An ordered low-temperature phase of barium nitro­prusside trihydrate studied by neutron diffraction

Crystals of barium penta­cyano­nitro­syl­ferrate trihydrate (barium nitro­prusside trihydrate), Ba[Fe(CN)₅(NO)]·3H₂O, have been studied by neutron diffraction in order to ex­amine the structural behaviour of the compound in the 20-120 K temperature range and to determine the structure at 105 K. The results show the existence of a new crystal phase of the compound at 80 K (with a duplicated a parameter), which still exists at 20 K. The crystal structure at 105 K shows a rearrangement of the water mol­ecules, which results in an ordered structure with P1 symmetry. Two of the four independent nitro­prusside cations are rotated by 4.5° around the [100] direction.

S1. Comment

Barium nitroprusside trihydrate, (I), (hereafter BaNP·3 W) belongs to the nitroprusside family, in which the nitroprusside anion can be photoexcited reversibly to two long-living metastable states, MSI and MSII, at low temperature (Zöllner et al., 1989; Soria et al., 2002; Woike et al., 2002; Güida et al., 1993). The nitroprusside anion is currently being used in the search for new materials that combine photochromic and magnetic or electroconducting properties in the same crystal (Bellouard et al., 2001; Zorina et al., 2002).

X-ray diffraction studies of BaNP·3 W at room temperature (Lanfranconi et al., 1973; Retzlaff et al.,1989) evidence the presence of weakly bonded water molecules and the existence of strong dipolar interactions between the nitrosyl ligands. The peculiar system of weak hydrogen bonds induces phase transitions in the crystals of BaNP·3 W, three of which have been detected by DTA (at 233.4, 130.2 and 118.0 K) and ¹⁴N-NQR (at 233, 131 and 118 K) experiments (Guida, 1992; Murgich et al., 1990). As a consequence of its characteristic crystal packing, BaNP·3 W has been used to study the origin and magnitude of correlation (Davidov) splitting effects due to the coupling between strongly polar vibrations of neighbouring anions in the crystal lattice (Piro et al., 1987; Güida et al., 1992).

From the analysis of the behaviour of selected reflections as a function of temperature, decreasing from 295 to 77 K, the first neutron diffraction study of BaNP·3 W detected phase transitions at 130 K and 112 K (Navaza et al., 1990). Between these two temperatures, commensurate superlattice reflections appear, suggesting a duplication of the crystal a parameter. Below 112 K, additional reflections, which are forbidden at room temperature (space group Pbcm), are observed and the superlattice reflections disappear. However, near 233 K, no anomaly in reciprocal space could be detected; comparison between the neutron structures at 140 and 295 K confirmed this phase transition (Navaza et al., 1992; Navaza et al., 1990).

The neutron crystal structure at 295 K was refined in space group Pbcm. At this temperature, positional disorder affects two water molecules, viz. W3 and W4. The neutron structure at 140 K shows positional disorder of only molecule W4; this structure was refined in space group Pca2₁. NMR studies have further shown that the positional disorder of the water molecules is dynamic (Tritt-Goc et al., 1994; Tritt-Goc, 1995).

We have undertaken a new neutron diffraction study of BaNP·3 W in an attempt to confirm the existence of a fourth phase transition at 80 K, suggested by anomalies observed in Raman and IR spectra (Güida, 1992), and to determine the structure below 112 K.

The intensity evolution of selected reflections was analyzed as a function of temperature in the 20–140 K range. As an example, Fig. 1 shows the behaviour of the (071) reflection, which is forbidden in space groups Pbcm and Pca2₁. Similar behaviour was observed at the time of the first neutron diffraction study of BaNP·3 W. At 20 K, the (071) reflection and the two commensurate superlattice reflections, (+0.5 7 1) and (−0.5 7 1), are visible. The latter begin to vanish at 80 K and disappears completely at 95 K, whereas the intensity of the (0 7 1) reflection increases, reaching its maximum at 105 K, and then disappears at 130 K. Between 110 and 130 K, the commensurate reflections are present. These results confirm the existence of another crystal phase of the BaNP·3 W at 80 K, which still exists at 20 K.

To determine the crystal phase of BaNP·3 W between 80 and 110 K, a complete neutron diffraction data set has been collected at 105 K. These measurements show the significant intensity of some reflections forbidden by the Pca2₁ space group and its subgroups P2₁ and Pc. Thus, the space group of BaNP·3 W at 105 K is P1. The cell volume is slightly greater (2%) than that at 140 K but is equivalent to that at room temperature. The angle α is not 90° within the standard uncertainty.

In this structure, the BaNP·3 W molecule occupy four independent sites, labelled 1, 2, 3 and 4 in Fig. 2. The increasing number of anions in the asymmetric unit had been foreseen by Murgich (1990) using ¹⁴N-NQR spectra. Large positional variations of the water molecules (W2, W3 and W4) are observed, which break the Pca2₁ symmetry of the 140 K crystal phase.

Molecule W2, coordinated to the Ba²⁺ anion, connects the nitroprusside anions along the [010] direction. In the structure at 105 K, we observed a significant increase of the average H1···N3 (2.85 Å) and H2···N5 (2.71 Å) distances (−2.56 and 2.37 Å, respectively at 140 K), and a decrease of the H1···N4 (2.50 Å) and H2···N6 (2.62 Å) distances (2.89 Å and 2.90 Å, respectively at 140 K). This distance variation indicates that the interactions between molecule W2 and atoms N4 and N6 are particularly strengthened in sites 3 and 4 (Table 2).

