Tetra­kis(guanidinium) butane-1,2,3,4-tetra­carboxyl­ate

McKee, V.; Najafpour, M.M.

doi:10.1107/S1600536807000724

organic compounds

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ISSN: 2056-9890

Volume 63| Part 2| February 2007| Pages o741-o743

https://doi.org/10.1107/S1600536807000724

Tetrakis(guanidinium) butane-1,2,3,4-tetracarboxylate

Vickie McKee ^a ^* and M. Mahdi Najafpour ^b

^aChemistry Department, Loughborough University, Loughborough, Leicestershire LE11 3TU, England, and ^bDorna Institute of Science, No 83 Padadshah, 14 St. Ahwaz, Khozestan, Iran
^*Correspondence e-mail: v.mckee@lboro.ac.uk

(Received 3 January 2007; accepted 7 January 2007; online 17 January 2007)

The title compound, 4CH₆N₃⁺·C₈H₆O₈⁴⁻, forms a hydrogen-bonded network, in which each O atom is an acceptor for three hydrogen bonds and each guadinium H atom contributes to a single hydrogen bond. The complete anion is generated by inversion symmetry.

Comment

Guanidinium ions have long been utilized in modelling Arg–Glu or Arg–Asp side-chain interactions in proteins (see, for example, Melo et al., 1999 ; Fülscher & Mehler, 1988 ; Singh et al., 1987 ). More recently, the same types of interaction have been utilized in host–guest and sensor chemistry (see, for example, Houk et al., 2005 ) and in crystal engineering (see, for example, Holman et al., 2001 ; Burrows et al., 2003 ). In this paper, we report the structure of the title compound, (I), the guanidinium salt of 1,2,3,4-butanetetracarboxylic acid. A search of the Cambridge Structural Database (Version 5.27; Allen, 2002 ; Fletcher et al., 1996 ) showed that, to date, the only other structurally characterized 1,2,3,4-butanetetracarboxylate salt is [NH₄]₄[C₈H₆O₈]·H₂O (Barnes & Barnes, 1996 ).

The structure of (I) is shown in Fig. 1. The anion lies on a centre of symmetry so that the asymmetric unit contains half a [C₈H₆O₈]⁴⁻ anion and two independent [CH₆N₃]⁺ cations. The anion conformation is very similar to that observed in the previously reported ammonium salt (Barnes & Barnes, 1996), having an extended essentially planar C₆ chain. The anions are arranged in parallel stacks perpendicular to b and interact with each other only through hydrogen bonding via the guanidinium cations.

Each carboxylate group is paired with a guanidinium ion to form a conventional R₂²(9) ring (Etter et al., 1990 ). There is also one R₁²(6) ring involving atoms O4, N11 and N12, and one R₂²(7) ring involving atoms N23, O1^vi and O2^vi [symmetry code: (vi) 2 − x, y, $[{1\over 2}]$ − z]. Each O atom accepts further hydrogen bonds from neighbouring guanadinium cations so that there is a total of three hydrogen bonds to each O atom (Figs. 1 and 3, Table 1). Each H atom in the guanidinium ions is involved in a single hydrogen bond. The resulting three-dimensional hydrogen-bonding network contains a number of large rings, but graph-set analysis of these is not particularly helpful in understanding the structure.

Figure 1
A view of the molecular structure of (I)

, with displacement ellipsoids drawn at the 50% probability level (arbitrary spheres for H atoms). Hydrogen bonds are shown as double dashed lines. [Symmetry code: (i) $[{3\over 2}]$ − x, $[{1\over 2}]$ − y, 1 − z.]

Figure 2
A packing diagram for (I)

, viewed perpendicular to b. Guanidinium ions are shown with white bonds and anions with black bonds, and H atoms have been omitted for clarity. The N⋯O contacts for the hydrogen bonds are shown as dashed lines.

Figure 3
Detail of (I)

, showing the hydrogen bonding to one unique half of the anion. H atoms have been omitted for clarity and the N⋯O contacts for the hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) 2 − x, 1 − y, 1 − z; (vi) 2 − x, y, $[{1\over 2}]$ − z; (vii) $[{3\over 2}]$ − x, − $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (viii) − $[{1\over 2}]$ + x, − $[{1\over 2}]$ + y, z; (ix)-1/2, 1 − y, −1z; (x) x, −1 + y, z.]

Experimental

1,2,3,4-Butanetetracarboxylic acid (Merck; 1 mmol, 0.23 g) was added to an aqueous solution (12 ml) of guanidinum carbonate (Merck; 4.1 mmol, 0.74 g). This solution yielded colourless crystals of (I) after 6 d.

