N-(4-Methyl-2-nitro­phen­yl)succinamic acid

Chaithanya, U.; Foro, S.; Gowda, B.T.

doi:10.1107/S1600536812007258

organic compounds

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ISSN: 2056-9890

Volume 68| Part 3| March 2012| Page o819

doi:10.1107/S1600536812007258

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N-(4-Methyl-2-nitrophenyl)succinamic acid

U. Chaithanya,^a Sabine Foro ^b and B. Thimme Gowda ^a ^*

^aDepartment of Chemistry, Mangalore University, Mangalagangotri 574 199, Mangalore, India, and ^bInstitute of Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt, Germany
^*Correspondence e-mail: gowdabt@yahoo.com

(Received 15 February 2012; accepted 17 February 2012; online 24 February 2012)

In the title compound, C₁₁H₁₂N₂O₅, the conformation of the N—H bond in the amide segment is syn to the ortho-nitro group in the benzene ring. The amide C=O and the carboxyl C=O of the acid segment are syn to each other and both are anti to the H atoms on the adjacent –CH₂ groups. Furthermore, the C=O and O—H bonds of the acid group are in syn positions with respect to each other. The dihedral angle between the benzene ring and the amide group is 36.1 (1)°. The amide H atom shows bifurcated intramolecular hydrogen bonding with an O atom of the ortho-nitro group and an intermolecular hydrogen bond with the carbonyl O atom of another molecule. In the crystal, the N—H⋯O(C) hydrogen bonds generate a chain running along the [100] direction. Inversion dimers are formed via a pair of O—H⋯O(C) interactions, that form an eight-membered hydrogen-bonded ring involving the carboxyl group.

Related literature

For our studies on the effects of substituents on the structures and other aspects of N-(aryl)-amides, see: Gowda et al. (1999 , 2006 ); Chaithanya et al. (2012 ). For N-(aryl)-methanesulfonamides, see: Gowda et al. (2007 ). For N-chloroarylamides, see: Jyothi & Gowda (2004 ). For N-bromoarylsulfonamides, see: Usha & Gowda (2006 ).

Experimental

Crystal data

C₁₁H₁₂N₂O₅
M_r = 252.23
Triclinic, $[P \overline 1]$
a = 4.8531 (7) Å
b = 11.015 (2) Å
c = 11.787 (2) Å
α = 69.59 (1)°
β = 78.77 (1)°
γ = 83.62 (2)°
V = 578.59 (17) Å³
Z = 2
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 293 K
0.40 × 0.22 × 0.12 mm

Data collection

Oxford Diffraction Xcalibur diffractometer with a Sapphire CCD detector
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ) T_min = 0.955, T_max = 0.986
3557 measured reflections
2314 independent reflections
1900 reflections with I > 2σ(I)
R_int = 0.011

Refinement

R[F² > 2σ(F²)] = 0.046
wR(F²) = 0.119
S = 1.05
2314 reflections
170 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O5	0.84 (2)	2.11 (2)	2.648 (2)	121 (2)
N1—H1N⋯O1ⁱ	0.84 (2)	2.34 (2)	3.072 (2)	146 (2)
O3—H3O⋯O2ⁱⁱ	0.83 (2)	1.86 (2)	2.688 (2)	176 (3)
Symmetry codes: (i) x+1, y, z; (ii) -x-1, -y, -z+2.

Data collection: CrysAlis CCD (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812007258/kp2388sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812007258/kp2388Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812007258/kp2388Isup3.cml

checkCIF report

Comment top

As part of our studies on the substituent effects on the structures and other aspects of N-(aryl)-amides (Gowda et al., 1999, 2006; Chaithanya et al., 2012), N-(aryl)-methanesulfonamides (Gowda et al., 2007), N-chloroarylsulfonamides (Jyothi & Gowda, 2004) and N-bromoarylsulfonamides (Usha & Gowda, 2006), in the present work, the crystal structure of N-(2-nitro-4-methylphenyl)succinamic acid has been determined (Fig. 1). The conformation of the N—H bond in the amide segment is syn to the ortho–nitro group in the benzene ring, similar to that observed between the N—H bond and the ortho–chloro atom in N-(2-chloro-4-methylphenyl)- succinamic acid (I) (Chaithanya et al., 2012).