At 295 K, molecule W3 is crystallographically disordered over two positions, as shown in Fig. 3; at 140 K, it occupies a single position. At this temperature, molecule W3 is involved in a two-centre hydrogen bond with atoms N2 (via atom H32) and N3 (via atom H31) of the same nitroprusside anion. At 105 K, in sites 1 and 2, molecule W3 rotates 80° around the O3—H32₁₄₀ axis and moves by 0.6 Å. In sites 3 and 4, the changes are not significant. The O3—H32···N2 hydrogen bond exists for all four sites, but the O3—H31···N3₁₄₀ interaction is replaced by an O3—H31···N6 interaction in sites 1 and 2 (Table 2).

Molecule W4 is disordered in two positions, with occupancies of 0.5 and 0.5 at 295 K, and of 0.7 and 0.3 at 140 K (labelled W4 and W5, respectively, in Fig. 3; one of the W4 H atoms is in the same postion as one of the W5 H atoms?. At 105 K, W4 has an occupancy of 1 in the four inequivalent sites 1, 2, 3 and 4. In sites 3 and 4, molecule W4 keeps the same orientation as W4₁₄₀ and forms similar hydrogen bonds. In sites 1 and 2, molecule W4 rotates 170° around the O5—H51₁₄₀ axis and moves more than 0.7 Å. The new O4—H41···N4 hydrogen bonds are significantly reinforced. The rotation of molecule W3 (sites 1 and 2) permits this molecule accept hydrogen bonds from the new positions of molecule W4, via atom H42 (Table 2).

The principal structural differences between the four independent nitroprusside anions refined at 105 K and the nitroprusside anion refined at 140 K are related to the acceptor atoms of the hydrogen bonds. The C—N bond distances are a little longer [<CN>₁₀₅ = 1.178 (8) Å versus <CN>₁₄₀= 1.157 (8) Å], particularly for the C4—N4 bond corresponding to sites 3 and 4 [1.20 (1)–1.21 (1) versus 1.166 (4) Å]. Furthermore, in sites 3 and 4, the C3—Fe—C4 angles are larger [90.8 (6)–90.2 (6) versus 88.5 (2) Å], the C5—Fe—C6 angles are smaller [88.8 (6)–88.3 (6) versus 91.0 (2) Å], the Fe—C4—N4 are smaller [174 (1)–176 (1) versus 179.1 (3) Å] and the Fe—C5—N5 are larger [178 (1)–178 (1) versus 175.2 (3) Å). The nitroprusside anions occupying sites 3 and 4 keep the same orientation as those of the structure at 140 K, while the nitroprusside anions occupying sites 1 and 2 rotate ~4.5° around the [1 0 0] axis.

The coordination polyhedron around the Ba²⁺ cation is a triply capped trigonal prism, with atoms OW2, N2 and OW3 capping the polyhedron faces. Molecules W2 and W3 are coordinated to one Ba²⁺ atom and molecule W4 is shared between two consecutive cations, thus forming infinite chains of coordination polyhedra parallel to the [0 0 1] direction. The chains placed in the (0 y z) and (1/2 y z) unit-cell planes are not structurally equivalent; the differences may be explained in terms of positional variations of molecules W3 and W4. The rotation? and the high displacement of molecule W4 in sites 1 and 2 induce some geometric differences. As observed in the structure at 140 K, the O3—H31···N3 hydrogen bonds corresponding to sites 3 and 4 reinforce the intrachain cohesion. Conversely, the O3—H31···N6 hydrogen bonds observed in sites 1 and 2 connect consecutive chains in the [0 1 0] direction.

In conclusion, positional changes of the water molecules induce an ordered structure in space group P1, with concomitant changes to the hydrogen bonding and a rotation of 4.5° of the nitroprusside cations lying in sites 1 and 2. This new study confirms the existence of a fourth phase transition, at 80 K, in crystals of BaNP·3 W.

These results show the important role played by weakly bonded water molecules in these low-temperature phase transitions.

S2. Experimental

BaNP·3 W was obtained by adding a stoichiometric quantity of silver nitroprusside (prepared by precipitation from stoichiometric amounts of sodium nitroprusside and silver nitrate solutions) to a solution of barium chloride, with stirring. Silver chloride was separated from the solution by filtration and the liquid was concentrated in a rotator vacuum evaporator at room temperature to obtain crystals of BaNP·3 W. Large single crystals were grown from small crystals by the hanging-seed method, by spontaneous concentration of saturated aqueous solutions kept in a thermostat slightly above room temperature.

S3. Refinement

The crystal, closed into an aluminium container at atmospheric conditions, was cooled directly to 20 K with a cooling rate of 3 K min_-1. The cooling experimental conditions prevented the collection of a complete set of diffracted reflections. The structure of (I) at 105 K was determined in space group P1. Water molecules were placed from difference Fourier maps, phased with refined positions and isotropic displacement parameters for all nitroprusside atoms. High correlations and the low ratio of the number of refined parameters to the number of independent reflection obliged us to refine H and cyanide atoms isotropically, and to constrain the isotropic or anisotropic displacement parameters of all atoms occuping pseudosymmetric positions to be identical. The absolute value of the largest residual peak was smaller than 20% of the peak associated to a removed C atom.

