Tetra­kis(μ-acetato-κ²O:O′)bis­[(tetra­hydro­furan-κO)chromium(II)]

The title compound, [Cr₂(C₂H₃O₂)₄(C₄H₈O)₂] or [Cr₂(OAc)₄(THF)₂] (OAc is acetate, THF is tetra­hydro­furan), was obtained by recrystallization of anhydrous chromium(II) acetate [Cr₂(OAc)₄] from hot tetra­hydro­furan. The centrosymmetric complex forms monoclinic crystals, space group C2/c, and consists of two Cr^II atoms bridged by four acetate ligands. Additionally, each Cr^II atom is coordinated by a terminal THF ligand, which leads to a square-pyramidal coordination.

Key indicators

Structure: I

• Single-crystal X-ray study
• T = 213 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.028
• wR factor = 0.084
• Data-to-parameter ratio = 17.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.11 Report
PLAT911_ALERT_3_C Missing FCF Refl Between Thmin & STh/L=    0.600          4 Report
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          4 Note

Alert level G
PLAT128_ALERT_4_G Alternate Setting for Input Space Group     C2/c       I2/c Note
PLAT883_ALERT_1_G No Info/Value for _atom_sites_solution_primary .     Please Do !
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Theta(Min).          1 Note
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         24 Note
PLAT933_ALERT_2_G Number of HKL-OMIT Records in Embedded .res File          1 Note
PLAT941_ALERT_3_G Average HKL Measurement Multiplicity ...........        3.5 Low
PLAT978_ALERT_2_G Number C-C Bonds with Positive Residual Density.          3 Info

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   7 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: X-AREA (Stoe, 2016); cell refinement: X-AREA (Stoe, 2016); data reduction: X-AREA (Stoe, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 2019; software used to prepare material for publication: Olex2 (Dolomanov et al., 2009).

Tetrakis(µ-acetato-κ²O:O')bis[(tetrahydrofuran-κO)chromium(II)](Cr—Cr)

Crystal data

[Cr2(C2H3O2)4(C4H8O)2]	F(000) = 1008
Mr = 484.38	Dx = 1.481 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 20.833 (4) Å	Cell parameters from 10024 reflections
b = 9.6413 (15) Å	θ = 1.9–27.1°
c = 15.654 (3) Å	µ = 1.05 mm^−1
β = 136.283 (10)°	T = 213 K
V = 2172.9 (7) Å^3	Block, clear red
Z = 4	0.19 × 0.16 × 0.14 mm

Data collection

Stoe IPDSII diffractometer	2297 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	2085 reflections with I > 2σ(I)
Plane graphite monochromator	Rint = 0.025
Detector resolution: 6.67 pixels mm^-1	θmax = 26.8°, θmin = 2.5°
rotation method, ω scans	h = −26→26
Absorption correction: integration [Absorption correction with X-Red32 (Stoe, 2009) by Gaussian integration analogous to Coppens (1970)]	k = −12→11
Tmin = 0.736, Tmax = 0.873	l = −19→19
8042 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.028	H-atom parameters constrained
wR(F^2) = 0.084	w = 1/[σ^2(Fo^2) + (0.0467P)^2 + 2.3382P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
2297 reflections	Δρmax = 0.54 e Å^−3
129 parameters	Δρmin = −0.25 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.

