Bis[3-acetyl-6-methyl-2H-pyran-2,4(3H)-dionato]bis­(dimethyl sulfoxide)copper(II)

In the structure of the mononuclear title complex, [Cu(C₈H₇O₄)₂(C₂H₆OS)₂], the Cu^II atom lies on an inversion centre and has an octa­hedral coordination geometry of type MO₆. The bidentate dehydro­acetic acid (DHA) ligands occupy the equatorial plane of the complex in a trans configuration, and the dimethyl­sulfoxide (DMSO) ligands are weakly coordinated through their O atoms.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.035
• wR factor = 0.093
• Data-to-parameter ratio = 22.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Cu1    -   O5      ..       6.75 su

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

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

---

S1. Comment

Mixed d-transition metal–β-diketone compounds were used extensively as starting materials in the early days of metallocene chemistry (Smith & Andersen, 1996). Dehydroacetic acid [DHA, 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione], a commercially available compound usually obtained through the auto-condensation of ethyl acetoacetate (Arndt et al., 1936), has been shown to possess modest antifungal properties (Rao et al., 1978). The importance of similar pyrones as potential fungicides is reinforced by the existence of several natural fungicides possessing structures analogous to 5,6-dihydrodehydroacetic acid, such as alternaric acid (Bartels-Keith, 1960), the podoblastins (Miyakado et al., 1982) and lachnelluloic acid (Ayer et al., 1988). Also, it has been shown that the complexes of DHA with zinc and with several other transition metal cations are fungistatic (Rao et al., 1978). This has motivated our study of the structural characterization of complexes of dehydroacetic acid. The complex of DHA with Cu was previously reported by Casabò et al. (1987), but their characterization of the compound was based only on thermal and elemental analysis, and on IR and NMR spectroscopy. We present here the crystal structure determination of the title complex, [Cu(DHA)₂(DMSO)₂], (I) (DMSO is dimethylsulfoxide).

The Cu^II atom of (I), located on an inversion centre, is surrounded by two DHA ligands occupying the equatorial plane. The two apical positions are occupied by O atoms of two dimethylsulfoxyde molecules (Fig. 1). Complexes with related structures have been already reported with thiosemicarbazone 2-pyridineformamide (Castiñeiras et al., 2000), and thiosemicarbazone of acenaphthenequinone (Rodriguez-Argüelles et al., 1997).

The structure of (I) is isostructural with the two complexes [Zn(DHA)₂(DMSO)₂] and [Cd(DHA)₂(DMSO)₂] (Zucolotto Chalaça et al., 2002). The O5···Cu bond length for the DMSO in the copper complex, (I) (2.463 Å) is significantly longer than the Zn···O and Cd···O distances of 2.185 and 2.316 Å, respectively, found in the above complexes. This difference may be related to the tendancy of Cu to prefer a square-planar geometry.

The packing of (I) is stabilized by weak intermolecular C—H···O hydrogen bonds (Table 1) which form a three-dimensional network (Fig. 2).

S2. Experimental

A solution of copper acetate monohydrate was added, with stirring, to a solution of dehydroacetic acid in absolute ethanol in a 1:2 stoichiometric ratio. The title complex precipitated after 1 h. The resulting precipitate of (I) was filtered off and recrystallized by slow evaporation of a dimethylsulfoxide solution.

S3. Refinement

All H atoms were located in difference Fourier maps but introduced in calculated positions and treated as riding on their parent C atoms, with C—H distances of 0.96 Å (CH₃) and 0.93 Å (C_aromatic) and with U_iso(H) = 1.2U_eq(C_aromatic) or 1.5U_eq(CH₃).

Computing details

Data collection: KappaCCD (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. A view of the title compound, with the atomic labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity. [Symmetry code: (i) −x, −y, −z.]
	Fig. 2. A packing view, showing the C—H···O hydrogen-bond interactions (dashed lines).

(I)

Crystal data

[Cu(C8H7O4)2(C2H6OS)2]	F(000) = 574
Mr = 554.07	Dx = 1.532 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 11050 reflections
a = 11.580 (5) Å	θ = 2.1–30.1°
b = 6.320 (5) Å	µ = 1.14 mm^−1
c = 16.424 (5) Å	T = 294 K
β = 92.27 (5)°	Prism, blue
V = 1201.1 (11) Å^3	0.1 × 0.1 × 0.1 mm
Z = 2

Data collection

Nonius KappaCCD area-detector diffractometer	2651 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.040
Graphite monochromator	θmax = 30.1°, θmin = 2.1°
ϕ scans, and ω scans with κ offsets	h = −13→16
11050 measured reflections	k = −6→8
3506 independent reflections	l = −22→23

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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.093	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0438P)^2 + 0.1877P] where P = (Fo^2 + 2Fc^2)/3
3506 reflections	(Δ/σ)max < 0.001
155 parameters	Δρmax = 0.37 e Å^−3
0 restraints	Δρmin = −0.39 e Å^−3

Special details

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.

