Bis(4-carboxy­pyridinium) aqua­pentakis­(iso­thio­cyanato-κN)iron(III) bis­(pyri­dinium-4-carboxyl­ate)

In the crystal structure of the title compound, (C₆H₆NO₂)₂[Fe(NCS)₅(H₂O)]·2C₆H₅NO₂, the iron complex lies on a mirror plane; the six-coordinate Fe^III ion, the coordinated water mol­ecule and three of the five isothio­cyanate ligands are located on this plane. The crystal structure is triple-layered. The pyridinium-4-carboxyl­ate (ina) mol­ecules and the protonated 4-carboxy­pyridinium (inaH⁺) cations inter­act with each other through N—H...O and O—H...O hydrogen bonds, leading to the formation of a layer perpendicular to the b axis. Pairs of these layers sandwich another layer of {[Fe(NCS)₅(H₂O)]²⁻}_n anions with which they inter­act via electrostatic attraction and O—H...O hydrogen bonds, resulting in sheets of triple layers also perpendicular to the b axis.

Key indicators

• Single-crystal X-ray study
• T = 297 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.049
• wR factor = 0.132
• Data-to-parameter ratio = 12.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    S3     -   C3      ..       6.27 su
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         N1
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         N2
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         N4
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Fe1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C2
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C4
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.20
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.43
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          1

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Fe1         (3)       3.20

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
  12 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
  10 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

---

S1. Comment

Isothiocyanate anions exhibit a large variety of different coordination modes towards metal cations and, partially due to this, they are widely used as versatile ligands in many areas of coordination chemistry (Li, Tong et al., 2004; Li, Zhao et al., 2004 and Li et al., 2007). Herein we describe the crystal structure of the iron(III) isothiocyanate complex [inaH]₂[Fe(H₂O)(NCS)₅].2[ina] (ina = isonicotinic acid).

A thermal ellipsoid drawing of the complex with the atomic numbering scheme is shown in Fig. 1. The iron complex lies on a mirror plane with the six-coordinated Fe^III ion, a coordinated water molecule and three of the five isothiocyanate ligands located directly within this plane (atoms Fe1, O1W, N1, C1, S1, N2, C2, S2, N4, C4 and S4). The coordination geometry around the Fe^III ion is slightly distorted octahedral. All the isothiocyanate anions coordinate to the iron(III) center through the nitrogen atoms in a slightly bent mode with C—N—Fe angles in the range of 150.7 (5)–166.8 (5)°. The ina molecules and the protonated inaH⁺ cations interact with each other through N—H···O and O—H···O hydrogen bonds which leads to the formation of a 2-D layer perpendicular to the b axis. One of this sublayers is shown in Fig. 2. Each two of these layers sandwich another layer of {[Fe(H₂O)(NCS)₅]^2-}_n anions with which they interact via electrostatic attraction and O—H···O hydrogen bonds, resulting in sheets of triple-layers perpendicular to the b axis. One of these triple-layers is shown in Fig. 3.

Related literature

For related compounds, see Li, Tong et al. (2004); Li, Zhao et al. (2004); Li et al. (2007).

S2. Experimental

AgNO₃ (0.51 g, 3.0 mmol), NH₄SCN (0.68 g, 4.5 mmol) and ina (1.11 g, 4.5 mmol) were added to a stirred solution of FeCl₃.6H₂O (0.41 g, 1.5 mmol) in water. The mixture was stirred at room temperature for 12 h. The solution was filtered and the filtrate was left to evaporate slowly in air. After a few days, purple-red crystals suitable for X-ray diffraction analysis were obtained.

S3. Refinement

Water and N—H hydrogen atoms were located from the difference density Fourier maps and were refined with U_iso(H) = 1.5U_eq(O) and U_iso(H) = 1.2U_eq(N). All other H atoms were placed geometrically with C–H and O—H distances of 0.96 and 0.82 Å and U_iso(H) = 1.2U_eq(C) or 1.5U_eq(O). Hydroxyl H atoms were allowed to rotate to best fit the experimental electron density.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SMART (Siemens, 1996) and SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996) and XPREP (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL (Bruker, 1999).

Figures

	Fig. 1. A view of the complex with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Symmetry code: (v) x, 3/2 - y, z.
	Fig. 2. The sublayer consisting of ina molcecules and inaH^+ cations. View along the b axis. Dashed lines represent N11—H11A··· O11^i, N21—H21A···O22^ii and O21—H21···O12^i hydrogen bonds. Symmetry codes: (i) x + 1/2, y, -z + 1/2; (ii) x - 1/2, y, -z + 3/2.
	Fig. 3. The triple-layer seen along the c axis. Dashed lines represent hydrogen bonding interactions.