Crystal data

4CH₆N₃⁺·C₈H₆O₈⁴⁻
M_r = 470.48
Monoclinic, C 2/c
a = 13.0411 (13) Å
b = 8.9177 (9) Å
c = 18.8692 (19) Å
β = 98.289 (2)°
V = 2171.5 (4) Å³
Z = 4
D_x = 1.439 Mg m⁻³
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 150 (2) K
Plate, colourless
0.35 × 0.15 × 0.05 mm

Data collection

Bruker SMART CCD area-detector diffractometer
ω scans
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ) T_min = 0.876, T_max = 1.00
8107 measured reflections
2136 independent reflections
1741 reflections with I > 2σ(I)
R_int = 0.026
θ_max = 26.0°

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.036
wR(F²) = 0.089
S = 1.11
2136 reflections
181 parameters
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ²(F_o²) + (0.0378P)² + 1.6442P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N11—H11A⋯O4	0.88 (2)	2.17 (2)	2.9591 (19)	150.1 (18)
N11—H11B⋯O3ⁱ	0.87 (2)	2.20 (2)	2.9854 (18)	148.8 (19)
N12—H12A⋯O1ⁱⁱ	0.88 (2)	1.99 (2)	2.8613 (18)	171 (2)
N12—H12B⋯O4	0.89 (2)	2.04 (2)	2.8495 (18)	151.3 (18)
N13—H13A⋯O3ⁱⁱⁱ	0.86 (2)	1.95 (2)	2.8013 (18)	170 (2)
N13—H13B⋯O2ⁱⁱ	0.88 (2)	2.00 (2)	2.8788 (18)	175 (2)
N21—H21A⋯O2^iv	0.85 (2)	2.00 (2)	2.8528 (18)	175 (2)
N21—H21B⋯O3	0.90 (2)	1.97 (2)	2.8712 (18)	177.0 (19)
N22—H22A⋯O4	0.89 (2)	2.02 (2)	2.8955 (19)	169.8 (19)
N22—H22B⋯O1^v	0.89 (2)	2.14 (2)	2.9844 (19)	156.4 (18)
N23—H23A⋯O1^v	0.89 (2)	2.39 (2)	3.170 (2)	147.0 (18)
N23—H23A⋯O2^vi	0.89 (2)	2.52 (2)	3.0010 (18)	114.7 (16)
N23—H23B⋯O1^vi	0.85 (2)	2.38 (2)	3.0632 (19)	138.1 (19)
Symmetry codes: (i) -x+2, -y+1, -z+1; (ii) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) x, y+1, z; (iv) $[x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (v) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (vi) $[-x+2, y, -z+{\script{1\over 2}}]$ .

Carbon-bound H atoms were placed in calculated positions, with C—H = 0.99–1.00 Å, and refined as riding, with U_iso(H) = 1.2U_eq(C). H atoms bonded to N were located in difference maps and their coordinates refined with a common fixed U_iso value. N—H distances are given in Table 1.

Data collection: SMART (Bruker, 1998 ); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2001 ) and ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536807000724/hb2255sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807000724/hb2255Isup2.hkl

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2001); software used to prepare material for publication: SHELXTL.

Tetrakis(guanidinium) butane-1,2,3,4-tetracarboxylate top

Crystal data top

4CH₆N₃⁺·C₈H₆O₈⁴⁻	F(000) = 1000
M_r = 470.48	D_x = 1.439 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 3043 reflections
a = 13.0411 (13) Å	θ = 2.2–23.4°
b = 8.9177 (9) Å	µ = 0.12 mm⁻¹
c = 18.8692 (19) Å	T = 150 K
β = 98.289 (2)°	Plate, colourless
V = 2171.5 (4) Å³	0.35 × 0.15 × 0.05 mm
Z = 4

Data collection top

Bruker SMART CCD area-detector diffractometer	2136 independent reflections
Radiation source: normal-focus sealed tube	1741 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.026
ω scans	θ_max = 26.0°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −16→16
T_min = 0.876, T_max = 1.00	k = −11→11
8107 measured reflections	l = −23→23

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)] = 0.036	Hydrogen site location: difmap and geom
wR(F²) = 0.089	H atoms treated by a mixture of independent and constrained refinement
S = 1.11	w = 1/[σ²(F_o²) + (0.0378P)² + 1.6442P] where P = (F_o² + 2F_c²)/3
2136 reflections	(Δ/σ)_max < 0.001
181 parameters	Δρ_max = 0.27 e Å⁻³
0 restraints	Δρ_min = −0.24 e Å⁻³