Further, the conformations of the amide oxygen and the carboxyl oxygen of the acid segment are syn to each other, in contrast to the anti conformation observed in (I). But both the amide oxygen and the carboxyl oxygen are anti to the H atoms on the adjacent –CH₂ group, in both the compounds.

The dihedral angle between the phenyl ring and the amide group is 36.1 (1)°, compared to the value of 48.4 (1)° in (I). The amide H-atom shows bifurcated intramolecular H-bonding with the O-atom of the ortho-nitro group and the intermolecular H-bonding with the carbonyl oxygen atom of the other molecule. In the crystal, the molecules are packed into chains through intermolecular N—H···O(C) along the direction [100] and pairs of centrosymmetric O–H···O(C) hydrogen bonds (Table 1, Fig. 2).

Related literature top

For our studies on the effects of substituents on the structures and other aspects of N-(aryl)-amides, see: Gowda et al. (1999, 2006); Chaithanya et al. (2012). For N-(aryl)-methanesulfonamides, see: Gowda et al. (2007). For N-chloroarylamides, see: Jyothi & Gowda (2004). For N-bromoarylsulfonamides, see: Usha & Gowda (2006).

Experimental top

The solution of succinic anhydride (0.01 mol) in toluene (25 mL) was treated dropwise with the solution of 2-nitro,4-methylaniline (0.01 mol) also in toluene (20 mL) with constant stirring. The resulting mixture was stirred for about one h and set aside for an additional h at room temperature for completion of the reaction. The mixture was then treated with dilute hydrochloric acid to remove the unreacted 2-nitro-4-methyl- aniline. The resultant title compound was filtered under suction and washed thoroughly with water to remove the unreacted succinic anhydride and succinic acid. Repeated recrystallisations from ethanol were applied until the constant melting point. The purity of the compound was checked and characterised by its infrared and NMR spectra.

Needle like yellow single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation of the solvent at room temperature.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2009); cell refinement: CrysAlis RED (Oxford Diffraction, 2009); data reduction: CrysAlis RED (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Molecular structure of the title compound showing the atom labelling scheme and intramolecular N-H···O hydrogen bond. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Molecular packing of the title compound with hydrogen bonding shown as dashed lines.

N-(4-Methyl-2-nitrophenyl)succinamic acid top

Crystal data top

C₁₁H₁₂N₂O₅	Z = 2
M_r = 252.23	F(000) = 264
Triclinic, P1	D_x = 1.448 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 4.8531 (7) Å	Cell parameters from 1681 reflections
b = 11.015 (2) Å	θ = 3.1–27.8°
c = 11.787 (2) Å	µ = 0.12 mm⁻¹
α = 69.59 (1)°	T = 293 K
β = 78.77 (1)°	Needle, yellow
γ = 83.62 (2)°	0.40 × 0.22 × 0.12 mm
V = 578.59 (17) Å³

Data collection top

Oxford Diffraction Xcalibur diffractometer with a Sapphire CCD detector	2314 independent reflections
Radiation source: fine-focus sealed tube	1900 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.011
Rotation method data acquisition using ω and phi scans	θ_max = 26.4°, θ_min = 3.1°
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2009)	h = −5→6
T_min = 0.955, T_max = 0.986	k = −13→13
3557 measured reflections	l = −14→14

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.119	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.0471P)² + 0.2987P] where P = (F_o² + 2F_c²)/3
2314 reflections	(Δ/σ)_max = 0.006
170 parameters	Δρ_max = 0.23 e Å⁻³
2 restraints	Δρ_min = −0.22 e Å⁻³

Crystal data top

C₁₁H₁₂N₂O₅	γ = 83.62 (2)°
M_r = 252.23	V = 578.59 (17) Å³
Triclinic, P1	Z = 2
a = 4.8531 (7) Å	Mo Kα radiation
b = 11.015 (2) Å	µ = 0.12 mm⁻¹
c = 11.787 (2) Å	T = 293 K
α = 69.59 (1)°	0.40 × 0.22 × 0.12 mm
β = 78.77 (1)°