Computing details

Program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: CAMERON (Pearce et al., 2000); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The variation of the (0 7 1) reflection and of the (0.5 7 1) and (−0.5 7 1) superlattice reflection intensities with increasing temperature (20–140 K).
	Fig. 2. A perspective view of the unit cell of (I). For the sake of clarity, only a few labels are included. Four independent pseudosymmetric nitroprusside anions occupy sites differentiated by the last number in the name. Dotted lines represent possible hydrogen bonds.
	Fig. 3. The positions of the disorded W3 and W4/W5 water molecules lying close to the a/2 plan at 295, 140 and 105 K (sites 1 and 2). The perspective view is the same as Fig 2.

(I)

Crystal data

Ba[Fe(CN)5(NO)]·3H2O	Z = 4
Mr = 407.31	F(000) = 419.0
Triclinic, P1	Dx = 2.120 Mg m^−3
a = 19.01 (9) Å	Neutron radiation, λ = 1.548 (5) Å
b = 7.694 (16) Å	Cell parameters from 33 reflections
c = 8.72 (2) Å	θ = 15.5–24.2°
α = 90.040 (3)°	µ = 0.16 mm^−1
β = 90.003 (5)°	T = 105 K
γ = 89.994 (5)°	Parallelepiped, brown-red
V = 1276 (7) Å^3	5.5 × 2.5 × 1.5 mm

Data collection

Four-circle diffractometer, 6T2 Orphee reactor	2260 reflections with I > 2σ(I)
Radiation source: Orphee reactor	Rint = 0.007
Er filters monochromator	θmax = 55.0°, θmin = 2.3°
ω 3<2θ<50 ω–θ 50<2θ<80 ω–2θ 80<2θ<110 scans	h = −18→6
Absorption correction: numerical laboratory program	k = −8→8
Tmin = 0.498, Tmax = 0.793	l = −9→9
2453 measured reflections	2 standard reflections every 100 reflections
2415 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.078	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.087	w = 1/(σ^2Fo^2) where P = (Fo^2 + 2Fc^2)/3
S = 3.75	(Δ/σ)max < 0.001
2415 reflections	Δρmax = 0.98 e Å^−3
340 parameters	Δρmin = −1.09 e Å^−3
3 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00229 (10)