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

	x	y	z	Uiso*/Ueq
Cr	0.26094 (2)	0.66145 (3)	0.46117 (2)	0.02544 (11)
O4	0.14551 (9)	0.92201 (13)	0.36838 (12)	0.0342 (3)
O2	0.34181 (9)	0.94502 (13)	0.57992 (12)	0.0333 (3)
O1	0.36182 (9)	0.77547 (14)	0.50418 (12)	0.0345 (3)
O5	0.28145 (10)	0.47338 (14)	0.38969 (12)	0.0372 (3)
O3	0.16586 (9)	0.75243 (13)	0.29340 (11)	0.0323 (3)
C1	0.38244 (12)	0.8921 (2)	0.55545 (16)	0.0318 (4)
C7	0.2675 (2)	0.2300 (2)	0.3690 (3)	0.0598 (7)
H7A	0.256700	0.153198	0.399458	0.072*
H7B	0.302134	0.193893	0.352458	0.072*
C4	0.05644 (14)	0.9286 (2)	0.15474 (18)	0.0437 (5)
H4A	0.028412	1.008695	0.156494	0.065*
H4B	0.008049	0.860582	0.094730	0.065*
H4C	0.086525	0.959150	0.130761	0.065*
C6	0.17708 (19)	0.2950 (3)	0.2548 (2)	0.0557 (6)
H6A	0.149691	0.245473	0.179140	0.067*
H6B	0.131657	0.296526	0.258606	0.067*
C2	0.46056 (14)	0.9713 (2)	0.5899 (2)	0.0447 (5)
H2A	0.451210	1.070872	0.590081	0.067*
H2B	0.461851	0.951885	0.529713	0.067*
H2C	0.519618	0.942836	0.672441	0.067*
C5	0.20714 (15)	0.4391 (2)	0.25966 (19)	0.0396 (4)
H5A	0.229504	0.441548	0.221381	0.048*
H5B	0.154969	0.505239	0.215539	0.048*
C3	0.12762 (12)	0.86336 (19)	0.28110 (16)	0.0296 (4)
C8	0.31894 (19)	0.3462 (2)	0.4601 (2)	0.0537 (6)
H8A	0.310317	0.343141	0.514527	0.064*
H8B	0.386159	0.339342	0.512128	0.064*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr	0.02569 (16)	0.02424 (17)	0.02535 (16)	0.00141 (10)	0.01810 (14)	0.00139 (10)
O4	0.0342 (7)	0.0303 (6)	0.0301 (6)	0.0073 (5)	0.0206 (6)	0.0046 (5)
O2	0.0330 (6)	0.0300 (6)	0.0358 (7)	−0.0039 (5)	0.0245 (6)	−0.0014 (5)
O1	0.0324 (6)	0.0367 (7)	0.0387 (7)	−0.0011 (5)	0.0272 (6)	−0.0005 (6)
O5	0.0429 (7)	0.0283 (6)	0.0389 (7)	0.0034 (6)	0.0290 (6)	−0.0013 (5)
O3	0.0353 (6)	0.0321 (6)	0.0276 (6)	0.0030 (5)	0.0221 (6)	0.0024 (5)
C1	0.0269 (8)	0.0356 (9)	0.0257 (8)	−0.0001 (7)	0.0167 (7)	0.0068 (7)
C7	0.090 (2)	0.0343 (11)	0.0689 (16)	0.0016 (12)	0.0617 (16)	0.0012 (11)
C4	0.0388 (10)	0.0433 (11)	0.0299 (9)	0.0054 (9)	0.0185 (9)	0.0106 (8)
C6	0.0637 (15)	0.0443 (12)	0.0557 (14)	−0.0147 (11)	0.0420 (13)	−0.0109 (11)
C2	0.0333 (10)	0.0517 (12)	0.0432 (11)	−0.0084 (9)	0.0257 (9)	0.0034 (9)
C5	0.0444 (11)	0.0372 (10)	0.0373 (10)	0.0029 (8)	0.0296 (9)	−0.0014 (8)
C3	0.0245 (8)	0.0303 (8)	0.0264 (8)	−0.0014 (7)	0.0159 (7)	0.0038 (7)
C8	0.0604 (14)	0.0347 (11)	0.0486 (13)	0.0132 (10)	0.0336 (12)	0.0067 (9)

Geometric parameters (Å, º)