Bis(4-carboxypyridinium) aquapentakis(isothiocyanato-κN)iron(III) bis(pyridinium-4-carboxylate)

Crystal data

(C6H6NO2)2[Fe(NCS)5(H2O)]·2C6H5NO2	F(000) = 1756
Mr = 858.72	Dx = 1.519 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 6815 reflections
a = 14.8713 (3) Å	θ = 1.9–25.1°
b = 21.0882 (3) Å	µ = 0.74 mm^−1
c = 11.9741 (2) Å	T = 297 K
V = 3755.18 (11) Å^3	Prism, purple red
Z = 4	0.36 × 0.30 × 0.20 mm

Data collection

Siemens SMART CCD diffractometer	3405 independent reflections
Radiation source: fine-focus sealed tube	2589 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.043
φ and ω scans	θmax = 25.0°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −15→17
Tmin = 0.776, Tmax = 0.866	k = −19→25
18247 measured reflections	l = −12→14

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.132	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.054P)^2 + 5.0802P] where P = (Fo^2 + 2Fc^2)/3
3405 reflections	(Δ/σ)max < 0.001
265 parameters	Δρmax = 0.71 e Å^−3
0 restraints	Δρmin = −0.62 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
Fe1	0.04898 (5)	0.7500	0.46892 (6)	0.0447 (2)
S1	0.35902 (12)	0.7500	0.57736 (16)	0.0711 (5)
S2	−0.26880 (10)	0.7500	0.44506 (14)	0.0618 (4)
S3	0.11872 (8)	0.53111 (5)	0.42450 (10)	0.0666 (3)
S4	0.08889 (14)	0.7500	0.84926 (17)	0.0966 (7)
N1	0.1841 (3)	0.7500	0.4965 (4)	0.0642 (13)
N2	−0.0851 (3)	0.7500	0.4331 (5)	0.0666 (14)
N3	0.0549 (2)	0.65311 (16)	0.4608 (3)	0.0571 (9)
N4	0.0261 (4)	0.7500	0.6327 (4)	0.0671 (14)
C1	0.2566 (4)	0.7500	0.5337 (4)	0.0492 (13)
C2	−0.1609 (4)	0.7500	0.4375 (4)	0.0481 (13)
C3	0.0825 (3)	0.6021 (2)	0.4464 (3)	0.0476 (9)
C4	0.0520 (4)	0.7500	0.7235 (5)	0.0577 (15)
O1W	0.0739 (3)	0.7500	0.2978 (3)	0.0556 (11)
H1WA	0.079 (3)	0.718 (2)	0.268 (4)	0.083*
O11	0.08724 (13)	0.63784 (11)	0.1885 (2)	0.0400 (6)
O12	0.13720 (17)	0.57069 (15)	0.0600 (2)	0.0676 (9)
N11	0.41185 (19)	0.61060 (15)	0.2733 (3)	0.0465 (8)
H11A	0.468 (3)	0.6149 (18)	0.292 (3)	0.056*
C11	0.1473 (2)	0.60535 (16)	0.1433 (3)	0.0390 (8)
C12	0.24110 (19)	0.60742 (15)	0.1927 (3)	0.0348 (7)
C13	0.3076 (2)	0.56935 (17)	0.1478 (3)	0.0439 (9)
H13A	0.2943	0.5423	0.0888	0.053*
C14	0.3928 (2)	0.57152 (18)	0.1900 (3)	0.0500 (10)
H14A	0.4374	0.5456	0.1603	0.060*
C15	0.3498 (2)	0.64714 (18)	0.3203 (3)	0.0490 (9)
H15A	0.3652	0.6735	0.3796	0.059*
C16	0.2630 (2)	0.64613 (17)	0.2814 (3)	0.0451 (9)
H16A	0.2192	0.6714	0.3147	0.054*
O21	0.48392 (16)	0.57804 (13)	0.5311 (2)	0.0567 (7)
H21	0.5353	0.5759	0.5065	0.085*
O22	0.55326 (17)	0.58175 (18)	0.6951 (2)	0.0807 (10)
N21	0.2356 (2)	0.61800 (19)	0.7871 (3)	0.0648 (10)
H21A	0.185 (3)	0.622 (2)	0.817 (4)	0.078*
C21	0.4867 (2)	0.58419 (18)	0.6386 (3)	0.0479 (9)