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 on F² for ALL reflections except for 0 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating _R_factor_obs 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
Ba1	0.4013 (9)	0.922 (2)	0.2492 (17)	0.0128 (10)
Ba2	0.6067 (9)	0.070 (2)	0.7499 (17)	0.0128 (10)
Ba3	0.1039 (9)	0.927 (2)	0.7478 (16)	0.0128 (10)
Ba4	0.8999 (9)	0.074 (2)	0.2482 (17)	0.0128 (10)
Fe1	0.6645 (5)	0.5806 (11)	0.2484 (9)	0.0085 (6)
Fe2	0.3389 (5)	0.4179 (11)	0.7487 (9)	0.0085 (6)
Fe3	0.8392 (5)	0.5817 (11)	0.7486 (9)	0.0085 (6)
Fe4	0.1649 (5)	0.4186 (11)	0.2489 (9)	0.0085 (6)
O1	0.8120 (9)	0.543 (2)	0.2445 (17)	0.0248 (12)
O2	0.1927 (10)	0.453 (2)	0.7446 (17)	0.0248 (12)
O3	0.6914 (9)	0.548 (2)	0.7545 (16)	0.0248 (12)
O4	0.3107 (9)	0.457 (2)	0.2564 (16)	0.0248 (12)
N11	0.7526 (6)	0.5594 (12)	0.2465 (9)	0.0122 (6)
N12	0.2515 (6)	0.4432 (12)	0.7462 (9)	0.0122 (6)
N13	0.7518 (5)	0.5552 (12)	0.7531 (9)	0.0122 (6)
N14	0.2525 (5)	0.4431 (12)	0.2539 (9)	0.0122 (6)
N21	0.5028 (5)	0.6469 (12)	0.2589 (9)	0.0194 (7)*
N22	0.5012 (5)	0.3475 (12)	0.7607 (9)	0.0194 (7)*
N23	1.0007 (5)	0.6485 (12)	0.7384 (9)	0.0194 (7)*
N24	0.0031 (5)	0.3497 (12)	0.2385 (9)	0.0194 (7)*
N31	0.6396 (5)	0.3033 (11)	0.5037 (9)	0.0206 (11)*
N32	0.3646 (5)	0.6939 (11)	1.0046 (9)	0.0206 (11)*
N33	0.8743 (5)	0.2905 (11)	0.9881 (9)	0.0206 (11)*
N34	0.1299 (5)	0.7090 (11)	0.4860 (9)	0.0206 (11)*
N41	0.6629 (5)	0.8711 (12)	0.4993 (10)	0.0194 (12)*
N42	0.3411 (5)	0.1267 (11)	0.9992 (10)	0.0194 (12)*
N43	0.8467 (5)	0.8553 (11)	1.0106 (9)	0.0194 (12)*
N44	0.1577 (5)	0.1432 (11)	0.5100 (9)	0.0194 (12)*
N51	0.6575 (5)	0.8545 (11)	−0.0109 (10)	0.0207 (13)*
N52	0.3459 (5)	0.1434 (11)	0.4878 (10)	0.0207 (13)*
N53	0.8413 (5)	0.8709 (12)	0.4986 (10)	0.0207 (13)*
N54	0.1632 (5)	0.1266 (12)	−0.0009 (10)	0.0207 (13)*
N61	0.6302 (5)	0.2900 (11)	0.0115 (9)	0.0210 (11)*
N62	0.3744 (5)	0.7070 (11)	0.5111 (9)	0.0210 (11)*
N63	0.8647 (5)	0.3034 (11)	0.4940 (9)	0.0210 (11)*
N64	0.1400 (5)	0.6955 (11)	−0.0045 (9)	0.0210 (11)*
C21	0.5642 (7)	0.6200 (16)	0.2581 (13)	0.0145 (9)*
C22	0.4408 (7)	0.3776 (16)	0.7567 (13)	0.0145 (9)*
C23	0.9404 (8)	0.6215 (17)	0.7460 (13)	0.0145 (9)*
C24	0.0635 (8)	0.3786 (17)	0.2454 (13)	0.0145 (9)*
C31	0.6496 (6)	0.4111 (15)	0.4102 (13)	0.0139 (16)*
C32	0.3549 (6)	0.5865 (15)	0.9106 (13)	0.0139 (16)*
C33	0.8601 (7)	0.4007 (15)	0.8975 (13)	0.0139 (16)*
C34	0.1437 (7)	0.5974 (16)	0.3973 (13)	0.0139 (16)*
C41	0.6644 (7)	0.7668 (15)	0.4027 (13)	0.0126 (17)*
C42	0.3388 (7)	0.2368 (17)	0.9030 (13)	0.0126 (17)*
C43	0.8410 (7)	0.7547 (16)	0.9062 (13)	0.0126 (17)*
C44	0.1626 (7)	0.2473 (16)	0.4072 (13)	0.0126 (17)*
C51	0.6617 (7)	0.7527 (17)	0.0855 (13)	0.0130 (17)*
C52	0.3409 (7)	0.2498 (15)	0.5850 (13)	0.0130 (17)*
C53	0.8391 (7)	0.7615 (16)	0.5914 (14)	0.0130 (17)*
C54	0.1645 (7)	0.2373 (17)	0.0904 (14)	0.0130 (17)*
C61	0.6435 (6)	0.3981 (15)	0.1023 (12)	0.0120 (16)*
C62	0.3599 (6)	0.5993 (15)	0.6006 (12)	0.0120 (16)*
C63	0.8547 (6)	0.4089 (15)	0.5879 (13)	0.0120 (16)*
C64	0.1489 (7)	0.5884 (15)	0.0889 (13)	0.0120 (16)*
O21	0.2542 (9)	0.892 (2)	0.2572 (18)	0.0163 (10)
O22	0.7493 (9)	0.114 (2)	0.7535 (17)	0.0163 (10)
O23	0.2511 (9)	0.892 (2)	0.7450 (18)	0.0163 (10)
O24	0.7573 (9)	0.112 (2)	0.2454 (17)	0.0163 (10)
O31	0.4801 (7)	0.2487 (17)	0.2134 (14)	0.0183 (14)
O32	0.5255 (7)	0.7521 (18)	0.7154 (15)	0.0183 (14)
O33	0.0245 (7)	0.2480 (17)	0.7803 (14)	0.0183 (14)