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

	x	y	z	Uiso*/Ueq
Cu1	0.5000	0.5000	0.5000	0.03410 (10)
S1	0.73751 (4)	0.21537 (7)	0.47488 (3)	0.04139 (13)
O1	0.45594 (10)	0.26689 (17)	0.43168 (7)	0.0370 (3)
O2	0.45847 (12)	0.1864 (2)	0.18715 (7)	0.0440 (3)
O3	0.55902 (15)	0.4706 (2)	0.16465 (9)	0.0545 (4)
O4	0.58586 (10)	0.62317 (18)	0.41185 (7)	0.0380 (3)
O5	0.67750 (12)	0.3121 (2)	0.54540 (8)	0.0490 (3)
C1	0.46505 (13)	0.2507 (2)	0.35549 (10)	0.0300 (3)
C2	0.41204 (15)	0.0666 (3)	0.31725 (11)	0.0352 (4)
H2	0.3803	−0.0375	0.3496	0.042*
C3	0.40800 (15)	0.0437 (3)	0.23720 (12)	0.0376 (4)
C4	0.51841 (15)	0.3628 (3)	0.21731 (11)	0.0372 (4)
C5	0.52246 (13)	0.3973 (2)	0.30415 (10)	0.0303 (3)
C6	0.58663 (14)	0.5735 (3)	0.33815 (10)	0.0315 (3)
C7	0.66346 (17)	0.7094 (3)	0.28811 (12)	0.0462 (4)
H7A	0.6168	0.7918	0.2503	0.069*
H7B	0.7147	0.6209	0.2586	0.069*
H7C	0.7079	0.8023	0.3234	0.069*
C8	0.35032 (19)	−0.1283 (3)	0.18953 (13)	0.0540 (5)
H8A	0.3185	−0.2294	0.2261	0.081*
H8B	0.4057	−0.1971	0.1565	0.081*
H8C	0.2894	−0.0698	0.1551	0.081*
C9	0.8695 (2)	0.3578 (3)	0.46739 (15)	0.0630 (6)
H9A	0.8531	0.4998	0.4497	0.095*
H9B	0.9170	0.2892	0.4287	0.095*
H9C	0.9095	0.3611	0.5197	0.095*
C10	0.7993 (2)	−0.0257 (3)	0.51126 (15)	0.0553 (5)
H10A	0.8419	−0.0004	0.5616	0.083*
H10B	0.8503	−0.0806	0.4717	0.083*
H10C	0.7389	−0.1264	0.5201	0.083*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.04192 (18)	0.03601 (16)	0.02500 (16)	−0.00903 (12)	0.00933 (12)	−0.00397 (11)
S1	0.0423 (3)	0.0479 (3)	0.0340 (2)	0.00514 (19)	0.00183 (19)	−0.00032 (19)
O1	0.0475 (7)	0.0372 (6)	0.0270 (6)	−0.0099 (5)	0.0111 (5)	−0.0032 (5)
O2	0.0546 (8)	0.0496 (7)	0.0277 (6)	−0.0116 (6)	0.0014 (6)	−0.0035 (5)
O3	0.0750 (10)	0.0616 (9)	0.0275 (7)	−0.0181 (7)	0.0111 (7)	0.0047 (6)
O4	0.0453 (7)	0.0405 (7)	0.0288 (6)	−0.0106 (5)	0.0089 (5)	−0.0028 (5)
O5	0.0473 (7)	0.0564 (8)	0.0440 (8)	0.0105 (6)	0.0104 (6)	−0.0034 (6)
C1	0.0293 (8)	0.0321 (8)	0.0289 (8)	0.0022 (6)	0.0052 (6)	−0.0010 (6)
C2	0.0368 (9)	0.0338 (8)	0.0356 (9)	−0.0034 (7)	0.0084 (7)	−0.0030 (7)
C3	0.0345 (9)	0.0401 (9)	0.0383 (10)	−0.0012 (7)	0.0014 (7)	−0.0054 (7)
C4	0.0396 (9)	0.0418 (9)	0.0303 (9)	−0.0017 (7)	0.0037 (7)	0.0000 (7)
C5	0.0301 (8)	0.0334 (8)	0.0278 (8)	0.0000 (6)	0.0055 (6)	0.0006 (6)
C6	0.0304 (8)	0.0339 (7)	0.0305 (9)	−0.0002 (6)	0.0061 (6)	0.0015 (7)
C7	0.0516 (11)	0.0503 (10)	0.0378 (10)	−0.0153 (8)	0.0151 (9)	0.0003 (8)
C8	0.0582 (12)	0.0557 (12)	0.0479 (12)	−0.0142 (10)	−0.0014 (10)	−0.0142 (10)
C9	0.0680 (14)	0.0525 (12)	0.0708 (16)	−0.0139 (10)	0.0307 (12)	−0.0054 (11)
C10	0.0646 (14)	0.0468 (11)	0.0557 (14)	0.0076 (9)	0.0167 (11)	0.0052 (9)

