Experimental charge density and electrostatic potential of glycyl-L-threonine dihydrate

The experimental electron density distribution in glycyl-L-threonine dihydrate has been investigated using single-crystal X-ray diffraction data at 110 K to a resolution of (sin θ/λ) = 1.2 Å⁻¹. Multipolar pseudo-atom refinement was carried out against 5417 observed data and the molecular electron density was analyzed using topological methods. The experimental electrostatic potential around the molecule is discussed in terms of molecular interactions. Crystal data: C₆H₁₂N₂O₄.2H₂O, M_r = 212.2, orthorhombic, P2₁2₁2₁, Z = 4, F(000) = 456 e, T = 110 K, a = 9.572 (3), b = 10.039 (3), c = 10.548 (2) Å, V = 1013.6 (4) ų, D_x = 1.3 g cm⁻³, µ = 1.2 cm⁻¹ for λ_Mo = 0.7107 Å.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software (Enraf-Nonius, 1989); data reduction: DREAR (Blessing, 1987, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: MOLLY (Hansen & Coppens, 1978); molecular graphics: ORTEP (Johnson, 1970).

Glycyl-L-Threonine Dihydrate

Crystal data

C6H12N2O4·2(H2O)	Dx = 1.390 Mg m^−3
Mr = 212.21	Mo Kα radiation, λ = 0.71068 Å
Orthorhombic, P212121	Cell parameters from 25 reflections
a = 9.572 (3) Å	θ = 11–20°
b = 10.039 (3) Å	µ = 0.12 mm^−1
c = 10.548 (3) Å	T = 110 K
V = 1013.7 (5) Å^3	Rectangular prism, colorless
Z = 4	0.30 × 0.30 × 0.15 mm
F(000) = 456

Data collection

ENRAF-NONIUS CAD4 diffractometer	Rint = 0.023
Radiation source: fine-focus sealed tube	θmax = 54.9°, θmin = 2.8°
Graphite monochromator	h = −22→22
ω/2θ scans	k = −23→23
15903 measured reflections	l = 0→24
5417 independent reflections	4 standard reflections every 120 min
3978 reflections with I > 3σ(I)	intensity decay: 3%

Refinement

Refinement on F	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.025	Only H-atom displacement parameters refined
3978 reflections	w = 1/[σ^2(Fo^2)]
405 parameters	(Δ/σ)max = 0.05
0 restraints	Δρmax = 0.10 e Å^−3
Primary atom site location: structure-invariant direct methods	Δρmin = −0.10 e Å^−3

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

	x	y	z	Uiso*/Ueq
C1A	0.11292 (5)	−0.38015 (5)	0.53973 (5)	0.0123 (2)
C1	0.17857 (5)	−0.24934 (5)	0.49970 (4)	0.0098 (2)
C2A	0.13187 (5)	−0.04093 (5)	0.38561 (4)	0.0105 (2)
C2B	0.11723 (6)	−0.04410 (6)	0.24045 (5)	0.0140 (2)
C2G	0.21530 (7)	−0.14443 (7)	0.18052 (6)	0.0240 (3)
C2	0.04583 (5)	0.07540 (5)	0.43915 (5)	0.0107 (2)
O1	0.30234 (4)	−0.22458 (4)	0.52137 (4)	0.0153 (2)
O2G	−0.02571 (4)	−0.07192 (4)	0.21065 (4)	0.0149 (2)
O21	−0.05779 (4)	0.04844 (4)	0.50909 (3)	0.0135 (2)
O22	0.08373 (4)	0.18971 (4)	0.40860 (4)	0.0167 (2)
N1	0.20802 (5)	−0.45253 (4)	0.62489 (4)	0.0124 (2)
N2	0.09031 (4)	−0.16725 (4)	0.43985 (4)	0.0112 (2)
OW1	−0.16550 (4)	0.23049 (4)	0.67630 (4)	0.0166 (2)
OW2	0.04059 (6)	0.39211 (5)	0.76544 (5)	0.0338 (4)
HN11	0.29923	−0.48326	0.58126	0.017 (3)*
HN12	0.14652	−0.51721	0.67651	0.019 (3)*
HN13	0.23880	−0.39164	0.69861	0.017 (3)*
H2A	0.23901	−0.01902	0.41133	0.015 (2)*
H2G1	0.19334	−0.24265	0.22270	0.033 (3)*
H2G2	0.32464	−0.12909	0.20171	0.033 (3)*
H2G3	0.19853	−0.13968	0.07895	0.033 (3)*
H1A1	0.09721	−0.44392	0.45777	0.016 (2)*
H1A2	0.01796	−0.34659	0.58629	0.017 (2)*
HN2	−0.01183	−0.19992	0.44081	0.015 (2)*
H2B	0.14321	0.05730	0.21284	0.019 (3)*
H2G	−0.04333	−0.15493	0.16731	0.016 (3)*
HW11	−0.12677	0.18846	0.60235	0.023 (2)*
HW12	−0.24300	0.27697	0.63945	0.028 (2)*
HW21	−0.03766	0.34145	0.73715	0.041 (3)*
HW22	0.02516	0.43039	0.84732	0.033 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1A	0.0102 (2)	0.0104 (2)	0.0163 (3)	−0.0014 (1)	−0.0026 (2)	0.0020 (2)
C1	0.0079 (2)	0.0099 (1)	0.0116 (2)	0.0002 (2)	−0.0004 (1)	0.0009 (1)
C2A	0.0088 (2)	0.0103 (2)	0.0123 (2)	−0.0006 (2)	0.0000 (2)	0.0012 (2)
C2B	0.0153 (2)	0.0151 (2)	0.0116 (2)	−0.0029 (2)	0.0019 (2)	0.0007 (2)
C2G	0.0178 (3)	0.0326 (4)	0.0216 (3)	0.0010 (3)	0.0066 (3)	−0.0082 (3)
C2	0.0093 (2)	0.0097 (2)	0.0131 (2)	−0.0004 (1)	−0.0012 (2)	0.0008 (1)
O1	0.0088 (2)	0.0149 (2)	0.0223 (3)	−0.0016 (2)	−0.0025 (2)	0.0055 (2)
O2G	0.0157 (2)	0.0144 (2)	0.0147 (2)	0.0011 (2)	−0.0030 (2)	−0.0019 (2)
O21	0.0115 (1)	0.0136 (2)	0.0155 (2)	−0.0002 (1)	0.0024 (2)	−0.0008 (1)
O22	0.0145 (2)	0.0095 (2)	0.0260 (2)	−0.0004 (2)	0.0009 (3)	0.0040 (2)
N1	0.0112 (2)	0.0119 (2)	0.0143 (2)	0.0001 (2)	−0.0011 (2)	0.0028 (2)
N2	0.0083 (2)	0.0099 (2)	0.0153 (2)	0.0001 (2)	−0.0010 (2)	0.0027 (2)
OW1	0.0157 (2)	0.0179 (2)	0.0162 (2)	0.0026 (2)	0.0003 (2)	−0.0023 (2)
OW2	0.0422 (4)	0.0389 (4)	0.0202 (3)	−0.0268 (4)	0.0134 (3)	−0.0091 (3)