O34	0.9790 (7)	0.7504 (17)	0.2831 (15)	0.0183 (14)
O41	0.4877 (7)	0.9731 (19)	0.9612 (13)	0.0246 (15)
O42	0.5168 (7)	0.0249 (18)	0.4616 (13)	0.0246 (15)
O43	−0.0144 (7)	0.0177 (18)	0.5366 (13)	0.0246 (15)
O44	0.0178 (7)	0.9797 (18)	0.0375 (13)	0.0246 (15)
H211	0.2290 (16)	0.929 (3)	0.334 (3)	0.042 (3)*
H212	0.7791 (14)	0.063 (3)	0.841 (3)	0.042 (3)*
H213	0.2763 (15)	0.932 (3)	0.828 (3)	0.042 (3)*
H214	0.7268 (15)	0.066 (3)	0.335 (3)	0.042 (3)*
H221	0.2254 (15)	0.882 (3)	0.164 (3)	0.042 (4)*
H222	0.7791 (15)	0.111 (3)	0.671 (3)	0.042 (4)*
H223	0.2804 (15)	0.886 (3)	0.664 (3)	0.042 (4)*
H224	0.7226 (14)	0.109 (3)	0.155 (3)	0.042 (4)*
H311	0.5115 (14)	0.247 (3)	0.134 (3)	0.052 (5)*
H321	0.4707 (14)	0.371 (4)	0.228 (3)	0.040 (4)*
H312	0.4931 (14)	0.750 (3)	0.634 (3)	0.052 (5)*
H322	0.5305 (14)	0.635 (4)	0.725 (3)	0.040 (4)*
H313	−0.0091 (15)	0.250 (3)	0.866 (3)	0.059 (5)*
H323	0.0318 (16)	0.363 (4)	0.762 (3)	0.042 (4)*
H314	1.0116 (16)	0.748 (3)	0.359 (3)	0.059 (5)*
H324	0.9731 (16)	0.629 (4)	0.259 (3)	0.042 (4)*
H411	0.4419 (16)	1.043 (3)	0.925 (3)	0.066 (5)*
H421	0.4841 (11)	0.872 (3)	0.917 (3)	0.037 (4)*
H412	0.5620 (16)	−0.043 (3)	0.429 (3)	0.066 (5)*
H422	0.5209 (11)	0.127 (3)	0.420 (2)	0.037 (4)*
H413	−0.0557 (14)	−0.036 (3)	0.572 (3)	0.053 (5)*
H423	−0.0171 (13)	0.129 (3)	0.585 (3)	0.050 (4)*
H414	0.0219 (13)	0.873 (3)	0.083 (3)	0.053 (5)*
H424	0.0595 (14)	1.038 (3)	0.074 (3)	0.050 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.012 (3)	0.0116 (19)	0.015 (2)	−0.003 (2)	0.0032 (19)	−0.0012 (17)
Ba2	0.012 (3)	0.0116 (19)	0.015 (2)	−0.003 (2)	0.0032 (19)	−0.0012 (17)
Ba3	0.012 (3)	0.0116 (19)	0.015 (2)	−0.003 (2)	0.0032 (19)	−0.0012 (17)
Ba4	0.012 (3)	0.0116 (19)	0.015 (2)	−0.003 (2)	0.0032 (19)	−0.0012 (17)
Fe1	0.0064 (15)	0.0088 (11)	0.0104 (11)	−0.0011 (10)	0.0041 (9)	−0.0044 (9)
Fe2	0.0064 (15)	0.0088 (11)	0.0104 (11)	−0.0011 (10)	0.0041 (9)	−0.0044 (9)
Fe3	0.0064 (15)	0.0088 (11)	0.0104 (11)	−0.0011 (10)	0.0041 (9)	−0.0044 (9)
Fe4	0.0064 (15)	0.0088 (11)	0.0104 (11)	−0.0011 (10)	0.0041 (9)	−0.0044 (9)
O1	0.015 (3)	0.033 (3)	0.026 (3)	0.002 (3)	0.005 (2)	−0.006 (2)
O2	0.015 (3)	0.033 (3)	0.026 (3)	0.002 (3)	0.005 (2)	−0.006 (2)
O3	0.015 (3)	0.033 (3)	0.026 (3)	0.002 (3)	0.005 (2)	−0.006 (2)
O4	0.015 (3)	0.033 (3)	0.026 (3)	0.002 (3)	0.005 (2)	−0.006 (2)
N11	0.008 (2)	0.0157 (13)	0.0131 (13)	0.0001 (10)	0.0048 (11)	−0.0027 (10)
N12	0.008 (2)	0.0157 (13)	0.0131 (13)	0.0001 (10)	0.0048 (11)	−0.0027 (10)
N13	0.008 (2)	0.0157 (13)	0.0131 (13)	0.0001 (10)	0.0048 (11)	−0.0027 (10)
N14	0.008 (2)	0.0157 (13)	0.0131 (13)	0.0001 (10)	0.0048 (11)	−0.0027 (10)
O21	0.010 (3)	0.020 (3)	0.019 (3)	−0.002 (2)	0.004 (2)	0.001 (2)
O22	0.010 (3)	0.020 (3)	0.019 (3)	−0.002 (2)	0.004 (2)	0.001 (2)
O23	0.010 (3)	0.020 (3)	0.019 (3)	−0.002 (2)	0.004 (2)	0.001 (2)
O24	0.010 (3)	0.020 (3)	0.019 (3)	−0.002 (2)	0.004 (2)	0.001 (2)
O31	0.013 (3)	0.021 (3)	0.020 (4)	0.001 (2)	0.010 (3)	0.000 (3)
O32	0.013 (3)	0.021 (3)	0.020 (4)	0.001 (2)	0.010 (3)	0.000 (3)
O33	0.013 (3)	0.021 (3)	0.020 (4)	0.001 (2)	0.010 (3)	0.000 (3)
O34	0.013 (3)	0.021 (3)	0.020 (4)	0.001 (2)	0.010 (3)	0.000 (3)
O41	0.014 (4)	0.033 (3)	0.027 (4)	0.004 (3)	0.006 (3)	−0.001 (3)
O42	0.014 (4)	0.033 (3)	0.027 (4)	0.004 (3)	0.006 (3)	−0.001 (3)
O43	0.014 (4)	0.033 (3)	0.027 (4)	0.004 (3)	0.006 (3)	−0.001 (3)
O44	0.014 (4)	0.033 (3)	0.027 (4)	0.004 (3)	0.006 (3)	−0.001 (3)

