined
Rexp = 0.005	Weighting scheme based on measured s.u.'s
RBragg = 0.020	(Δ/σ)max = 0.043
17600 data points	Background function: Chebyshev polynomial
Profile function: Voigt	Preferred orientation correction: Icorr = Iobs/[P^2cos^2α + P^-1sin^2α]^3/2 (Dollase (1986) J. Appl. Cryst. 19, 267) P = 1.16(3) in direction (111)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sr1	0.0000	0.2500	0.3750	0.0569 (3)*
C2	0.0000	0.3132 (11)	0.0622 (5)	0.1011 (10)*	.5000
O1	0.1561 (3)	0.2500	0.1179 (2)	0.1011 (10)*
H	0.0000	0.3914	−0.0103	0.1074 (10)*	.5000

Geometric parameters (Å, º)

Sr1—O1^i	2.4398 (19)	Sr1—O1^vii	2.840 (2)
Sr1—O1^ii	2.4398 (19)	Sr1—O1	2.840 (2)
Sr1—O1^iii	2.4398 (19)	C2—H	0.922 (6)
Sr1—O1^iv	2.4398 (19)	C2—O1^vii	1.321 (4)
Sr1—O1^v	2.840 (2)	C2—O1	1.321 (4)
Sr1—O1^vi	2.840 (2)
O1—C2—O1^vii	113.7 (5)	O1^vii—C2—H	123.1 (2)
O1—C2—H	123.1 (2)

Symmetry codes: (i) −y+1/4, x−1/4, z+1/4; (ii) y−1/4, −x+3/4, z+1/4; (iii) x−1/2, y, −z+1/2; (iv) −x+1/2, −y+1/2, −z+1/2; (v) −y+1/4, x+1/4, −z+3/4; (vi) y−1/4, −x+1/4, −z+3/4; (vii) −x, −y+1/2, z.

(betastrontiumfumarate105K) Strontium fumarate

Crystal data

C4H2O4Sr	Z = 8
Mr = 201.68	F(000) = 768.0
Orthorhombic, Fddd	Dx = 2.573 Mg m^−3
Hall symbol: -F 2uv 2vw	Synchrotron radiation, λ = 1.25176 Å
a = 10.59801 (10) Å	µ = 7.58 mm^−1
b = 9.81628 (9) Å	T = 105 K
c = 10.00739 (8) Å	colorless
V = 1041.10 (2) Å^3	cylinder, 2.0 × 0.3 mm

Data collection

HUBER G670 Guinier camera diffractometer	Scan method: step
Radiation source: Synchrotron, Beamline 711, MAX II, Lund, Sweden	Absorption correction: for a cylinder mounted on the φ axis Bond, W.L. (1972) Int. Tabl. Vol II
Si(111) monochromator	Tmin = 0.423, Tmax = 0.452
Specimen mounting: quartz capillary	2θmin = 10.996°, 2θmax = 99.996°, 2θstep = 0.005°
Data collection mode: transmission

Refinement

Refinement on Inet	35 parameters
Least-squares matrix: full	0 restraints
Rp = 0.043	0 constraints
Rwp = 0.059	H-atom parameters not refined
Rexp = 0.008	Weighting scheme based on measured s.u.'s
RBragg = 0.034	(Δ/σ)max = 0.045
17800 data points	Background function: Chebyshev polynomial
Profile function: pseudo-Voigt	Preferred orientation correction: Icorr = Iobs/[P^2cos^2α + P^-1sin^2α]^3/2 (Dollase (1986) J. Appl. Cryst. 19, 267) P = 1.031(11) in direction (011)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sr	0.1250	0.1250	0.1250	0.00413 (17)*
O1	0.04418 (11)	0.19330 (12)	0.38019 (13)	0.0124 (4)*
C1	0.1250	0.1250	0.4332 (3)	0.0124 (4)*
C2	0.1724 (3)	0.1514 (4)	0.5847 (3)	0.0124 (4)*	.5000
H	0.2526	0.1665	0.6076	0.0188 (4)*	.5000

Geometric parameters (Å, º)

