Terephthalate salts: salts of monopositive cations

The crystal structures of dilithium, disodium and diammonium terephthalate (1,4-benzenedicarboxylate) have been solved ab initio using Monte Carlo simulated annealing techniques, and refined using synchrotron powder data. The structures of dipotassium terephthalate, potassium hydrogen terephthalate and ammonium hydrogen terephthalate have been refined using single-crystal techniques. Li₂C₈H₄O₄ crystallizes in P2₁/­c, with a = 8.35921 (5), b = 5.13208 (2), c = 8.48490 (5) Å, β = 93.1552 (4)°, V = 363.451 (3) ų, Z = 2. The Li anions are tetrahedrally coordinated and the packing of the terephthalate anions resembles the γ-packing of aromatic hydrocarbons. Na₂C₈H₄O₄ crystallizes in Pbc2₁, with a = 3.54804 (5), b = 10.81604 (16), c = 18.99430 (20) Å, V = 728.92 (2) ų, Z = 4. The coordination of the two independent Na is trigonal prismatic and the terephthalate packing resembles the β packing of hydrocarbons. (NH₄)₂C₈H₄O₄ also crystallizes in Pbc2₁, with a = 4.0053 (5), b = 11.8136 (21), c = 20.1857 (24) Å, V = 955.1 (2) ų, Z = 4. The cations and planar anions are linked by hydrogen bonds and the packing is a looser version of the β packing. K₂C₈H₄O₂ crystallizes in P2₁/­c, with a = 10.561 (4), b = 3.9440 (12), c = 11.535 (5) Å, β = 113.08 (3)°, V = 442.0 (3) ų, Z = 2. The K is trigonal prismatic and the packing is also β. Both KHC₈H₄O₄ and (NH₄)HC₈H₄O₄ crystallize in C2/c, with a = 18.825 (4) and 18.924 (4), b = 3.770 (2) and 3.7967 (9), c = 11.179 (2) and 11.481 (2) Å, β = 98.04 (3) and 94.56 (5)°, V = 816.8 (3) and 790.9 (3) ų, respectively, and Z = 4. The packing in the hydrogen-bonded acid salts is also β. Electrostatic interactions among the terephthalate anions appear to be important in determining the crystal packing.

Computing details

Data collection: P3 for K2tph. Cell refinement: P3 for K2tph. Data reduction: XTAPE for K2tph. Program(s) used to solve structure: SHELXS97 (Sheldrick, 1990) for K2tph, Ktph, ammHtph. Program(s) used to refine structure: GSAS for Li2tph, Na2tph01, amm2tph; SHELXL97 (Sheldrick, 1997) for K2tph, Ktph, ammHtph.

Figures

(Li2tph)

Crystal data

C8H4Li2O4	β = 93.1555 (4)°
Mr = ?	V = ? Å^3
Monoclinic, P21/c	Z = 4
a = 8.35918 (5) Å	? radiation, λ = 1.149681 Å
b = 5.13212 (3) Å	?, ? × ? × ? mm
c = 8.48489 (5) Å

Data collection

2θmin = 7.005°, 2θmax = 56.835°, 2θstep = 0.005°

Refinement

Rp = 0.076	9967 data points
Rwp = 0.098	44 parameters
Rexp = 0.070	8 restraints
χ^2 = 2.016	(Δ/σ)max = 0.07

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
H5	0.1224 (4)	0.2834 (5)	−0.1794 (3)	0.05*	.5
C1	−0.15701 (9)	0.0493 (5)	0.0440 (3)	0.0246 (8)*	.5
C2	−0.07238	−0.16774	0.10623	0.0246 (8)*	.5
C3	0.08463	−0.21708	0.06227	0.0246 (8)*	.5
H2	−0.1223	−0.2834	0.17948	0.05*	.5
H3	0.1430	−0.3668	0.10521	0.05*	.5
C7	−0.3181 (3)	0.1142 (6)	0.1018 (4)	0.0339 (7)*
O8	−0.3862 (2)	−0.0445 (4)	0.1902 (3)	0.0339 (7)*
O9	−0.3809 (3)	0.3274 (4)	0.0532 (3)	0.0339 (7)*
Li	0.4878 (8)	0.1136 (13)	0.3556 (8)	0.035 (2)*