Geometric parameters (Å, º)

Ba1—O21	2.81 (3)	N54—C54	1.166 (15)
Ba1—O31^i	2.94 (2)	N61—C61	1.175 (13)
Ba1—O42^i	2.98 (2)	N62—C62	1.171 (13)
Ba1—O41^ii	3.03 (2)	N63—C63	1.169 (13)
Ba2—O22	2.73 (3)	N64—C64	1.171 (14)
Ba2—O32^iii	2.91 (2)	C32—N32	1.178 (14)
Ba2—O41^iii	3.01 (2)	C42—N42	1.194 (14)
Ba2—O42	3.06 (2)	C43—N43	1.200 (14)
Ba3—O23	2.81 (3)	C64—N64	1.171 (14)
Ba3—O33^i	2.91 (2)	O21—H211	0.87 (4)
Ba3—O43^i	2.99 (2)	O21—H221	0.98 (4)
Ba3—O44^iv	3.04 (2)	O22—H212	1.03 (4)
Ba4—O24	2.73 (3)	O22—H222	0.92 (4)
Ba4—O34^iii	2.93 (2)	O23—H213	0.92 (4)
Ba4—O44^v	2.99 (2)	O23—H223	0.90 (4)
Ba4—O43^vi	3.03 (2)	O24—H214	1.03 (4)
Fe1—N11	1.683 (17)	O24—H224	1.03 (4)
Fe1—C21	1.933 (19)	O31—O42	2.854 (18)
Fe1—C61	1.937 (15)	O31—Ba1^iii	2.94 (2)
Fe1—C31	1.943 (15)	O31—O41^vii	3.058 (19)
Fe1—C51	1.944 (16)	O31—H311	0.91 (4)
Fe1—C41	1.965 (15)	O31—H321	0.97 (4)
Fe2—N12	1.673 (17)	O32—O41	2.828 (18)
Fe2—C52	1.926 (15)	O32—Ba2^i	2.91 (2)
Fe2—C42	1.937 (16)	O32—O42^i	3.06 (2)
Fe2—C32	1.941 (16)	O32—H312	0.94 (4)
Fe2—C62	1.944 (15)	O32—H322	0.91 (4)
Fe2—C22	1.963 (19)	O32—H421	2.14 (3)
Fe3—N13	1.675 (16)	O33—O43	2.864 (18)
Fe3—C43	1.913 (16)	O33—Ba3^iii	2.91 (2)
Fe3—C33	1.946 (16)	O33—O44^viii	3.053 (19)
Fe3—C23	1.95 (2)	O33—H313	0.98 (4)
Fe3—C53	1.949 (16)	O33—H323	0.91 (4)
Fe3—C63	1.953 (15)	O33—H423	2.09 (3)
Fe4—N14	1.676 (16)	O34—O44^vi	2.872 (18)
Fe4—C44	1.910 (16)	O34—Ba4^i	2.93 (2)
Fe4—C34	1.931 (15)	O34—O43^ix	3.022 (19)
Fe4—C64	1.937 (16)	O34—H314	0.91 (4)
Fe4—C24	1.95 (2)	O34—H324	0.96 (4)
Fe4—C54	1.963 (16)	O41—Ba2^i	3.01 (2)
O1—N11	1.136 (18)	O41—Ba1^iv	3.03 (2)
O2—N12	1.120 (18)	O41—O31^x	3.058 (19)
O3—N13	1.149 (19)	O41—H411	1.07 (4)
O4—N14	1.113 (18)	O41—H421	0.87 (3)
N21—C21	1.185 (15)	O42—Ba1^iii	2.98 (2)
N22—C22	1.172 (15)	O42—O32^iii	3.06 (2)
N23—C23	1.168 (16)	O42—H412	1.05 (4)
N24—C24	1.170 (16)	O42—H422	0.87 (3)
N31—C31	1.179 (13)	O43—Ba3^iii	2.99 (2)
N32—C32	1.178 (14)	O43—O34^xi	3.022 (19)
N33—C33	1.190 (14)	O43—Ba4^xii	3.03 (2)
N34—C34	1.185 (14)	O43—H413	0.94 (3)
N41—C41	1.163 (14)	O43—H423	0.96 (3)
N42—C42	1.194 (14)	O44—O34^xii	2.872 (18)
N43—C43	1.200 (14)	O44—Ba4^xiii	2.99 (2)
N44—C44	1.206 (14)	O44—Ba3^ii	3.04 (2)
N51—C51	1.152 (14)	O44—O33^xiv	3.053 (19)
N52—C52	1.182 (14)	O44—H414	0.92 (4)
N53—C53	1.168 (15)	O44—H424	0.96 (4)
O21—Ba1—O31^i	125.5 (7)	Ba3—O23—H223	129 (2)
O21—Ba1—O42^i	137.8 (7)	H213—O23—H223	108 (3)
O31^i—Ba1—O42^i	57.6 (5)	Ba4—O24—H214	120.9 (19)
O21—Ba1—O41^ii	124.9 (7)	Ba4—O24—H224	129.9 (17)
O31^i—Ba1—O41^ii	61.6 (5)	H214—O24—H224	102 (2)
O42^i—Ba1—O41^ii	94.7 (6)	O42—O31—Ba1^iii	61.8 (5)
O22—Ba2—O32^iii	129.2 (7)	O42—O31—O41^vii	96.6 (6)
O22—Ba2—O41^iii	140.2 (7)	Ba1^iii—O31—O41^vii	60.6 (5)