Special details top

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
O1	0.69273 (9)	0.17756 (12)	0.31000 (6)	0.0242 (3)
O2	0.65689 (9)	0.41895 (12)	0.28976 (5)	0.0223 (3)
C1	0.67633 (11)	0.30840 (17)	0.33106 (8)	0.0164 (3)
C2	0.67789 (12)	0.33449 (18)	0.41112 (8)	0.0191 (3)
H2A	0.6072	0.3180	0.4228	0.023*
H2B	0.6963	0.4406	0.4220	0.023*
C3	0.75332 (11)	0.23416 (17)	0.45963 (7)	0.0154 (3)
H3	0.7347	0.1269	0.4490	0.019*
C4	0.86530 (12)	0.26014 (16)	0.44669 (8)	0.0152 (3)
O3	0.92444 (8)	0.14777 (12)	0.44635 (6)	0.0186 (3)
O4	0.89455 (8)	0.39294 (12)	0.43873 (6)	0.0217 (3)
C11	0.88420 (12)	0.74996 (17)	0.38683 (8)	0.0184 (3)
N11	0.89593 (12)	0.72249 (18)	0.45713 (8)	0.0250 (3)
N12	0.86122 (12)	0.63807 (16)	0.34127 (8)	0.0242 (3)
N13	0.89573 (11)	0.88714 (16)	0.36297 (8)	0.0229 (3)
C21	1.09697 (12)	0.31126 (17)	0.32844 (8)	0.0189 (3)
N21	1.06074 (12)	0.17722 (16)	0.34047 (8)	0.0235 (3)
N22	1.07380 (12)	0.42887 (16)	0.36587 (8)	0.0254 (3)
N23	1.15688 (12)	0.33132 (19)	0.27746 (8)	0.0277 (3)
H11A	0.8953 (16)	0.627 (3)	0.4689 (11)	0.040*
H11B	0.9314 (17)	0.789 (2)	0.4842 (12)	0.040*
H12A	0.8474 (16)	0.660 (2)	0.2957 (12)	0.040*
H12B	0.8585 (15)	0.546 (2)	0.3588 (11)	0.040*
H13A	0.9007 (15)	0.961 (2)	0.3922 (11)	0.040*
H13B	0.8822 (16)	0.901 (2)	0.3163 (12)	0.040*
H21A	1.0868 (16)	0.100 (2)	0.3232 (11)	0.040*
H21B	1.0202 (17)	0.168 (2)	0.3748 (11)	0.040*
H22A	1.0241 (17)	0.420 (2)	0.3933 (11)	0.040*
H22B	1.0961 (15)	0.520 (3)	0.3547 (11)	0.040*
H23A	1.1890 (16)	0.419 (3)	0.2769 (11)	0.040*
H23B	1.1784 (17)	0.251 (2)	0.2602 (12)	0.040*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0386 (7)	0.0178 (6)	0.0160 (6)	0.0017 (5)	0.0032 (5)	−0.0005 (4)
O2	0.0327 (7)	0.0192 (6)	0.0157 (5)	0.0032 (5)	0.0055 (5)	0.0016 (4)
C1	0.0139 (7)	0.0189 (8)	0.0164 (7)	−0.0013 (6)	0.0025 (6)	0.0010 (6)
C2	0.0196 (8)	0.0235 (8)	0.0145 (7)	0.0036 (6)	0.0035 (6)	−0.0001 (6)
C3	0.0176 (8)	0.0163 (7)	0.0127 (8)	0.0006 (6)	0.0034 (6)	−0.0011 (6)
C4	0.0199 (8)	0.0171 (8)	0.0087 (7)	0.0001 (6)	0.0027 (6)	−0.0005 (5)
O3	0.0190 (5)	0.0178 (6)	0.0200 (6)	0.0018 (4)	0.0056 (4)	−0.0017 (4)
O4	0.0243 (6)	0.0165 (6)	0.0250 (6)	−0.0013 (5)	0.0064 (5)	0.0032 (5)
C11	0.0157 (8)	0.0189 (8)	0.0203 (8)	0.0005 (6)	0.0014 (6)	−0.0005 (6)
N11	0.0326 (8)	0.0230 (8)	0.0185 (7)	−0.0053 (6)	0.0003 (6)	0.0003 (6)
N12	0.0377 (9)	0.0153 (7)	0.0173 (7)	−0.0007 (6)	−0.0034 (6)	0.0012 (6)
N13	0.0338 (8)	0.0176 (7)	0.0165 (7)	−0.0040 (6)	0.0010 (6)	−0.0020 (6)
C21	0.0152 (7)	0.0213 (8)	0.0200 (8)	0.0021 (6)	0.0019 (6)	0.0030 (6)
N21	0.0296 (8)	0.0184 (7)	0.0254 (7)	0.0017 (6)	0.0140 (6)	0.0005 (6)
N22	0.0278 (8)	0.0187 (7)	0.0314 (8)	−0.0022 (6)	0.0097 (6)	−0.0004 (6)
N23	0.0251 (8)	0.0312 (9)	0.0289 (8)	0.0022 (7)	0.0110 (6)	0.0067 (7)

