Charge-density distribution in potassium dihydrogen phosphoglycolate - a comparison of phosphate and phosphonate groups

Analysis of the experimental and theoretical charge-density distribution in potassium dihydrogen phosphoglycolate has been performed. The P-O bonds in the phosphate group are more polarized and the P atom is more positively charged than in phosphonate groups. The P-O bonds belong to a transit closed-shell (or polar covalent) class, while the ester C-O bond is a covalent (or shared-shell) bond. The coordination of potassium exerts a small effect on the phosphate group, whereas more pronounced changes, e.g. concerning the ellipticities of the C-O bonds, may be observed. The profiles of Laplacians and ellipticities give more insight in the polarization of the bonds.

Computing details

Data collection: CrysAlis CCD, Oxford Diffraction Ltd., Version 1.171.33.55 (release 05-01-2010 CrysAlis171 .NET) (compiled Jan 5 2010,16:28:46); cell refinement: CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.33.55 (release 05-01-2010 CrysAlis171 .NET) (compiled Jan 5 2010,16:28:46); data reduction: CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.33.55 (release 05-01-2010 CrysAlis171 .NET) (compiled Jan 5 2010,16:28:46); program(s) used to refine structure: Volkov et al., (2006); molecular graphics: Volkov et al., (2006); software used to prepare material for publication: Volkov et al., (2006).

Figures

(I)

Crystal data

C2H4KO6P	Dx = 2.131 Mg m^−3
Mr = 194.12	Mo Kα radiation, λ = 0.71073 Å
Monoclinic, P21	Cell parameters from 12001 reflections
a = 7.842 (3) Å	θ = 4.8–75.9°
b = 4.577 (3) Å	µ = 1.11 mm^−1
c = 8.560 (3) Å	T = 90 K
β = 100.04 (2)°	Needle, colourless
V = 302.5 (3) Å^3	0.41 × 0.12 × 0.06 mm
Z = 2

Data collection

Xcalibur, Onyx diffractometer	10634 independent reflections
Radiation source: Enhance (Mo) X-ray Source	8150 reflections with > 3σ(I)
Graphite monochromator	Rint = 0.041
Detector resolution: 8.1956 pixels mm^-1	θmax = 75.9°, θmin = 4.8°
ω and π scans	h = −18→21
Absorption correction: analytical CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.33.55 (release 05-01-2010 CrysAlis171 .NET) (compiled Jan 5 2010,16:28:46) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897)	k = −12→9
Tmin = 0.747, Tmax = 0.940	l = −23→20
30943 measured reflections

Refinement

Refinement on F^2	293 parameters
Least-squares matrix: full	1 restraint
R[F^2 > 2σ(F^2)] = 0.022	w2 = 1/[s^2(Fo^2)]
wR(F^2) = 0.037	(Δ/σ)max = 0.001
S = 1.08	Δρmax = 0.38 e Å^−3
6206 reflections	Δρmin = −0.34 e Å^−3

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

	x	y	z	Uiso*/Ueq
K	0.71196 (3)	0.336402	1.03069 (3)	0.009
P	0.129888 (17)	0.38960 (8)	0.238111 (16)	0.006
O(1)	0.44044 (9)	0.65666 (18)	0.63102 (8)	0.012
O(2)	0.39804 (8)	0.30545 (18)	0.80180 (7)	0.011
O(3)	0.18140 (8)	0.49925 (17)	0.41693 (7)	0.009
O(4)	−0.00662 (8)	0.14341 (16)	0.24390 (7)	0.009
O(5)	0.28734 (8)	0.27571 (17)	0.17878 (7)	0.009
O(6)	0.04409 (8)	0.64604 (16)	0.14715 (7)	0.009
C(1)	0.36490 (7)	0.42132 (14)	0.67057 (6)	0.008
C(2)	0.22978 (7)	0.29269 (14)	0.54130 (6)	0.008
H(1)	0.550197	0.709297	0.719255	0.022
H(2)	0.289724	0.08863	0.508754	0.025
H(3)	0.113121	0.221683	0.586602	0.027
H(4)	0.027295	−0.061351	0.213201	0.021