Data collection top

Oxford Diffraction Xcalibur diffractometer with a Sapphire CCD detector	2314 independent reflections
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2009)	1900 reflections with I > 2σ(I)
T_min = 0.955, T_max = 0.986	R_int = 0.011
3557 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.046	2 restraints
wR(F²) = 0.119	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.23 e Å⁻³
2314 reflections	Δρ_min = −0.22 e Å⁻³
170 parameters

Special details top

Experimental. CrysAlis RED (Oxford Diffraction, 2009) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

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 (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.0723 (3)	0.37100 (17)	0.38806 (15)	0.0344 (4)
C2	0.2308 (4)	0.40404 (17)	0.26912 (16)	0.0351 (4)
C3	0.1566 (4)	0.51144 (18)	0.17381 (17)	0.0423 (4)
H3	0.2650	0.5299	0.0960	0.051*
C4	−0.0749 (4)	0.59120 (18)	0.19244 (18)	0.0439 (5)
C5	−0.2278 (4)	0.56114 (19)	0.31041 (19)	0.0463 (5)
H5	−0.3823	0.6146	0.3257	0.056*
C6	−0.1571 (4)	0.45416 (19)	0.40568 (17)	0.0429 (4)
H6	−0.2652	0.4373	0.4834	0.052*
C7	−0.0488 (4)	0.18197 (18)	0.57398 (16)	0.0385 (4)
C8	0.0872 (4)	0.0644 (2)	0.65902 (18)	0.0474 (5)
H8A	0.1761	0.0914	0.7127	0.057*
H8B	0.2330	0.0268	0.6106	0.057*
C9	−0.1198 (4)	−0.03824 (19)	0.73683 (18)	0.0459 (5)
H9A	−0.2447	−0.0471	0.6855	0.055*
H9B	−0.0163	−0.1206	0.7655	0.055*
C10	−0.2937 (4)	−0.01095 (18)	0.84541 (16)	0.0392 (4)
C11	−0.1609 (5)	0.7055 (2)	0.0885 (2)	0.0627 (6)
H11A	−0.3126	0.6828	0.0593	0.075*
H11B	−0.0037	0.7291	0.0228	0.075*
H11C	−0.2211	0.7774	0.1169	0.075*
N1	0.1378 (3)	0.26122 (16)	0.48575 (14)	0.0402 (4)
H1N	0.308 (3)	0.237 (2)	0.485 (2)	0.048*
N2	0.4831 (3)	0.32707 (15)	0.23859 (14)	0.0422 (4)
O1	−0.3032 (3)	0.20209 (15)	0.58421 (14)	0.0599 (5)
O2	−0.2182 (3)	0.05642 (16)	0.89554 (14)	0.0591 (4)
O3	−0.5284 (3)	−0.07162 (16)	0.88538 (13)	0.0533 (4)
H3O	−0.606 (5)	−0.063 (3)	0.9514 (18)	0.064*
O4	0.5972 (4)	0.35547 (18)	0.13202 (15)	0.0802 (6)
O5	0.5750 (3)	0.23852 (15)	0.31947 (14)	0.0579 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0299 (8)	0.0388 (9)	0.0306 (8)	−0.0020 (7)	−0.0043 (7)	−0.0073 (7)
C2	0.0333 (9)	0.0362 (9)	0.0355 (9)	−0.0031 (7)	−0.0022 (7)	−0.0129 (7)
C3	0.0483 (11)	0.0408 (10)	0.0327 (9)	−0.0069 (8)	−0.0023 (8)	−0.0070 (8)
C4	0.0483 (11)	0.0377 (10)	0.0411 (10)	−0.0042 (8)	−0.0115 (8)	−0.0048 (8)
C5	0.0402 (10)	0.0427 (10)	0.0497 (11)	0.0075 (8)	−0.0062 (9)	−0.0114 (9)
C6	0.0361 (10)	0.0485 (11)	0.0363 (9)	0.0034 (8)	0.0006 (8)	−0.0096 (8)
C7	0.0297 (9)	0.0478 (10)	0.0306 (8)	0.0016 (7)	−0.0045 (7)	−0.0053 (8)
C8	0.0317 (9)	0.0548 (12)	0.0379 (10)	0.0051 (8)	−0.0017 (7)	0.0021 (9)
C9	0.0420 (10)	0.0419 (10)	0.0411 (10)	0.0059 (8)	−0.0029 (8)	−0.0026 (8)
C10	0.0329 (9)	0.0389 (9)	0.0347 (9)	0.0001 (7)	−0.0070 (7)	0.0016 (8)
C11	0.0699 (15)	0.0489 (12)	0.0536 (13)	0.0014 (11)	−0.0153 (11)	0.0036 (10)
N1	0.0255 (7)	0.0483 (9)	0.0344 (8)	0.0038 (6)	−0.0019 (6)	−0.0017 (7)
N2	0.0416 (9)	0.0422 (9)	0.0398 (8)	−0.0020 (7)	0.0036 (7)	−0.0154 (7)
O1	0.0268 (7)	0.0661 (10)	0.0599 (9)	0.0007 (6)	−0.0064 (6)	0.0112 (7)
O2	0.0535 (9)	0.0721 (10)	0.0508 (9)	−0.0233 (8)	0.0059 (7)	−0.0212 (8)
O3	0.0425 (8)	0.0697 (10)	0.0441 (8)	−0.0172 (7)	0.0014 (6)	−0.0150 (7)
O4	0.0901 (13)	0.0767 (12)	0.0462 (9)	0.0173 (10)	0.0240 (9)	−0.0119 (8)
O5	0.0500 (8)	0.0649 (10)	0.0499 (8)	0.0201 (7)	−0.0043 (7)	−0.0172 (8)