(Na2tph01)

Crystal data

C8H4Na2O4	c = 18.9943 (2) Å
Mr = ?	V = ? Å^3
Orthorhombic, Pbc21	Z = 4
a = 3.54807 (5) Å	? radiation, λ = 1.149681 Å
b = 10.81599 (16) Å	× × mm

Data collection

h = ?→?	l = ?→?
k = ?→?

Refinement

S = 2.60	16 restraints
53 parameters	(Δ/σ)max = 0.10

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

	x	y	z	Uiso*/Ueq
C1	−0.147 (4)	−0.0979 (19)	−0.0964 (18)	0.049 (3)*
C2	−0.334	−0.0092	−0.0548	0.049 (3)*
C3	−0.434	−0.0373	0.0152	0.049 (3)*
C4	−0.346	−0.1541	0.0437	0.049 (3)*
C5	−0.159	−0.2429	0.0021	0.049 (3)*
C6	−0.059	−0.2148	−0.0679	0.049 (3)*
H2	−0.394	0.0714	−0.0744	0.04*
H3	−0.563	0.0239	0.0439	0.04*
H5	−0.098	−0.3235	0.0217	0.04*
H6	0.070	−0.2760	−0.0966	0.04*
C7	−0.058 (7)	−0.0783 (19)	−0.1727 (18)	0.0187 (15)*
C8	−0.419 (7)	−0.175 (2)	0.1208 (17)	0.0187*
O1	−0.024 (4)	0.032 (2)	−0.1976 (19)	0.0187*
O2	−0.038 (4)	−0.168 (2)	−0.2133 (19)	0.0187*
O3	−0.484 (4)	−0.286 (2)	0.1426 (19)	0.0187*
O4	−0.503 (5)	−0.083 (2)	0.1574 (18)	0.0187*
Na1	−1.014 (4)	0.571 (3)	0.1772 (3)	0.0226 (13)*
Na2	0.479 (2)	0.319 (3)	0.272530	0.0226 (13)*

(Na2tph02)

Crystal data

C8H4Na2O4	β = 106.437 (7)°
Mr = ?	V = ? Å^3
Monoclinic, C2/c	Z = 4
a = 20.4146 (15) Å	? radiation, λ = 1.149681 Å
b = 3.4910 (2) Å	?, ? × ? × ? mm
c = 10.3282 (8) Å

Data collection

2θmin = 6.005°, 2θmax = 54.995°, 2θstep = 0.005°

Refinement

Rp = 0.149	χ^2 = NOT FOUND
Rwp = 0.200	9799 data points
Rexp = 0.077

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Na	0.0	0.7464	0.25	0.02*
Na2	0.15066	0.1645	0.42589	0.02*
C	0.09305	0.2653	0.10352	0.02*
O1	0.15114	0.3995	0.10203	0.02*
O2	0.05439	0.131	0.98804	0.02*
O3	0.0724	0.2533	0.20763	0.02*
O4	0.21205	0.6646	0.35445	0.02*
H1	0.194	0.612	0.269	0.04*
H2	0.248	0.724	0.362	0.04*
H3	0.022	0.035	0.996	0.04*	.5

(amm2tph)

Crystal data

C8H16N2O4	c = 20.186 (2) Å
Mr = ?	V = ? Å^3
Orthorhombic, Pbc21	Z = 4
a = 4.0053 (5) Å	? radiation, λ = 1.540629 Å
b = 11.814 (2) Å	?, ? × ? × ? mm

Data collection

2θmin = 8.043°, 2θmax = 69.983°, 2θstep = 0.02°

Refinement

Rp = 0.134	3098 data points
Rwp = 0.179	38 parameters
Rexp = 0.066	10 restraints
χ^2 = 7.344	(Δ/σ)max = 0.11

