2,2′-Di­propyl­malonic acid: intermolecular association via strong O—H...O hydrogen bonds

The molecular structure of the title compound, C₉H₁₆O₄, is described by a trans-planar configuration of the propyl chains. The mol­ecule has an approximate pseudo-twofold rotation axis in the crystal structure. The mol­ecules are interconnected by strong O—H...O hydrogen bonds and form an R₂²(8) ring structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.051
• wR factor = 0.150
• Data-to-parameter ratio = 17.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT022_ALERT_3_C Ratio Unique / Expected Reflections too Low ....       0.91
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 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
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Farrugia, 1997) and PLUTON (Spek, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and PARST (Nardelli, 1995).

2,2'-Dipropylmalonic acid

Crystal data

C9H16O4	Z = 2
Mr = 188.22	F(000) = 204
Triclinic, P1	Dx = 1.145 Mg m^−3
Hall symbol: -P 1	Melting point: 432 K
a = 7.683 (1) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.549 (1) Å	Cell parameters from 3369 reflections
c = 9.382 (1) Å	θ = 5–55°
α = 76.249 (2)°	µ = 0.09 mm^−1
β = 70.140 (2)°	T = 293 K
γ = 72.355 (2)°	Block, colourless
V = 546.05 (12) Å^3	0.55 × 0.22 × 0.12 mm

Data collection

Bruker SMART CCD area-detector diffractometer	2261 independent reflections
Radiation source: fine-focus sealed tube	1784 reflections with I > 2s(I)
Graphite monochromator	Rint = 0.014
ω scans	θmax = 27.4°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.977, Tmax = 0.989	k = −10→11
5840 measured reflections	l = −12→12

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)] = 0.051	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.150	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0805P)^2 + 0.0901P] where P = (Fo^2 + 2Fc^2)/3
2261 reflections	(Δ/σ)max < 0.001
126 parameters	Δρmax = 0.18 e Å^−3
0 restraints	Δρmin = −0.16 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.

Weighted least-squares planes through the starred atoms (Nardelli, Musatti, Domiano & Andreetti Ric·Sci.(1965),15(II—A),807). Equation of the plane: m1*X+m2*Y+m3*Z=d

Plane 1 m1 = -0.80858(0.00061) m2 = 0.58695(0.00074) m3 = -0.04113(0.00319) D = -2.45341(0.01993) Atom d s d/s (d/s)**2 C2 * -0.0049 0.0016 - 2.988 8.929 C7 * 0.0064 0.0019 3.405 11.596 C8 * 0.0165 0.0030 5.578 31.111 C9 * -0.0226 0.0035 - 6.509 42.367 C3 1.2007 0.0018 673.727 453907.656 C1 0.1351 0.0017 77.893 6067.362 ============ Sum((d/s)**2) for starred atoms 94.004 Chi-squared at 95% for 1 degrees of freedom: 3.84 The group of atoms deviates significantly from planarity

Plane 2 m1 = 0.66339(0.00070) m2 = 0.73921(0.00047) m3 = -0.11617(0.00266) D = 5.02160(0.01959) Atom d s d/s (d/s)**2 C2 * -0.0040 0.0016 - 2.454 6.023 C4 * 0.0048 0.0017 2.812 7.910 C5 * 0.0057 0.0020 2.791 7.791 C6 * -0.0109 0.0027 - 4.051 16.412 C1 - 1.2935 0.0017 - 758.805 575784.375 C3 - 0.0502 0.0017 - 28.886 834.402 ============ Sum((d/s)**2) for starred atoms 38.136 Chi-squared at 95% for 1 degrees of freedom: 3.84 The group of atoms deviates significantly from planarity

Plane 3 m1 = 0.56743(0.00075) m2 = 0.82342(0.00052) m3 = -0.00125(0.00084) D = 5.55989(0.00462) Atom d s d/s (d/s)**2 C2 * 0.0022 0.0016 1.355 1.837 C3 * -0.0088 0.0017 - 5.133 26.345 O2 * 0.0024 0.0016 1.523 2.321 O4 * 0.0022 0.0014 1.622 2.632 C7 1.3285 0.0018 750.870 563805.125 C4 - 0.2488 0.0017 - 147.142 21650.768 ============ Sum((d/s)**2) for starred atoms 33.135 Chi-squared at 95% for 1 degrees of freedom: 3.84 The group of atoms deviates significantly from planarity