Geometric parameters (Å, º) top

C1—O1	1.2608 (19)	N11—H11B	0.87 (2)
C1—O2	1.2596 (18)	N12—H12A	0.88 (2)
C1—C2	1.526 (2)	N12—H12B	0.89 (2)
C2—C3	1.532 (2)	N13—H13A	0.86 (2)
C2—H2A	0.9900	N13—H13B	0.88 (2)
C2—H2B	0.9900	C21—N21	1.317 (2)
C3—C4	1.533 (2)	C21—N22	1.324 (2)
C3—C3ⁱ	1.564 (3)	C21—N23	1.336 (2)
C3—H3	1.0000	N21—H21A	0.85 (2)
C4—O4	1.2597 (18)	N21—H21B	0.90 (2)
C4—O3	1.2651 (18)	N22—H22A	0.89 (2)
C11—N13	1.320 (2)	N22—H22B	0.89 (2)
C11—N12	1.323 (2)	N23—H23A	0.89 (2)
C11—N11	1.336 (2)	N23—H23B	0.85 (2)
N11—H11A	0.88 (2)

O2—C1—O1	123.88 (14)	C11—N11—H11A	115.1 (14)
O2—C1—C2	117.78 (13)	C11—N11—H11B	115.5 (14)
O1—C1—C2	118.33 (13)	H11A—N11—H11B	123 (2)
C1—C2—C3	114.73 (12)	C11—N12—H12A	117.5 (14)
C1—C2—H2A	108.6	C11—N12—H12B	118.2 (13)
C3—C2—H2A	108.6	H12A—N12—H12B	124.3 (19)
C1—C2—H2B	108.6	C11—N13—H13A	119.8 (14)
C3—C2—H2B	108.6	C11—N13—H13B	116.9 (14)
H2A—C2—H2B	107.6	H13A—N13—H13B	121.5 (19)
C4—C3—C2	111.16 (12)	N21—C21—N22	120.80 (15)
C4—C3—C3ⁱ	108.41 (14)	N21—C21—N23	120.48 (15)
C2—C3—C3ⁱ	110.83 (15)	N22—C21—N23	118.71 (15)
C4—C3—H3	108.8	C21—N21—H21A	119.7 (14)
C2—C3—H3	108.8	C21—N21—H21B	118.1 (13)
C3ⁱ—C3—H3	108.8	H21A—N21—H21B	120.6 (19)
O4—C4—O3	123.28 (14)	C21—N22—H22A	118.6 (14)
O4—C4—C3	118.23 (13)	C21—N22—H22B	118.9 (13)
O3—C4—C3	118.46 (13)	H22A—N22—H22B	120.6 (19)
N13—C11—N12	120.25 (15)	C21—N23—H23A	116.9 (14)
N13—C11—N11	120.42 (15)	C21—N23—H23B	115.0 (15)
N12—C11—N11	119.33 (15)	H23A—N23—H23B	124 (2)

Symmetry code: (i) −x+3/2, −y+1/2, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N11—H11A···O4	0.88 (2)	2.17 (2)	2.9591 (19)	150.1 (18)
N11—H11B···O3ⁱⁱ	0.87 (2)	2.20 (2)	2.9854 (18)	148.8 (19)
N12—H12A···O1ⁱⁱⁱ	0.88 (2)	1.99 (2)	2.8613 (18)	171 (2)
N12—H12B···O4	0.89 (2)	2.04 (2)	2.8495 (18)	151.3 (18)
N13—H13A···O3^iv	0.86 (2)	1.95 (2)	2.8013 (18)	170 (2)
N13—H13B···O2ⁱⁱⁱ	0.88 (2)	2.00 (2)	2.8788 (18)	175 (2)
N21—H21A···O2^v	0.85 (2)	2.00 (2)	2.8528 (18)	175 (2)
N21—H21B···O3	0.90 (2)	1.97 (2)	2.8712 (18)	177.0 (19)
N22—H22A···O4	0.89 (2)	2.02 (2)	2.8955 (19)	169.8 (19)
N22—H22B···O1^vi	0.89 (2)	2.14 (2)	2.9844 (19)	156.4 (18)
N23—H23A···O1^vi	0.89 (2)	2.39 (2)	3.170 (2)	147.0 (18)
N23—H23A···O2^vii	0.89 (2)	2.52 (2)	3.0010 (18)	114.7 (16)
N23—H23B···O1^vii	0.85 (2)	2.38 (2)	3.0632 (19)	138.1 (19)

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

Acknowledgements

The authors thank Loughborough University and Dorna Institute of Science for providing facilities. We also wish to acknowledge the use of the EPSRC's Chemical Database Service at Daresbury.

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