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

	x	y	z	Uiso*/Ueq
C1	−0.157 (5)	−0.0853 (11)	0.0389 (13)	0.043 (6)*
C2	−0.088	−0.1934	0.0152	0.043 (6)*
C3	−0.171	−0.2222	−0.0496	0.043 (6)*
C4	−0.323	−0.1429	−0.0907	0.043 (6)*
C5	−0.392	−0.0348	−0.0670	0.043 (6)*
C6	−0.309	−0.0059	−0.0022	0.043 (6)*
C7	−0.067	−0.0541	0.1089	0.004 (3)*
C8	−0.413	−0.1740	−0.1607	0.004 (3)*
H2	0.017	−0.2481	0.0436	0.06*
H3	−0.123	−0.2968	−0.0659	0.06*
H5	−0.497	0.0199	−0.0953	0.06*
H6	−0.357	0.0686	0.0142	0.06*
O9	−0.070 (5)	−0.1366 (19)	0.15168	0.004 (3)*
O10	0.001 (5)	0.0464 (17)	0.127 (2)	0.004 (3)*
O11	−0.550 (5)	−0.107 (2)	−0.1998 (8)	0.004 (3)*
O12	−0.483 (5)	−0.2860 (16)	−0.168 (2)	0.004 (3)*
N13	0.504 (4)	0.190 (3)	0.178 (2)	0.04*
H13a	0.445	0.2635	0.1747	0.06*
H13b	0.329	0.1462	0.1671	0.06*
H13c	0.674	0.1763	0.1498	0.06*
H13d	0.569	0.1750	0.2195	0.06*
N14	0.933 (6)	0.923 (3)	0.282 (2)	0.04*
H14a	1.084	0.8666	0.2784	0.06*
H14b	0.911	0.9428	0.3246	0.06*
H14c	1.001	0.9827	0.2580	0.06*
H14d	0.735	0.8983	0.2662	0.06*

(K2tph)

Crystal data

C8H4K2O4	F(000) = 244
Mr = 242.31	Dx = 1.821 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.561 (4) Å	Cell parameters from 19 reflections
b = 3.9440 (12) Å	θ = 5.5–11.4°
c = 11.535 (5) Å	µ = 1.05 mm^−1
β = 113.08 (3)°	T = 293 K
V = 442.0 (3) Å^3	Needle, colourless
Z = 2	0.45 × 0.05 × 0.05 mm

Data collection

Scintillation counter diffractometer	Rint = 0.023
Radiation source: fine-focus sealed tube	h = 0→11
Graphite monochromator	k = −4→4
θ–2θ scans	l = −12→11
1130 measured reflections	5 standard reflections every 200 reflections
584 independent reflections	intensity decay: none
497 reflections with I > 2σ(I)

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.061	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0339P)^2 + 0.0595P] where P = (Fo^2 + 2Fc^2)/3
584 reflections	(Δ/σ)max = 0.010
66 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.19 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.

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
K1	0.61068 (6)	0.20395 (14)	0.16167 (5)	0.0268 (2)
O1	0.35218 (18)	0.1856 (5)	0.16464 (16)	0.0290 (5)
O2	0.32648 (19)	0.3005 (5)	−0.03264 (17)	0.0291 (5)
C7	0.2822 (3)	0.2858 (6)	0.0541 (2)	0.0207 (6)
C1	0.1358 (3)	0.3988 (6)	0.0259 (2)	0.0214 (6)
C2	0.0787 (3)	0.3548 (7)	0.1146 (2)	0.0244 (7)
H2A	0.1312	0.2575	0.1921	0.027 (7)*
C6	0.0548 (3)	0.5466 (7)	−0.0895 (2)	0.0255 (7)
H6A	0.0913	0.5789	−0.1502	0.029 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.0284 (4)	0.0280 (4)	0.0273 (4)	0.0002 (3)	0.0146 (3)	−0.0010 (3)
O1	0.0230 (10)	0.0399 (12)	0.0230 (11)	0.0045 (9)	0.0078 (9)	0.0071 (9)
O2	0.0274 (10)	0.0368 (12)	0.0292 (10)	0.0055 (9)	0.0176 (9)	0.0009 (9)
C7	0.0213 (14)	0.0176 (14)	0.0253 (15)	−0.0013 (11)	0.0114 (13)	−0.0028 (11)
C1	0.0226 (14)	0.0210 (14)	0.0215 (14)	−0.0025 (12)	0.0097 (12)	−0.0023 (11)
C2	0.0219 (15)	0.0309 (16)	0.0195 (14)	0.0041 (12)	0.0071 (12)	0.0050 (11)
C6	0.0272 (16)	0.0321 (16)	0.0218 (14)	0.0002 (13)	0.0146 (12)	0.0021 (12)