Plane 4 m1 = 0.68202(0.00075) m2 = -0.72881(0.00070) m3 = -0.06078(0.00094) D = 0.67894(0.00888) Atom d s d/s (d/s)**2 C2 * 0.0026 0.0016 1.620 2.623 C1 * -0.0105 0.0017 - 6.119 37.447 O3 * 0.0032 0.0015 2.128 4.529 O1 * 0.0032 0.0016 1.942 3.773 C7 - 0.3378 0.0018 - 185.574 34437.633 C4 1.3846 0.0017 809.940 656002.313 ============ Sum((d/s)**2) for starred atoms 48.372 Chi-squared at 95% for 1 degrees of freedom: 3.84 The group of atoms deviates significantly from planarity

Dihedral angles formed by LSQ-planes Plane - plane angle (s.u.) angle (s.u.) 1 2 84.39 (0.06) 95.61 (0.06) 1 3 88.59 (0.06) 91.41 (0.06) 1 4 12.38 (0.11) 167.62 (0.11) 2 3 9.85 (0.11) 170.15 (0.11) 2 4 85.46 (0.06) 94.54 (0.06) 3 4 77.70 (0.06) 102.30 (0.06)

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
O1	0.0860 (2)	0.07364 (18)	0.79604 (14)	0.0766 (5)
O2	−0.03567 (18)	0.44811 (19)	0.71039 (15)	0.0784 (5)
O3	0.1097 (2)	0.13697 (17)	1.00235 (13)	0.0745 (4)
O4	0.20931 (16)	0.39020 (17)	0.50464 (12)	0.0706 (4)
C1	0.1404 (2)	0.1565 (2)	0.86526 (17)	0.0512 (4)
C2	0.2539 (2)	0.27809 (19)	0.75464 (16)	0.0491 (4)
C3	0.1413 (2)	0.3764 (2)	0.64235 (17)	0.0538 (4)
C4	0.4476 (2)	0.1756 (2)	0.66546 (17)	0.0533 (4)
H4A	0.4227	0.1063	0.6101	0.064*
H4B	0.5164	0.2520	0.5901	0.064*
C5	0.5761 (3)	0.0656 (2)	0.7608 (2)	0.0655 (5)
H5A	0.6061	0.1335	0.8142	0.079*
H5B	0.5093	−0.0116	0.8370	0.079*
C6	0.7584 (3)	−0.0302 (3)	0.6626 (3)	0.0911 (7)
H6A	0.8364	−0.0989	0.7261	0.137*
H6B	0.8259	0.0459	0.5884	0.137*
H6C	0.7291	−0.0988	0.6107	0.137*
C7	0.2733 (2)	0.3985 (2)	0.84349 (18)	0.0576 (4)
H7A	0.1474	0.4486	0.9053	0.069*
H7B	0.3481	0.3359	0.9127	0.069*
C8	0.3661 (4)	0.5356 (3)	0.7421 (3)	0.0910 (7)
H8A	0.4900	0.4855	0.6776	0.109*
H8B	0.2887	0.6007	0.6755	0.109*
C9	0.3916 (5)	0.6487 (3)	0.8279 (3)	0.1129 (9)
H9A	0.4502	0.7321	0.7566	0.169*
H9B	0.4715	0.5860	0.8918	0.169*
H9C	0.2694	0.7009	0.8905	0.169*
H1	0.026 (4)	0.006 (3)	0.856 (3)	0.108 (8)*
H2	−0.094 (4)	0.508 (3)	0.642 (3)	0.101 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.1062 (11)	0.0927 (10)	0.0492 (7)	−0.0677 (9)	−0.0236 (7)	0.0136 (6)
O2	0.0509 (7)	0.1039 (10)	0.0483 (7)	−0.0003 (6)	−0.0057 (5)	0.0108 (7)
O3	0.0966 (10)	0.0984 (10)	0.0427 (7)	−0.0646 (8)	−0.0189 (6)	0.0148 (6)
O4	0.0534 (7)	0.0920 (9)	0.0435 (7)	−0.0091 (6)	−0.0073 (5)	0.0107 (6)
C1	0.0504 (8)	0.0590 (9)	0.0436 (8)	−0.0238 (7)	−0.0150 (7)	0.0091 (6)
C2	0.0456 (8)	0.0553 (8)	0.0411 (8)	−0.0204 (7)	−0.0074 (6)	0.0057 (6)
C3	0.0475 (8)	0.0579 (9)	0.0445 (8)	−0.0185 (7)	−0.0054 (6)	0.0089 (6)
C4	0.0491 (9)	0.0610 (9)	0.0457 (8)	−0.0169 (7)	−0.0101 (7)	−0.0010 (7)
C5	0.0606 (10)	0.0743 (11)	0.0641 (11)	−0.0102 (8)	−0.0250 (8)	−0.0127 (9)
C6	0.0683 (13)	0.1114 (17)	0.0927 (15)	0.0091 (12)	−0.0359 (11)	−0.0354 (13)
C7	0.0573 (9)	0.0600 (10)	0.0492 (9)	−0.0237 (8)	−0.0031 (7)	−0.0028 (7)
C8	0.1131 (18)	0.0881 (14)	0.0772 (14)	−0.0656 (14)	−0.0043 (12)	−0.0034 (11)
C9	0.132 (2)	0.0840 (16)	0.124 (2)	−0.0580 (16)	−0.0058 (17)	−0.0237 (15)