Cr—Cr^i	2.3242 (6)	C7—C8	1.492 (3)
Cr—O4^i	2.0121 (14)	C4—H4A	0.9800
Cr—O2^i	2.0146 (13)	C4—H4B	0.9800
Cr—O1	2.0083 (13)	C4—H4C	0.9800
Cr—O5	2.3267 (13)	C4—C3	1.506 (2)
Cr—O3	2.0175 (13)	C6—H6A	0.9900
O4—C3	1.261 (2)	C6—H6B	0.9900
O2—C1	1.262 (2)	C6—C5	1.503 (3)
O1—C1	1.263 (2)	C2—H2A	0.9800
O5—C5	1.447 (2)	C2—H2B	0.9800
O5—C8	1.444 (2)	C2—H2C	0.9800
O3—C3	1.262 (2)	C5—H5A	0.9900
C1—C2	1.501 (3)	C5—H5B	0.9900
C7—H7A	0.9900	C8—H8A	0.9900
C7—H7B	0.9900	C8—H8B	0.9900
C7—C6	1.506 (4)
Cr^i—Cr—O5	176.08 (4)	H4A—C4—H4C	109.5
O4^i—Cr—Cr^i	88.19 (4)	H4B—C4—H4C	109.5
O4^i—Cr—O2^i	90.40 (6)	C3—C4—H4A	109.5
O4^i—Cr—O5	89.29 (5)	C3—C4—H4B	109.5
O4^i—Cr—O3	177.16 (5)	C3—C4—H4C	109.5
O2^i—Cr—Cr^i	88.66 (4)	C7—C6—H6A	111.4
O2^i—Cr—O5	88.36 (5)	C7—C6—H6B	111.4
O2^i—Cr—O3	89.37 (6)	H6A—C6—H6B	109.2
O1—Cr—Cr^i	88.61 (4)	C5—C6—C7	101.9 (2)
O1—Cr—O4^i	89.91 (6)	C5—C6—H6A	111.4
O1—Cr—O2^i	177.24 (5)	C5—C6—H6B	111.4
O1—Cr—O5	94.38 (5)	C1—C2—H2A	109.5
O1—Cr—O3	90.19 (6)	C1—C2—H2B	109.5
O3—Cr—Cr^i	88.98 (4)	C1—C2—H2C	109.5
O3—Cr—O5	93.53 (5)	H2A—C2—H2B	109.5
C3—O4—Cr^i	120.14 (11)	H2A—C2—H2C	109.5
C1—O2—Cr^i	119.21 (12)	H2B—C2—H2C	109.5
C1—O1—Cr	119.57 (12)	O5—C5—C6	105.37 (17)
C5—O5—Cr	118.23 (11)	O5—C5—H5A	110.7
C8—O5—Cr	118.74 (13)	O5—C5—H5B	110.7
C8—O5—C5	108.56 (15)	C6—C5—H5A	110.7
C3—O3—Cr	118.98 (11)	C6—C5—H5B	110.7
O2—C1—O1	123.94 (17)	H5A—C5—H5B	108.8
O2—C1—C2	118.42 (18)	O4—C3—O3	123.71 (16)
O1—C1—C2	117.64 (18)	O4—C3—C4	118.37 (17)
H7A—C7—H7B	109.0	O3—C3—C4	117.92 (17)
C6—C7—H7A	111.0	O5—C8—C7	106.84 (19)
C6—C7—H7B	111.0	O5—C8—H8A	110.4
C8—C7—H7A	111.0	O5—C8—H8B	110.4
C8—C7—H7B	111.0	C7—C8—H8A	110.4
C8—C7—C6	103.9 (2)	C7—C8—H8B	110.4
H4A—C4—H4B	109.5	H8A—C8—H8B	108.6
Cr^i—O4—C3—O3	−0.4 (2)	Cr—O3—C3—O4	0.2 (2)
Cr^i—O4—C3—C4	179.40 (13)	Cr—O3—C3—C4	−179.60 (13)
Cr^i—O2—C1—O1	1.2 (2)	C7—C6—C5—O5	−34.4 (2)
Cr^i—O2—C1—C2	−178.35 (12)	C6—C7—C8—O5	−23.6 (3)
Cr—O1—C1—O2	−1.6 (2)	C5—O5—C8—C7	1.9 (3)
Cr—O1—C1—C2	177.88 (12)	C8—O5—C5—C6	20.7 (2)
Cr—O5—C5—C6	−118.42 (16)	C8—C7—C6—C5	35.1 (3)
Cr—O5—C8—C7	140.80 (18)

Symmetry code: (i) −x+1/2, −y+3/2, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4B···O1^ii	0.98	2.60	3.472 (3)	148

Symmetry code: (ii) x−1/2, −y+3/2, z−1/2.