Geometric parameters (Å, º)

K1—O1^i	2.676 (2)	O1—C7	1.260 (3)
K1—O2^ii	2.693 (2)	O1—K1^iv	2.676 (2)
K1—O2^iii	2.718 (2)	O1—K1^i	2.780 (2)
K1—O1	2.745 (2)	O2—C7	1.261 (3)
K1—O1^iv	2.780 (2)	O2—K1^ii	2.693 (2)
K1—O2	2.984 (2)	O2—K1^iii	2.718 (2)
K1—C7	3.209 (3)	C7—C1	1.517 (4)
K1—C7^iv	3.441 (3)	C7—K1^i	3.441 (3)
K1—K1^iii	3.889 (2)	C1—C2	1.387 (4)
K1—K1^v	3.9440 (12)	C1—C6	1.397 (4)
K1—K1^vi	3.9440 (12)	C2—C6^vii	1.380 (4)
K1—K1^iv	4.1523 (15)	C6—C2^vii	1.380 (4)
O1^i—K1—O2^ii	84.43 (7)	O2^iii—K1—K1^vi	42.95 (4)
O1^i—K1—O2^iii	159.07 (6)	O1—K1—K1^vi	88.49 (4)
O2^ii—K1—O2^iii	93.59 (6)	O1^iv—K1—K1^vi	42.67 (4)
O1^i—K1—O1	82.18 (6)	O2—K1—K1^vi	97.33 (4)
O2^ii—K1—O1	119.20 (6)	C7—K1—K1^vi	95.77 (5)
O2^iii—K1—O1	116.43 (6)	C7^iv—K1—K1^vi	61.36 (5)
O1^i—K1—O1^iv	92.55 (6)	K1^iii—K1—K1^vi	65.57 (2)
O2^ii—K1—O1^iv	159.44 (6)	K1^v—K1—K1^vi	180.0
O2^iii—K1—O1^iv	81.99 (6)	O1^i—K1—K1^iv	85.14 (5)
O1—K1—O1^iv	80.31 (6)	O2^ii—K1—K1^iv	157.54 (4)
O1^i—K1—O2	106.31 (6)	O2^iii—K1—K1^iv	103.09 (5)
O2^ii—K1—O2	83.42 (6)	O1—K1—K1^iv	39.40 (4)
O2^iii—K1—O2	94.11 (6)	O1^iv—K1—K1^iv	40.95 (4)
O1—K1—O2	45.58 (6)	O2—K1—K1^iv	80.51 (5)
O1^iv—K1—O2	116.83 (6)	C7—K1—K1^iv	60.42 (5)
O1^i—K1—C7	92.12 (7)	C7^iv—K1—K1^iv	48.91 (5)
O2^ii—K1—C7	100.17 (7)	K1^iii—K1—K1^iv	91.82 (4)
O2^iii—K1—C7	108.71 (6)	K1^v—K1—K1^iv	118.354 (13)