Geometric parameters (Å, º)

Cu1—O1	1.9091 (15)	C3—C8	1.483 (3)
Cu1—O1^i	1.9091 (15)	C4—C5	1.442 (2)
Cu1—O4^i	1.9506 (14)	C5—C6	1.439 (3)
Cu1—O4	1.9506 (14)	C6—C7	1.504 (2)
S1—O5	1.5040 (15)	C7—H7A	0.9600
S1—C10	1.776 (2)	C7—H7B	0.9600
S1—C9	1.782 (2)	C7—H7C	0.9600
O1—C1	1.264 (2)	C8—H8A	0.9600
O2—C3	1.367 (2)	C8—H8B	0.9600
O2—C4	1.394 (2)	C8—H8C	0.9600
O3—C4	1.210 (2)	C9—H9A	0.9600
O4—C6	1.2508 (19)	C9—H9B	0.9600
C1—C5	1.434 (2)	C9—H9C	0.9600
C1—C2	1.447 (2)	C10—H10A	0.9600
C2—C3	1.322 (3)	C10—H10B	0.9600
C2—H2	0.9300	C10—H10C	0.9600
O1—Cu1—O1^i	180.0	O4—C6—C5	123.12 (15)
O1—Cu1—O4^i	89.78 (6)	O4—C6—C7	114.35 (15)
O1^i—Cu1—O4^i	90.22 (6)	C5—C6—C7	122.50 (15)
O1—Cu1—O4	90.22 (6)	C6—C7—H7A	109.5
O1^i—Cu1—O4	89.78 (6)	C6—C7—H7B	109.5
O4^i—Cu1—O4	180.0	H7A—C7—H7B	109.5
O5—S1—C10	106.36 (10)	C6—C7—H7C	109.5
O5—S1—C9	105.76 (10)	H7A—C7—H7C	109.5
C10—S1—C9	96.98 (13)	H7B—C7—H7C	109.5
C1—O1—Cu1	127.85 (10)	C3—C8—H8A	109.5
C3—O2—C4	122.20 (14)	C3—C8—H8B	109.5
C6—O4—Cu1	129.90 (11)	H8A—C8—H8B	109.5
O1—C1—C5	126.05 (15)	C3—C8—H8C	109.5
O1—C1—C2	116.37 (15)	H8A—C8—H8C	109.5
C5—C1—C2	117.58 (15)	H8B—C8—H8C	109.5
C3—C2—C1	121.14 (16)	S1—C9—H9A	109.5
C3—C2—H2	119.4	S1—C9—H9B	109.5
C1—C2—H2	119.4	H9A—C9—H9B	109.5
C2—C3—O2	121.79 (16)	S1—C9—H9C	109.5
C2—C3—C8	127.07 (18)	H9A—C9—H9C	109.5
O2—C3—C8	111.14 (17)	H9B—C9—H9C	109.5
O3—C4—O2	113.46 (16)	S1—C10—H10A	109.5
O3—C4—C5	128.58 (17)	S1—C10—H10B	109.5
O2—C4—C5	117.94 (15)	H10A—C10—H10B	109.5
C1—C5—C6	121.08 (15)	S1—C10—H10C	109.5
C1—C5—C4	119.11 (15)	H10A—C10—H10C	109.5
C6—C5—C4	119.79 (14)	H10B—C10—H10C	109.5

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O5^ii	0.93	2.55	3.475 (3)	170
C9—H9B···O3^iii	0.96	2.55	3.394 (3)	146
C10—H10B···O3^iii	0.96	2.53	3.379 (3)	147
C10—H10C···O1^ii	0.96	2.58	3.486 (3)	158

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