Geometric parameters (Å, º) top

C1—C6	1.392 (2)	C8—C9	1.516 (3)
C1—N1	1.405 (2)	C8—H8A	0.9700
C1—C2	1.406 (2)	C8—H8B	0.9700
C2—C3	1.388 (2)	C9—C10	1.494 (3)
C2—N2	1.469 (2)	C9—H9A	0.9700
C3—C4	1.379 (3)	C9—H9B	0.9700
C3—H3	0.9300	C10—O2	1.219 (2)
C4—C5	1.388 (3)	C10—O3	1.306 (2)
C4—C11	1.506 (3)	C11—H11A	0.9600
C5—C6	1.380 (3)	C11—H11B	0.9600
C5—H5	0.9300	C11—H11C	0.9600
C6—H6	0.9300	N1—H1N	0.840 (15)
C7—O1	1.220 (2)	N2—O4	1.215 (2)
C7—N1	1.356 (2)	N2—O5	1.216 (2)
C7—C8	1.510 (2)	O3—H3O	0.828 (17)

C6—C1—N1	120.65 (16)	C9—C8—H8B	109.0
C6—C1—C2	116.32 (16)	H8A—C8—H8B	107.8
N1—C1—C2	123.04 (16)	C10—C9—C8	114.65 (18)
C3—C2—C1	121.65 (16)	C10—C9—H9A	108.6
C3—C2—N2	116.31 (15)	C8—C9—H9A	108.6
C1—C2—N2	122.05 (15)	C10—C9—H9B	108.6
C4—C3—C2	121.19 (17)	C8—C9—H9B	108.6
C4—C3—H3	119.4	H9A—C9—H9B	107.6
C2—C3—H3	119.4	O2—C10—O3	123.11 (18)
C3—C4—C5	117.44 (17)	O2—C10—C9	123.32 (17)
C3—C4—C11	121.31 (19)	O3—C10—C9	113.48 (18)
C5—C4—C11	121.24 (19)	C4—C11—H11A	109.5
C6—C5—C4	121.87 (18)	C4—C11—H11B	109.5
C6—C5—H5	119.1	H11A—C11—H11B	109.5
C4—C5—H5	119.1	C4—C11—H11C	109.5
C5—C6—C1	121.50 (17)	H11A—C11—H11C	109.5
C5—C6—H6	119.3	H11B—C11—H11C	109.5
C1—C6—H6	119.3	C7—N1—C1	126.29 (15)
O1—C7—N1	123.78 (16)	C7—N1—H1N	116.4 (15)
O1—C7—C8	122.49 (16)	C1—N1—H1N	116.8 (15)
N1—C7—C8	113.73 (15)	O4—N2—O5	121.64 (17)
C7—C8—C9	113.01 (16)	O4—N2—C2	118.41 (17)
C7—C8—H8A	109.0	O5—N2—C2	119.95 (15)
C9—C8—H8A	109.0	C10—O3—H3O	110.5 (18)
C7—C8—H8B	109.0