O1—K1—C7	22.76 (6)	K1^vi—K1—K1^iv	61.646 (13)
O1^iv—K1—C7	100.27 (6)	C7—O1—K1^iv	146.68 (16)
O2—K1—C7	23.13 (6)	C7—O1—K1	99.82 (15)
O1^i—K1—C7^iv	74.33 (7)	K1^iv—O1—K1	99.99 (6)
O2^ii—K1—C7^iv	144.53 (6)	C7—O1—K1^i	111.08 (15)
O2^iii—K1—C7^iv	96.39 (7)	K1^iv—O1—K1^i	92.55 (6)
O1—K1—C7^iv	86.13 (6)	K1—O1—K1^i	97.45 (6)
O1^iv—K1—C7^iv	19.98 (6)	C7—O2—K1^ii	136.08 (16)
O2—K1—C7^iv	129.42 (6)	C7—O2—K1^iii	130.32 (16)
C7—K1—C7^iv	108.55 (6)	K1^ii—O2—K1^iii	93.59 (6)
O1^i—K1—K1^iii	150.25 (5)	C7—O2—K1	88.54 (15)
O2^ii—K1—K1^iii	87.47 (5)	K1^ii—O2—K1	96.58 (6)
O2^iii—K1—K1^iii	49.92 (4)	K1^iii—O2—K1	85.89 (6)
O1—K1—K1^iii	76.95 (5)	O1—C7—O2	124.4 (2)
O1^iv—K1—K1^iii	104.41 (5)	O1—C7—C1	116.9 (2)
O2—K1—K1^iii	44.19 (4)	O2—C7—C1	118.7 (2)
C7—K1—K1^iii	61.23 (5)	O1—C7—K1	57.42 (13)
C7^iv—K1—K1^iii	124.39 (6)	O2—C7—K1	68.34 (14)
O1^i—K1—K1^v	44.77 (5)	C1—C7—K1	165.64 (17)
O2^ii—K1—K1^v	43.46 (4)	O1—C7—K1^i	48.94 (13)
O2^iii—K1—K1^v	137.05 (4)	O2—C7—K1^i	130.44 (17)
O1—K1—K1^v	91.51 (4)	C1—C7—K1^i	89.43 (14)
O1^iv—K1—K1^v	137.33 (4)	K1—C7—K1^i	77.19 (6)
O2—K1—K1^v	82.67 (4)	C2—C1—C6	118.3 (2)
C7—K1—K1^v	84.23 (5)	C2—C1—C7	120.4 (2)
C7^iv—K1—K1^v	118.64 (5)	C6—C1—C7	121.2 (2)
K1^iii—K1—K1^v	114.43 (2)	C6^vii—C2—C1	120.9 (2)
O1^i—K1—K1^vi	135.23 (5)	C2^vii—C6—C1	120.7 (2)
O2^ii—K1—K1^vi	136.54 (4)