O32^iii—Ba2—O41^iii	57.1 (4)	O42—O31—H311	113.8 (18)
O22—Ba2—O42	125.3 (6)	Ba1^iii—O31—H311	113.7 (18)
O32^iii—Ba2—O42	61.6 (5)	O41^vii—O31—H311	54.3 (16)
O41^iii—Ba2—O42	93.2 (6)	O42—O31—H321	122.1 (15)
O23—Ba3—O33^i	126.8 (7)	Ba1^iii—O31—H321	136.4 (17)
O23—Ba3—O43^i	140.0 (7)	O41^vii—O31—H321	141.2 (15)
O33^i—Ba3—O43^i	58.1 (5)	H311—O31—H321	104 (2)
O23—Ba3—O44^iv	123.8 (7)	O41—O32—Ba2^i	63.3 (5)
O33^i—Ba3—O44^iv	61.7 (5)	O41—O32—O42^i	97.0 (6)
O43^i—Ba3—O44^iv	94.4 (6)	Ba2^i—O32—O42^i	61.7 (5)
O24—Ba4—O34^iii	127.1 (7)	O41—O32—H312	114.8 (16)
O24—Ba4—O44^v	140.0 (7)	Ba2^i—O32—H312	116.2 (17)
O34^iii—Ba4—O44^v	58.1 (4)	O42^i—O32—H312	55.2 (15)
O24—Ba4—O43^vi	123.9 (6)	O41—O32—H322	123.7 (16)
O34^iii—Ba4—O43^vi	61.0 (5)	Ba2^i—O32—H322	140.2 (19)
O44^v—Ba4—O43^vi	94.1 (6)	O42^i—O32—H322	138.6 (16)
N11—Fe1—C21	176.0 (7)	H312—O32—H322	97 (2)
N11—Fe1—C61	97.4 (6)	O41—O32—H421	12.3 (7)
C21—Fe1—C61	86.5 (6)	Ba2^i—O32—H421	75.4 (8)
N11—Fe1—C31	95.0 (6)	O42^i—O32—H421	106.2 (8)
C21—Fe1—C31	85.9 (6)	H312—O32—H421	113.0 (17)
C61—Fe1—C31	87.8 (6)	H322—O32—H421	113.2 (16)
N11—Fe1—C51	95.0 (6)	O43—O33—Ba3^iii	62.4 (5)
C21—Fe1—C51	84.1 (6)	O43—O33—O44^viii	96.7 (6)
C61—Fe1—C51	90.4 (6)	Ba3^iii—O33—O44^viii	61.2 (5)
C31—Fe1—C51	170.0 (8)	O43—O33—H313	114.1 (18)
N11—Fe1—C41	94.5 (6)	Ba3^iii—O33—H313	115.3 (17)
C21—Fe1—C41	81.6 (6)	O44^viii—O33—H313	55.0 (16)
C61—Fe1—C41	168.0 (7)	O43—O33—H323	120.9 (18)
C31—Fe1—C41	89.5 (6)	Ba3^iii—O33—H323	137 (2)
C51—Fe1—C41	90.2 (6)	O44^viii—O33—H323	142.4 (18)
N12—Fe2—C52	95.0 (6)	H313—O33—H323	102 (2)
N12—Fe2—C42	95.3 (6)	O43—O33—H423	13.2 (7)
C52—Fe2—C42	91.8 (6)	Ba3^iii—O33—H423	75.3 (8)
N12—Fe2—C32	95.1 (6)	O44^viii—O33—H423	106.7 (9)
C52—Fe2—C32	169.8 (8)	H313—O33—H423	112.5 (19)
C42—Fe2—C32	88.6 (6)	H323—O33—H423	110.0 (19)
N12—Fe2—C62	96.4 (6)	O44^vi—O34—Ba4^i	62.0 (5)
C52—Fe2—C62	89.2 (6)	O44^vi—O34—O43^ix	96.7 (6)
C42—Fe2—C62	168.1 (8)	Ba4^i—O34—O43^ix	61.2 (5)
C32—Fe2—C62	88.3 (6)	O44^vi—O34—H314	112.3 (18)
N12—Fe2—C22	177.3 (7)	Ba4^i—O34—H314	116.6 (18)
C52—Fe2—C22	84.3 (6)	O43^ix—O34—H314	57.0 (16)
C42—Fe2—C22	82.1 (6)	O44^vi—O34—H324	117.5 (17)
C32—Fe2—C22	85.7 (6)	Ba4^i—O34—H324	138 (2)
C62—Fe2—C22	86.2 (6)	O43^ix—O34—H324	145.5 (17)
N13—Fe3—C43	94.9 (6)	H314—O34—H324	103 (2)
N13—Fe3—C33	95.7 (6)	O32—O41—Ba2^i	59.6 (5)
C43—Fe3—C33	90.8 (6)	O32—O41—Ba1^iv	133.5 (6)
N13—Fe3—C23	177.9 (8)	Ba2^i—O41—Ba1^iv	161.4 (7)
C43—Fe3—C23	83.2 (6)	O32—O41—O31^x	166.8 (6)
C33—Fe3—C23	85.4 (6)	Ba2^i—O41—O31^x	107.7 (5)
N13—Fe3—C53	95.8 (7)	Ba1^iv—O41—O31^x	57.8 (4)
C43—Fe3—C53	90.7 (7)	O32—O41—H411	106.4 (15)
C33—Fe3—C53	168.2 (7)	Ba2^i—O41—H411	107.7 (16)