C22	0.3962 (2)	0.59533 (15)	0.6907 (3)	0.0374 (8)
C23	0.3176 (2)	0.58314 (18)	0.6341 (3)	0.0471 (9)
H23A	0.3195	0.5671	0.5617	0.057*
C24	0.2371 (2)	0.5946 (2)	0.6843 (3)	0.0600 (11)
H24A	0.1837	0.5861	0.6469	0.072*
C25	0.3097 (3)	0.6308 (2)	0.8439 (3)	0.0625 (11)
H25A	0.3058	0.6477	0.9155	0.075*
C26	0.3918 (2)	0.61910 (18)	0.7975 (3)	0.0505 (9)
H26A	0.4442	0.6271	0.8376	0.061*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.0430 (4)	0.0435 (4)	0.0475 (5)	0.000	0.0058 (3)	0.000
S1	0.0721 (11)	0.0533 (9)	0.0880 (12)	0.000	−0.0363 (9)	0.000
S2	0.0435 (8)	0.0693 (10)	0.0727 (11)	0.000	−0.0010 (7)	0.000
S3	0.0743 (8)	0.0469 (6)	0.0786 (8)	0.0132 (5)	−0.0133 (6)	0.0099 (5)
S4	0.0857 (13)	0.1384 (19)	0.0659 (12)	0.000	−0.0134 (10)	0.000
N1	0.052 (3)	0.069 (3)	0.071 (4)	0.000	−0.003 (3)	0.000
N2	0.046 (3)	0.070 (3)	0.084 (4)	0.000	−0.002 (3)	0.000
N3	0.071 (2)	0.045 (2)	0.055 (2)	−0.0017 (17)	0.0016 (17)	0.0027 (16)
N4	0.083 (4)	0.069 (3)	0.049 (3)	0.000	0.010 (3)	0.000
C1	0.065 (4)	0.040 (3)	0.043 (3)	0.000	0.001 (3)	0.000
C2	0.055 (4)	0.042 (3)	0.047 (3)	0.000	0.003 (3)	0.000
C3	0.049 (2)	0.053 (2)	0.041 (2)	−0.0067 (19)	−0.0052 (16)	0.0108 (17)
C4	0.049 (3)	0.060 (4)	0.064 (4)	0.000	0.012 (3)	0.000
O1W	0.078 (3)	0.038 (2)	0.050 (2)	0.000	0.011 (2)	0.000
O11	0.0217 (11)	0.0482 (14)	0.0502 (15)	0.0011 (10)	0.0022 (10)	−0.0036 (11)
O12	0.0392 (15)	0.085 (2)	0.078 (2)	0.0187 (14)	−0.0255 (14)	−0.0423 (17)
N11	0.0213 (14)	0.059 (2)	0.059 (2)	−0.0046 (14)	−0.0074 (14)	0.0054 (16)
C11	0.0261 (16)	0.046 (2)	0.045 (2)	0.0029 (15)	−0.0061 (15)	−0.0062 (16)
C12	0.0229 (15)	0.0407 (18)	0.0407 (19)	−0.0011 (13)	−0.0005 (13)	−0.0001 (14)
C13	0.0303 (17)	0.051 (2)	0.050 (2)	0.0044 (15)	−0.0023 (16)	−0.0119 (17)
C14	0.0283 (18)	0.056 (2)	0.066 (3)	0.0076 (16)	0.0033 (17)	−0.003 (2)
C15	0.0357 (18)	0.064 (2)	0.048 (2)	0.0000 (18)	−0.0113 (16)	−0.0103 (18)
C16	0.0301 (17)	0.058 (2)	0.047 (2)	0.0069 (16)	−0.0019 (15)	−0.0123 (17)
O21	0.0323 (13)	0.087 (2)	0.0512 (17)	0.0029 (13)	0.0102 (11)	0.0048 (14)
O22	0.0307 (15)	0.149 (3)	0.0622 (19)	0.0025 (16)	−0.0062 (14)	0.0092 (19)
N21	0.0378 (19)	0.093 (3)	0.064 (2)	0.0102 (18)	0.0123 (17)	−0.011 (2)
C21	0.0315 (19)	0.058 (2)	0.054 (2)	−0.0050 (16)	0.0036 (17)	0.0099 (18)
C22	0.0290 (17)	0.0373 (18)	0.046 (2)	−0.0035 (14)	0.0001 (14)	0.0040 (15)
C23	0.0335 (18)	0.064 (2)	0.044 (2)	−0.0017 (17)	0.0034 (16)	−0.0057 (18)
C24	0.031 (2)	0.092 (3)	0.058 (3)	−0.001 (2)	−0.0012 (18)	−0.007 (2)
C25	0.062 (3)	0.074 (3)	0.051 (2)	0.003 (2)	0.010 (2)	−0.018 (2)
C26	0.043 (2)	0.060 (2)	0.049 (2)	−0.0076 (17)	−0.0031 (17)	−0.0084 (18)

Geometric parameters (Å, º)