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

(Ktph)

Crystal data

C8H5KO4	Z = 4
Mr = 204.22	F(000) = 416
Monoclinic, C2/c	Dx = 1.715 Mg m^−3
a = 18.825 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 3.7700 (8) Å	µ = 0.65 mm^−1
c = 11.179 (2) Å	T = 293 K
β = 94.56 (3)°	Plate, colourless
V = 790.9 (3) Å^3	0.42 × 0.10 × 0.04 mm

Data collection

Radiation source: fine-focus sealed tube	Rint = 0.029
Graphite monochromator	θmax = 20.0°, θmin = 3.7°
695 measured reflections	h = 0→18
376 independent reflections	k = −3→3
296 reflections with I > 2σ(I)	l = −10→10

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.072	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0438P)^2] where P = (Fo^2 + 2Fc^2)/3
376 reflections	(Δ/σ)max = 0.017
72 parameters	Δρmax = 0.15 e Å^−3
1 restraint	Δρmin = −0.15 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.

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	Occ. (<1)
K	0.0000	0.3441 (4)	0.2500	0.0458 (6)
O1	0.08687 (11)	0.1788 (8)	0.6571 (2)	0.0346 (8)
O2	0.06011 (13)	0.0413 (9)	0.4658 (2)	0.0447 (9)
C4	0.10416 (17)	0.1391 (11)	0.5544 (4)	0.0248 (10)
C1	0.17938 (16)	0.1986 (10)	0.5236 (3)	0.0221 (10)
C2	0.20168 (19)	0.1064 (11)	0.4125 (4)	0.0239 (10)
H2	0.1735 (17)	0.013 (9)	0.349 (3)	0.011 (9)*
C6	0.22783 (18)	0.3424 (12)	0.6104 (4)	0.0251 (10)
H6	0.2123 (17)	0.403 (9)	0.683 (3)	0.026 (10)*
H1	0.0168 (17)	0.08 (2)	0.477 (7)	0.04 (3)*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.0524 (9)	0.0419 (9)	0.0465 (9)	0.000	0.0251 (7)	0.000
O1	0.0234 (15)	0.055 (2)	0.0270 (16)	−0.0062 (15)	0.0102 (12)	−0.0048 (15)
O2	0.0135 (16)	0.087 (3)	0.0332 (17)	−0.0107 (16)	0.0024 (15)	−0.0042 (17)
C4	0.016 (2)	0.027 (2)	0.032 (3)	−0.004 (2)	0.001 (2)	0.001 (2)
C1	0.014 (2)	0.021 (2)	0.030 (3)	−0.0034 (19)	−0.005 (2)	0.0007 (19)
C2	0.021 (2)	0.030 (3)	0.020 (2)	−0.005 (2)	−0.0006 (19)	−0.004 (2)
C6	0.024 (2)	0.031 (2)	0.022 (2)	0.003 (2)	0.010 (2)	0.005 (2)

Geometric parameters (Å, º)

K—O1^i	2.694 (3)	O1—K^ii	2.694 (3)
K—O1^ii	2.694 (3)	O1—K^iii	2.812 (3)
K—O1^iii	2.812 (3)	O2—C4	1.293 (4)
K—O1^iv	2.812 (3)	C4—C1	1.500 (5)
K—O2^v	2.823 (3)	C1—C2	1.386 (5)
K—O2	2.823 (3)	C1—C6	1.388 (5)
K—K^vi	3.7700 (8)	C2—C6^viii	1.385 (5)
K—K^vii	3.7700 (8)	C6—C2^viii	1.385 (5)
O1—C4	1.227 (4)
O1^i—K—O1^ii	96.22 (13)	O2—K—K^vi	113.84 (7)
O1^i—K—O1^iii	177.39 (11)	O1^i—K—K^vii	131.89 (6)
O1^ii—K—O1^iii	86.39 (7)	O1^ii—K—K^vii	131.89 (7)
O1^i—K—O1^iv	86.39 (7)	O1^iii—K—K^vii	45.50 (6)
O1^ii—K—O1^iv	177.39 (11)	O1^iv—K—K^vii	45.50 (6)
O1^iii—K—O1^iv	91.00 (12)	O2^v—K—K^vii	66.16 (7)
O1^i—K—O2^v	98.91 (8)	O2—K—K^vii	66.16 (7)
O1^ii—K—O2^v	112.64 (8)	K^vi—K—K^vii	180.0
O1^iii—K—O2^v	80.03 (8)	C4—O1—K^ii	131.0 (2)
O1^iv—K—O2^v	66.82 (8)	C4—O1—K^iii	117.7 (2)
O1^i—K—O2	112.64 (8)	K^ii—O1—K^iii	86.39 (7)
O1^ii—K—O2	98.91 (8)	C4—O2—K	136.7 (3)
O1^iii—K—O2	66.82 (8)	O1—C4—O2	123.3 (3)
O1^iv—K—O2	80.03 (8)	O1—C4—C1	121.5 (3)
O2^v—K—O2	132.31 (15)	O2—C4—C1	115.2 (3)
O1^i—K—K^vi	48.11 (6)	C2—C1—C6	119.7 (3)
O1^ii—K—K^vi	48.11 (7)	C2—C1—C4	121.8 (3)
O1^iii—K—K^vi	134.50 (6)	C6—C1—C4	118.5 (3)
O1^iv—K—K^vi	134.50 (6)	C6^viii—C2—C1	119.6 (4)
O2^v—K—K^vi	113.84 (7)	C2^viii—C6—C1	120.7 (4)

