(RS)-2-Methyl­glutaric acid

In the crystal structure of the title compound, C₆H₁₀O₄, the mol­ecules form chains via centrosymmetrically related pairs of strong O—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.050
• wR factor = 0.157
• Data-to-parameter ratio = 17.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       1.26
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal (x 10000)        3000 Deg.
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C5

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      1.260
            Tmax scaled      0.978 Tmin scaled      0.885
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

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

---

Computing details

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

(RS)-2-Methylglutaric acid

Crystal data

C6H10O4	Z = 2
Mr = 146.14	F(000) = 156
Triclinic, P1	Dx = 1.321 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.1765 (10) Å	Cell parameters from 2367 reflections
b = 5.7929 (12) Å	θ = 3.1–27.5°
c = 13.335 (3) Å	µ = 0.11 mm^−1
α = 80.92 (3)°	T = 293 K
β = 83.54 (3)°	Block, colorless
γ = 68.82 (3)°	0.33 × 0.21 × 0.2 mm
V = 367.52 (15) Å^3

Data collection

Rigaku R-AXIS RAPID diffractometer	1605 independent reflections
Radiation source: fine-focus sealed tube	1007 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
Detector resolution: 0 pixels mm^-1	θmax = 27.5°, θmin = 3.1°
ω scans	h = −6→6
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −7→7
Tmin = 0.702, Tmax = 0.776	l = −17→17
3517 measured reflections

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.157	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0694P)^2 + 0.0734P] where P = (Fo^2 + 2Fc^2)/3
1605 reflections	(Δ/σ)max < 0.001
91 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.19 e Å^−3

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

	x	y	z	Uiso*/Ueq
O1	1.0121 (4)	0.2213 (3)	0.07929 (13)	0.0766 (6)
H1	1.1084	0.1612	0.0283	0.092*
O2	0.7343 (4)	0.0074 (3)	0.08234 (13)	0.0740 (6)
O3	0.8019 (4)	−0.4989 (3)	0.42035 (13)	0.0804 (6)
H3	0.7525	−0.6051	0.4602	0.097*
O4	0.3877 (4)	−0.2059 (4)	0.44184 (14)	0.0835 (6)
C1	0.8039 (4)	0.1579 (4)	0.11706 (15)	0.0476 (5)
C2	0.6500 (4)	0.2884 (4)	0.20618 (16)	0.0538 (5)
H2A	0.7817	0.3269	0.2420	0.065*
C3	0.5202 (4)	0.1283 (4)	0.28057 (16)	0.0567 (6)
H3A	0.4108	0.2251	0.3336	0.068*
H3B	0.3961	0.0820	0.2452	0.068*
C4	0.7354 (5)	−0.1053 (5)	0.32858 (18)	0.0661 (6)
H4A	0.8458	−0.1989	0.2748	0.079*
H4B	0.8585	−0.0568	0.3636	0.079*
C5	0.6236 (5)	−0.2726 (5)	0.40178 (16)	0.0601 (6)
C6	0.4319 (5)	0.5335 (4)	0.1652 (2)	0.0722 (7)
H6A	0.5206	0.6312	0.1192	0.087*
H6B	0.3369	0.6245	0.2207	0.087*
H6C	0.3008	0.4992	0.1298	0.087*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0810 (11)	0.1031 (13)	0.0695 (11)	−0.0585 (10)	0.0306 (9)	−0.0405 (10)
O2	0.0881 (12)	0.0950 (12)	0.0628 (10)	−0.0592 (11)	0.0278 (8)	−0.0364 (9)
O3	0.0754 (12)	0.0827 (12)	0.0659 (11)	−0.0170 (10)	0.0086 (8)	0.0057 (9)
O4	0.0659 (11)	0.0904 (12)	0.0753 (12)	−0.0188 (9)	0.0150 (9)	0.0100 (9)
C1	0.0505 (11)	0.0522 (11)	0.0421 (10)	−0.0221 (9)	0.0019 (8)	−0.0054 (8)
C2	0.0526 (11)	0.0622 (12)	0.0508 (12)	−0.0230 (10)	0.0054 (9)	−0.0183 (10)
C3	0.0541 (12)	0.0699 (14)	0.0448 (11)	−0.0212 (11)	0.0083 (9)	−0.0130 (10)
C4	0.0568 (13)	0.0829 (16)	0.0532 (13)	−0.0223 (12)	0.0047 (10)	−0.0040 (11)
C5	0.0604 (13)	0.0764 (15)	0.0402 (11)	−0.0212 (12)	−0.0015 (9)	−0.0061 (10)
C6	0.0715 (16)	0.0587 (14)	0.0838 (18)	−0.0214 (12)	0.0084 (13)	−0.0141 (12)

Geometric parameters (Å, º)

O1—C1	1.287 (2)	C3—C4	1.510 (3)
O1—H1	0.8400	C3—H3A	0.9700
O2—C1	1.223 (3)	C3—H3B	0.9700
O3—C5	1.307 (3)	C4—C5	1.485 (3)
O3—H3	0.8400	C4—H4A	0.9700
O4—C5	1.226 (3)	C4—H4B	0.9700
C1—C2	1.501 (3)	C6—H6A	0.9600
C2—C3	1.518 (3)	C6—H6B	0.9600
C2—C6	1.525 (3)	C6—H6C	0.9600
C2—H2A	0.9800
C1—O1—H1	121.2	H3A—C3—H3B	107.9
C5—O3—H3	119.0	C5—C4—C3	115.31 (19)
O2—C1—O1	122.95 (19)	C5—C4—H4A	108.4
O2—C1—C2	122.82 (18)	C3—C4—H4A	108.4
O1—C1—C2	114.22 (18)	C5—C4—H4B	108.4
C1—C2—C3	112.24 (17)	C3—C4—H4B	108.4
C1—C2—C6	107.94 (19)	H4A—C4—H4B	107.5
C3—C2—C6	111.51 (18)	O4—C5—O3	122.8 (2)
C1—C2—H2A	108.3	O4—C5—C4	123.6 (2)
C3—C2—H2A	108.3	O3—C5—C4	113.54 (19)
C6—C2—H2A	108.3	C2—C6—H6A	109.5
C4—C3—C2	112.22 (17)	C2—C6—H6B	109.5
C4—C3—H3A	109.2	H6A—C6—H6B	109.5
C2—C3—H3A	109.2	C2—C6—H6C	109.5
C4—C3—H3B	109.2	H6A—C6—H6C	109.5
C2—C3—H3B	109.2	H6B—C6—H6C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2^i	0.84	1.84	2.671 (2)	167
O3—H3···O4^ii	0.84	1.83	2.661 (3)	171

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