Geometric parameters (Å, º)

O1—C1	1.297 (2)	C5—H5A	0.9700
O1—H1	0.83 (3)	C5—H5B	0.9700
O2—C3	1.313 (2)	C6—H6A	0.9600
O2—H2	0.88 (3)	C6—H6B	0.9600
O3—C1	1.2056 (18)	C6—H6C	0.9600
O4—C3	1.2093 (18)	C7—C8	1.517 (2)
C1—C2	1.5297 (19)	C7—H7A	0.9700
C2—C3	1.524 (2)	C7—H7B	0.9700
C2—C7	1.537 (2)	C8—C9	1.487 (3)
C2—C4	1.547 (2)	C8—H8A	0.9700
C4—C5	1.515 (2)	C8—H8B	0.9700
C4—H4A	0.9700	C9—H9A	0.9600
C4—H4B	0.9700	C9—H9B	0.9600
C5—C6	1.506 (3)	C9—H9C	0.9600
C1—O1—H1	113.2 (18)	H5A—C5—H5B	108.0
C3—O2—H2	110.4 (17)	C5—C6—H6A	109.5
O3—C1—O1	123.73 (14)	C5—C6—H6B	109.5
O3—C1—C2	123.18 (14)	H6A—C6—H6B	109.5
O1—C1—C2	113.06 (13)	C5—C6—H6C	109.5
C3—C2—C1	107.15 (12)	H6A—C6—H6C	109.5
C3—C2—C7	109.01 (13)	H6B—C6—H6C	109.5
C1—C2—C7	109.91 (12)	C8—C7—C2	114.01 (14)
C3—C2—C4	109.01 (12)	C8—C7—H7A	108.8
C1—C2—C4	107.97 (13)	C2—C7—H7A	108.8
C7—C2—C4	113.58 (13)	C8—C7—H7B	108.8
O4—C3—O2	123.42 (15)	C2—C7—H7B	108.8
O4—C3—C2	123.45 (14)	H7A—C7—H7B	107.6
O2—C3—C2	113.11 (13)	C9—C8—C7	114.15 (19)
C5—C4—C2	116.08 (13)	C9—C8—H8A	108.7
C5—C4—H4A	108.3	C7—C8—H8A	108.7
C2—C4—H4A	108.3	C9—C8—H8B	108.7
C5—C4—H4B	108.3	C7—C8—H8B	108.7
C2—C4—H4B	108.3	H8A—C8—H8B	107.6
H4A—C4—H4B	107.4	C8—C9—H9A	109.5
C6—C5—C4	111.42 (16)	C8—C9—H9B	109.5
C6—C5—H5A	109.3	H9A—C9—H9B	109.5
C4—C5—H5A	109.3	C8—C9—H9C	109.5
C6—C5—H5B	109.3	H9A—C9—H9C	109.5
C4—C5—H5B	109.3	H9B—C9—H9C	109.5
O3—C1—C2—C3	−133.23 (17)	C7—C2—C3—O2	−64.83 (17)
O1—C1—C2—C3	48.74 (18)	C4—C2—C3—O2	170.68 (14)
O3—C1—C2—C7	−14.9 (2)	C3—C2—C4—C5	−178.15 (14)
O1—C1—C2—C7	167.06 (14)	C1—C2—C4—C5	−62.07 (18)
O3—C1—C2—C4	109.48 (18)	C7—C2—C4—C5	60.09 (18)
O1—C1—C2—C4	−68.55 (17)	C2—C4—C5—C6	178.96 (16)
C1—C2—C3—O4	−127.53 (17)	C3—C2—C7—C8	−56.9 (2)
C7—C2—C3—O4	113.56 (18)	C1—C2—C7—C8	−174.03 (17)
C4—C2—C3—O4	−10.9 (2)	C4—C2—C7—C8	64.9 (2)
C1—C2—C3—O2	54.07 (18)	C2—C7—C8—C9	−177.9 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3^i	0.83 (3)	1.85 (3)	2.678 (2)	176 (3)
O2—H2···O4^ii	0.87 (3)	1.80 (3)	2.673 (2)	175 (3)

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