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

(ammHtph)

Crystal data

C8H9NO4	Z = 4
Mr = 183.16	F(000) = 384
Monoclinic, C2/c	Dx = 1.489 Mg m^−3
a = 18.924 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 3.7967 (8) Å	µ = 0.12 mm^−1
c = 11.481 (2) Å	T = 293 K
β = 98.04 (3)°	Plate, colourless
V = 816.8 (3) Å^3	0.3 × 0.2 × 0.05 mm

Data collection

Radiation source: fine-focus sealed tube	Rint = 0.019
Graphite monochromator	θmax = 20.0°, θmin = 3.6°
785 measured reflections	h = −18→18
373 independent reflections	k = −3→3
307 reflections with I > 2σ(I)	l = −11→11

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.076	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0536P)^2] where P = (Fo^2 + 2Fc^2)/3
373 reflections	(Δ/σ)max = 0.243
80 parameters	Δρmax = 0.11 e Å^−3
1 restraint	Δρmin = −0.18 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.

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	Occ. (<1)
O1	0.09478 (9)	0.1447 (5)	0.65460 (15)	0.0429 (7)
O2	0.05923 (10)	0.0337 (6)	0.46591 (16)	0.0454 (7)
C4	0.10757 (14)	0.1194 (7)	0.5524 (2)	0.0307 (8)
C1	0.18055 (13)	0.1862 (6)	0.5232 (2)	0.0246 (8)
C2	0.19949 (14)	0.1088 (7)	0.4134 (2)	0.0287 (8)
C6	0.23173 (14)	0.3281 (7)	0.6095 (2)	0.0295 (8)
H2A	0.1644 (13)	0.004 (6)	0.354 (2)	0.031 (7)*
H6A	0.2178 (12)	0.383 (7)	0.685 (2)	0.037 (7)*
N1	0.5000	0.0908 (14)	0.7500	0.0459 (10)
H1	0.5335 (19)	−0.046 (10)	0.721 (3)	0.080 (12)*
H2	0.475 (2)	0.189 (12)	0.688 (4)	0.106 (17)*
H3	0.021 (2)	0.00 (2)	0.496 (6)	0.050 (18)*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0298 (12)	0.0699 (15)	0.0310 (12)	−0.0041 (10)	0.0114 (8)	−0.0016 (10)
O2	0.0209 (12)	0.0811 (16)	0.0341 (12)	−0.0141 (13)	0.0034 (10)	0.0001 (11)
C4	0.0244 (19)	0.0352 (17)	0.0324 (17)	−0.0015 (13)	0.0038 (15)	0.0018 (14)
C1	0.0197 (17)	0.0289 (15)	0.0250 (15)	−0.0020 (13)	0.0024 (15)	0.0006 (13)
C2	0.0219 (18)	0.0352 (16)	0.0276 (15)	−0.0046 (14)	−0.0015 (14)	−0.0031 (14)
C6	0.029 (2)	0.0373 (18)	0.0231 (16)	0.0007 (14)	0.0065 (15)	0.0002 (14)
N1	0.049 (3)	0.050 (3)	0.042 (3)	0.000	0.020 (3)	0.000

Geometric parameters (Å, º)

O1—C4	1.235 (3)	C1—C6	1.393 (3)
O2—C4	1.294 (3)	C2—C6^i	1.384 (4)
C4—C1	1.488 (3)	C6—C2^i	1.384 (4)
C1—C2	1.390 (3)
O1—C4—O2	122.5 (2)	C2—C1—C4	122.2 (2)
O1—C4—C1	120.8 (2)	C6—C1—C4	118.8 (2)
O2—C4—C1	116.7 (2)	C1—C2—C6^i	120.3 (2)
C2—C1—C6	119.0 (2)	C2^i—C6—C1	120.7 (2)

Symmetry code: (i) −x+1/2, −y+1/2, −z+1.