Sr—O1^i	2.5296 (12)	Sr—O1^vii	2.7758 (13)
Sr—O1^ii	2.5296 (12)	C1—O1	1.2101 (16)
Sr—O1^iii	2.5296 (12)	C1—O1^vii	1.2101 (16)
Sr—O1^iv	2.5296 (12)	C1—C2	1.618 (4)
Sr—O1	2.7758 (13)	C2—H	0.892 (3)
Sr—O1^v	2.7758 (13)	C2—C2^viii	1.289 (6)
Sr—O1^vi	2.7758 (13)
O1—C1—O1^vii	128.0 (2)	C1—C2—H	124.2 (3)
O1—C1—C2	122.80 (18)	C1—C2—H^ix	124.8 (3)

Symmetry codes: (i) −x, −y+1/2, −z+1/2; (ii) −x, y−1/4, z−1/4; (iii) x+1/4, y−1/4, −z+1/2; (iv) x+1/4, −y+1/2, z−1/4; (v) −x+1/4, y, −z+1/4; (vi) x, −y+1/4, −z+1/4; (vii) −x+1/4, −y+1/4, z; (viii) −x+1/4, y, −z+5/4; (ix) x, −y+1/4, −z+5/4.

(alphastrontiumfumarate293K) Strontium diformate

Crystal data

C4H2O4Sr	F(000) = 384.0
Mr = 201.68	Dx = 2.547 Mg m^−3
Tetragonal, I41/amd	Synchrotron radiation, λ = 1.25176 Å
Hall symbol: -I 4bd 2	µ = 7.51 mm^−1
a = 7.24689 (5) Å	T = 293 K
c = 10.01133 (7) Å	colorless
V = 525.77 (1) Å^3	cylinder, 2.0 × 0.3 mm
Z = 4

Data collection

HUBER G670 Guinier camera diffractometer	Scan method: step
Radiation source: Synchrotron, Beamline 711, MAX II, Lund, Sweden	Absorption correction: for a cylinder mounted on the φ axis Bond, W.L. (1972) Int. Tabl. Vol II
Si(111) monochromator	Tmin = 0.423, Tmax = 0.452
Specimen mounting: quartz capillary	2θmin = 10.997°, 2θmax = 99.992°, 2θstep = 0.005°
Data collection mode: transmission

Refinement

Refinement on Inet	36 parameters
Least-squares matrix: full	0 restraints
Rp = 0.047	0 constraints
Rwp = 0.064	H-atom parameters not refined
Rexp = 0.007	Weighting scheme based on measured s.u.'s
RBragg = 0.035	(Δ/σ)max = 0.024
17800 data points	Background function: Chebyshev polynomial
Profile function: pseudo-Voigt	Preferred orientation correction: Icorr = Iobs/[P^2cos^2α + P^-1sin^2α]^3/2 (Dollase (1986) J. Appl. Cryst. 19, 267) P = 1.082(14) in direction (111)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sr1	0.0000	0.2500	0.3750	0.00907 (17)*
C1	0.0000	0.2500	0.0598 (2)	0.0116 (4)*
C2	0.0162 (16)	0.3128 (5)	−0.0836 (3)	0.0116 (4)*	.2500
O1	0.14672 (14)	0.2780 (3)	0.11957 (12)	0.0116 (4)*	.5000
H	0.0951	0.4077	−0.1056	0.0179 (4)*	.2500

Geometric parameters (Å, º)

Sr1—O1^i	2.5688 (10)	Sr1—O1	2.7769 (12)
Sr1—O1^ii	2.5688 (10)	C1—O1^viii	1.2368 (15)
Sr1—O1^iii	2.5688 (10)	C1—O1^v	1.2368 (15)
Sr1—O1^iv	2.5688 (10)	C1—C2^viii	1.511 (3)
Sr1—O1^v	2.7769 (12)	C2—H	0.921 (8)
Sr1—O1^vi	2.7769 (12)	C2—C2^ix	1.062 (5)
Sr1—O1^vii	2.7769 (12)
O1—C1—O1^viii	122.2 (2)	C1—C2—C2^ix	127.1 (4)
C2—C1—O1^viii	125.2 (4)	C1—C2—H	120.0 (5)
C2—C1—O1^vii	116.3 (4)

Symmetry codes: (i) y−1/4, −x+3/4, z+1/4; (ii) −x+1/2, −y+1/2, −z+1/2; (iii) −y+1/4, −x+3/4, z+1/4; (iv) −x+1/2, y, −z+1/2; (v) −x, y, z; (vi) −y+1/4, x+1/4, −z+3/4; (vii) x, −y+1/2, z; (viii) −x, −y+1/2, z; (ix) −y+1/4, x+1/4, −z−1/4.