Fe1—N4	1.991 (5)	C12—C13	1.383 (4)
Fe1—N1	2.037 (5)	C13—C14	1.365 (5)
Fe1—N2	2.039 (5)	C13—H13A	0.9300
Fe1—N3	2.047 (3)	C14—H14A	0.9300
Fe1—N3^i	2.047 (3)	C15—C16	1.373 (5)
Fe1—O1W	2.082 (4)	C15—H15A	0.9300
S1—C1	1.610 (6)	C16—H16A	0.9300
S2—C2	1.607 (6)	O21—C21	1.294 (4)
S3—C3	1.613 (4)	O21—H21	0.8200
S4—C4	1.602 (7)	O22—C21	1.201 (4)
N1—C1	1.167 (7)	N21—C25	1.323 (5)
N2—C2	1.129 (7)	N21—C24	1.325 (5)
N3—C3	1.164 (5)	N21—H21A	0.84 (4)
N4—C4	1.153 (7)	C21—C22	1.502 (5)
O1W—H1WA	0.76 (4)	C22—C26	1.375 (5)
O11—C11	1.249 (4)	C22—C23	1.375 (5)
O12—C11	1.246 (4)	C23—C24	1.361 (5)
N11—C14	1.325 (5)	C23—H23A	0.9300
N11—C15	1.327 (5)	C24—H24A	0.9300
N11—H11A	0.86 (4)	C25—C26	1.364 (5)
C11—C12	1.515 (4)	C25—H25A	0.9300
C12—C16	1.378 (5)	C26—H26A	0.9300
N4—Fe1—N1	90.5 (2)	C14—C13—H13A	120.0
N4—Fe1—N2	92.3 (2)	C12—C13—H13A	120.0
N1—Fe1—N2	177.2 (2)	N11—C14—C13	119.9 (3)
N4—Fe1—N3	93.10 (10)	N11—C14—H14A	120.1
N1—Fe1—N3	87.99 (10)	C13—C14—H14A	120.1
N2—Fe1—N3	91.85 (10)	N11—C15—C16	120.1 (3)
N4—Fe1—N3^i	93.10 (10)	N11—C15—H15A	120.0
N1—Fe1—N3^i	87.99 (10)	C16—C15—H15A	120.0
N2—Fe1—N3^i	91.85 (10)	C15—C16—C12	119.5 (3)
N3—Fe1—N3^i	172.64 (19)	C15—C16—H16A	120.3
N4—Fe1—O1W	179.6 (2)	C12—C16—H16A	120.3
N1—Fe1—O1W	89.1 (2)	C21—O21—H21	109.5
N2—Fe1—O1W	88.1 (2)	C25—N21—C24	122.6 (3)
N3—Fe1—O1W	86.88 (10)	C25—N21—H21A	120 (3)
N3^i—Fe1—O1W	86.88 (10)	C24—N21—H21A	117 (3)
C1—N1—Fe1	166.8 (5)	O22—C21—O21	125.6 (3)
C2—N2—Fe1	165.2 (5)	O22—C21—C22	120.7 (3)
C3—N3—Fe1	160.8 (3)	O21—C21—C22	113.6 (3)
C4—N4—Fe1	150.7 (5)	C26—C22—C23	119.1 (3)
N1—C1—S1	176.4 (5)	C26—C22—C21	119.1 (3)
N2—C2—S2	179.5 (6)	C23—C22—C21	121.8 (3)
N3—C3—S3	178.7 (4)	C24—C23—C22	119.7 (3)
N4—C4—S4	179.5 (6)	C24—C23—H23A	120.2
Fe1—O1W—H1WA	118 (4)	C22—C23—H23A	120.2
C14—N11—C15	122.1 (3)	N21—C24—C23	119.5 (4)
C14—N11—H11A	118 (3)	N21—C24—H24A	120.3
C15—N11—H11A	120 (3)	C23—C24—H24A	120.3
O12—C11—O11	125.6 (3)	N21—C25—C26	120.0 (4)
O12—C11—C12	116.1 (3)	N21—C25—H25A	120.0
O11—C11—C12	118.3 (3)	C26—C25—H25A	120.0
C16—C12—C13	118.4 (3)	C25—C26—C22	119.1 (3)
C16—C12—C11	122.3 (3)	C25—C26—H26A	120.4
C13—C12—C11	119.3 (3)	C22—C26—H26A	120.4
C14—C13—C12	120.0 (3)

Symmetry code: (i) x, −y+3/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O11	0.76 (4)	1.95 (4)	2.711 (3)	178 (5)
N11—H11A···O11^ii	0.86 (4)	1.86 (4)	2.710 (3)	168 (4)
O21—H21···O12^ii	0.82	1.72	2.532 (3)	173
N21—H21A···O22^iii	0.84 (4)	2.14 (5)	2.825 (4)	138 (4)

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