C6—C1—C2—C3	−2.0 (3)	O1—C7—C8—C9	13.1 (3)
N1—C1—C2—C3	178.40 (17)	N1—C7—C8—C9	−166.36 (18)
C6—C1—C2—N2	178.13 (16)	C7—C8—C9—C10	−79.0 (2)
N1—C1—C2—N2	−1.5 (3)	C8—C9—C10—O2	−25.8 (3)
C1—C2—C3—C4	0.7 (3)	C8—C9—C10—O3	157.49 (16)
N2—C2—C3—C4	−179.39 (17)	O1—C7—N1—C1	−5.4 (3)
C2—C3—C4—C5	1.0 (3)	C8—C7—N1—C1	174.13 (18)
C2—C3—C4—C11	−178.18 (19)	C6—C1—N1—C7	39.0 (3)
C3—C4—C5—C6	−1.4 (3)	C2—C1—N1—C7	−141.4 (2)
C11—C4—C5—C6	177.7 (2)	C3—C2—N2—O4	−5.4 (3)
C4—C5—C6—C1	0.1 (3)	C1—C2—N2—O4	174.42 (19)
N1—C1—C6—C5	−178.82 (18)	C3—C2—N2—O5	173.52 (17)
C2—C1—C6—C5	1.6 (3)	C1—C2—N2—O5	−6.6 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O5	0.84 (2)	2.11 (2)	2.648 (2)	121 (2)
N1—H1N···O1ⁱ	0.84 (2)	2.34 (2)	3.072 (2)	146 (2)
O3—H3O···O2ⁱⁱ	0.83 (2)	1.86 (2)	2.688 (2)	176 (3)

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

Experimental details

Crystal data
Chemical formula	C₁₁H₁₂N₂O₅
M_r	252.23
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	4.8531 (7), 11.015 (2), 11.787 (2)
α, β, γ (°)	69.59 (1), 78.77 (1), 83.62 (2)
V (Å³)	578.59 (17)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.40 × 0.22 × 0.12

Data collection
Diffractometer	Oxford Diffraction Xcalibur diffractometer with a Sapphire CCD detector
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2009)
T_min, T_max	0.955, 0.986
No. of measured, independent and observed [I > 2σ(I)] reflections	3557, 2314, 1900
R_int	0.011
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.119, 1.05
No. of reflections	2314
No. of parameters	170
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.23, −0.22

Computer programs: CrysAlis CCD (Oxford Diffraction, 2009), CrysAlis RED (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O5	0.840 (15)	2.11 (2)	2.648 (2)	121.2 (18)
N1—H1N···O1ⁱ	0.840 (15)	2.338 (18)	3.072 (2)	146 (2)
O3—H3O···O2ⁱⁱ	0.828 (17)	1.862 (17)	2.688 (2)	176 (3)

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

Acknowledgements

BTG thanks the University Grants Commission, Government of India, New Delhi, for a UGC-BSR one-time grant to faculty.

References

Chaithanya, U., Foro, S. & Gowda, B. T. (2012). Acta Cryst. E68, o785. CSD CrossRef IUCr Journals Google Scholar
Gowda, B. T., Bhat, D. K., Fuess, H. & Weiss, A. (1999). Z. Naturforsch. Teil A, 54, 261–267. CAS Google Scholar
Gowda, B. T., Foro, S. & Fuess, H. (2007). Acta Cryst. E63, o2570. Web of Science CSD CrossRef IUCr Journals Google Scholar
Gowda, B. T., Kozisek, J. & Fuess, H. (2006). Z. Naturforsch. Teil A, 61, 588–594. CAS Google Scholar
Jyothi, K. & Gowda, B. T. (2004). Z. Naturforsch. Teil A, 59, 64–68. CAS Google Scholar
Oxford Diffraction (2009). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Usha, K. M. & Gowda, B. T. (2006). J. Chem. Sci. 118, 351–359. Web of Science CrossRef CAS Google Scholar