Geometric parameters (Å, º)

C1A—N1	1.4709 (6)	C2A—C2B	1.5381 (7)
C1A—C1	1.5159 (7)	C2B—O2G	1.4314 (6)
C1—O1	1.2319 (6)	C2B—C2G	1.5151 (8)
C1—N2	1.3385 (6)	C2—O22	1.2459 (6)
C2A—N2	1.4470 (6)	C2—O21	1.2655 (6)
C2A—C2	1.5366 (7)
N1—C1A—C1	109.97 (4)	O2G—C2B—C2G	111.77 (4)
O1—C1—N2	124.77 (4)	O2G—C2B—C2A	108.05 (4)
O1—C1—C1A	121.46 (4)	C2G—C2B—C2A	111.89 (5)
N2—C1—C1A	113.78 (4)	O22—C2—O21	125.17 (5)
N2—C2A—C2	111.92 (4)	O22—C2—C2A	116.67 (4)
N2—C2A—C2B	110.52 (4)	O21—C2—C2A	118.15 (4)
C2—C2A—C2B	109.44 (4)	C1—N2—C2A	123.55 (4)
N1—C1A—C1—O1	11.01 (6)	C2B—C2A—C2—O22	−64.61 (6)
N1—C1A—C1—N2	−169.30 (4)	N2—C2A—C2—O21	−8.15 (6)
N2—C2A—C2B—O2G	59.23 (5)	C2B—C2A—C2—O21	114.72 (5)
C2—C2A—C2B—O2G	−64.45 (4)	O1—C1—N2—C2A	3.95 (9)
N2—C2A—C2B—C2G	−64.23 (5)	C1A—C1—N2—C2A	−175.72 (5)
C2—C2A—C2B—C2G	172.08 (4)	C2—C2A—N2—C1	−123.48 (5)
N2—C2A—C2—O22	172.52 (4)	C2B—C2A—N2—C1	114.26 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—HN11···O21^i	1.0338 (7)	1.7915 (4)	2.8195 (6)	172.20 (3)
N1—HN12···OW2^ii	1.0321 (6)	1.6544 (5)	2.6832 (6)	174.39 (3)
N1—HN13···OW1^iii	1.0325 (7)	1.9331 (4)	2.8178 (6)	141.85 (3)
N2—HN2···O1^iv	1.0312 (6)	1.9742 (3)	2.9907 (5)	168.03 (2)
O2G—H2G···O22^v	0.9662 (8)	1.7954 (4)	2.7600 (5)	177.17 (4)
OW1—HW11···O21	0.9591 (7)	1.8384 (4)	2.7413 (5)	155.29 (3)
OW1—HW12···O22^vi	0.9613 (7)	1.7662 (4)	2.6843 (6)	159.25 (2)
OW2—HW21···OW1	0.9537 (8)	1.7749 (4)	2.7219 (7)	171.79 (4)
OW2—HW22···O21^vii	0.9568 (8)	1.9489 (4)	2.8544 (6)	157.09 (3)

Symmetry codes: (i) x+1/2, −y−1/2, −z+1; (ii) x, y−1, z; (iii) −x, y−1/2, −z+3/2; (iv) x−1/2, −y−1/2, −z+1; (v) −x, y−1/2, −z+1/2; (vi) x−1/2, −y+1/2, −z+1; (vii) −x, y+1/2, −z+3/2.