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.00846 (9)	0.00982 (10)	0.00810 (9)	0.00057 (8)	0.00049 (6)	0.00119 (8)
P	0.00657 (4)	0.00505 (4)	0.00575 (4)	0.00036 (3)	−0.00046 (3)	−0.00026 (3)
O(1)	0.01117 (19)	0.0116 (2)	0.01070 (18)	−0.00362 (16)	−0.00244 (16)	0.00287 (15)
O(2)	0.01199 (17)	0.0130 (2)	0.00678 (14)	−0.00164 (16)	−0.00072 (13)	0.00238 (13)
O(3)	0.01217 (18)	0.00746 (15)	0.00621 (14)	0.00098 (14)	−0.00137 (14)	−0.00075 (12)
O(4)	0.00910 (16)	0.00617 (15)	0.01028 (16)	−0.00115 (13)	0.00100 (14)	−0.00047 (13)
O(5)	0.00771 (15)	0.01100 (17)	0.00929 (15)	0.00107 (14)	0.00069 (13)	−0.00150 (14)
O(6)	0.01127 (17)	0.00610 (14)	0.00848 (15)	0.00137 (14)	−0.00102 (14)	0.00079 (12)
C(1)	0.00778 (15)	0.00862 (17)	0.00633 (13)	−0.00039 (12)	0.00026 (12)	0.00045 (11)
C(2)	0.00960 (16)	0.00846 (17)	0.00667 (14)	−0.00066 (12)	0.00029 (12)	−0.00011 (11)
H(1)	0.022449	0.021374	0.018893	−0.004971	−0.005529	0.002465
H(2)	0.029707	0.018422	0.024827	0.005632	0.000607	−0.001794
H(3)	0.019679	0.037932	0.022387	−0.007259	0.004984	0.003886
H(4)	0.024241	0.012207	0.026746	0.000624	0.001847	−0.001678

Geometric parameters (Å, º)

P—O(3)	1.5945 (6)	C(1)—C(2)	1.5116 (7)
P—O(4)	1.5609 (6)	C(2)—H(2)	1.1030 (6)
P—O(5)	1.5076 (6)	C(2)—H(3)	1.1030 (6)
P—O(6)	1.5013 (6)	K—O(2)	2.8701 (6)
O(1)—C(1)	1.3022 (8)	K—O(2)^iii	3.0228 (8)
O(1)—H(1)	1.0690 (6)	K—O(2)^iv	2.8001 (8)
O(2)—C(1)	1.2284 (8)	K—O(4)^v	2.7527 (6)
O(3)—C(2)	1.4249 (8)	K—O(5)^i	3.1312 (8)
O(4)—H(4)	1.0210 (7)	K—O(5)^vi	2.6947 (7)
O(5)—H(1)^i	1.4455 (6)	K—O(6)^v	2.9800 (7)
O(6)—H(4)^ii	1.4685 (7)	K—O(6)^i	2.7842 (7)
O(3)—P—O(4)	104.90 (3)	O(1)—C(1)—C(2)	115.12 (5)
O(3)—P—O(5)	110.30 (3)	O(2)—C(1)—C(2)	120.72 (5)
O(3)—P—O(6)	105.51 (3)	O(3)—C(2)—C(1)	110.48 (5)
O(4)—P—O(5)	111.57 (4)	O(3)—C(2)—H(2)	116.28 (5)
O(4)—P—O(6)	109.45 (3)	O(3)—C(2)—H(3)	109.21 (5)
O(5)—P—O(6)	114.51 (4)	C(1)—C(2)—H(2)	103.86 (4)
C(1)—O(1)—H(1)	110.45 (6)	C(1)—C(2)—H(3)	112.08 (4)
P—O(3)—C(2)	119.89 (5)	H(2)—C(2)—H(3)	104.80 (5)
P—O(4)—H(4)	116.33 (5)	O(1)—H(1)—O(5)^vi	172.03 (5)
P—O(5)—H(1)^i	123.83 (4)	C(2)—H(2)—H(3)	37.60 (3)
P—O(6)—H(4)^ii	125.13 (4)	C(2)—H(3)—H(2)	37.60 (3)
O(1)—C(1)—O(2)	124.17 (6)	O(4)—H(4)—O(6)^vii	168.83 (4)

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