C23—Fe3—C53	83.2 (6)	Ba1^iv—O41—H411	82.6 (16)
N13—Fe3—C63	94.8 (6)	O31^x—O41—H411	80.0 (15)
C43—Fe3—C63	170.3 (8)	O32—O41—H421	31.5 (15)
C33—Fe3—C63	87.8 (6)	Ba2^i—O41—H421	90.5 (16)
C23—Fe3—C63	87.1 (6)	Ba1^iv—O41—H421	102.0 (16)
C53—Fe3—C63	88.8 (6)	O31^x—O41—H421	159.0 (16)
N14—Fe4—C44	94.7 (7)	H411—O41—H421	105 (2)
N14—Fe4—C34	96.3 (6)	O31—O42—Ba1^iii	60.6 (5)
C44—Fe4—C34	90.2 (6)	O31—O42—O32^iii	167.9 (6)
N14—Fe4—C64	95.7 (6)	Ba1^iii—O42—O32^iii	107.9 (6)
C44—Fe4—C64	169.6 (8)	O31—O42—Ba2	133.8 (6)
C34—Fe4—C64	88.3 (6)	Ba1^iii—O42—Ba2	162.2 (6)
N14—Fe4—C24	177.3 (8)	O32^iii—O42—Ba2	56.7 (5)
C44—Fe4—C24	83.1 (6)	O31—O42—H412	107.0 (15)
C34—Fe4—C24	85.2 (6)	Ba1^iii—O42—H412	107.7 (16)
C64—Fe4—C24	86.5 (6)	O32^iii—O42—H412	79.2 (15)
N14—Fe4—C54	95.8 (6)	Ba2—O42—H412	79.8 (16)
C44—Fe4—C54	91.1 (7)	O31—O42—H422	32.6 (15)
C34—Fe4—C54	167.6 (8)	Ba1^iii—O42—H422	92.5 (17)
C64—Fe4—C54	88.3 (6)	O32^iii—O42—H422	157.0 (17)
C24—Fe4—C54	82.7 (6)	Ba2—O42—H422	101.2 (16)
O1—N11—Fe1	179.2 (12)	H412—O42—H422	105 (2)
O2—N12—Fe2	177.3 (13)	O33—O43—Ba3^iii	59.5 (5)
O3—N13—Fe3	175.7 (13)	O33—O43—O34^xi	167.0 (6)
O4—N14—Fe4	178.9 (13)	Ba3^iii—O43—O34^xi	108.8 (5)
N21—C21—Fe1	177.6 (10)	O33—O43—Ba4^xii	131.8 (6)
N22—C22—Fe2	177.6 (11)	Ba3^iii—O43—Ba4^xii	161.8 (6)
N23—C23—Fe3	177.1 (11)	O34^xi—O43—Ba4^xii	57.9 (5)
N24—C24—Fe4	177.2 (11)	O33—O43—H413	104.0 (15)
N31—C31—Fe1	177.1 (10)	Ba3^iii—O43—H413	108.7 (16)
N32—C32—Fe2	177.4 (10)	O34^xi—O43—H413	84.7 (15)
N33—C33—Fe3	178.7 (11)	Ba4^xii—O43—H413	83.6 (16)
N34—C34—Fe4	178.6 (11)	O33—O43—H423	29.9 (15)
N41—C41—Fe1	176.6 (10)	Ba3^iii—O43—H423	88.8 (17)
N42—C42—Fe2	177.7 (11)	O34^xi—O43—H423	158.4 (16)
N43—C43—Fe3	174.4 (12)	Ba4^xii—O43—H423	101.9 (16)
N44—C44—Fe4	176.3 (11)	H413—O43—H423	102 (2)
N51—C51—Fe1	177.6 (12)	O34^xii—O44—Ba4^xiii	59.9 (5)
N52—C52—Fe2	176.1 (11)	O34^xii—O44—Ba3^ii	132.6 (6)
N53—C53—Fe3	177.7 (12)	Ba4^xiii—O44—Ba3^ii	161.4 (7)
N54—C54—Fe4	178.0 (11)	O34^xii—O44—O33^xiv	167.1 (6)
N61—C61—Fe1	178.5 (11)	Ba4^xiii—O44—O33^xiv	108.6 (5)
N62—C62—Fe2	178.2 (11)	Ba3^ii—O44—O33^xiv	57.0 (4)
N63—C63—Fe3	178.6 (11)	O34^xii—O44—H414	31.3 (16)
N64—C64—Fe4	177.7 (11)	Ba4^xiii—O44—H414	90.7 (17)
Ba1—O21—H211	123 (2)	Ba3^ii—O44—H414	101.5 (16)
Ba1—O21—H221	122.7 (18)	O33^xiv—O44—H414	157.5 (16)
H211—O21—H221	111 (3)	O34^xii—O44—H424	104.8 (14)
Ba2—O22—H212	120.6 (17)	Ba4^xiii—O44—H424	107.6 (15)
Ba2—O22—H222	127 (2)	Ba3^ii—O44—H424	83.7 (15)
H212—O22—H222	104 (3)	O33^xiv—O44—H424	83.6 (15)
Ba3—O23—H213	118.7 (19)	H414—O44—H424	102 (2)

Symmetry codes: (i) x, y+1, z; (ii) x, y, z−1; (iii) x, y−1, z; (iv) x, y, z+1; (v) x+1, y−1, z; (vi) x+1, y, z; (vii) x, y−1, z−1; (viii) x, y−1, z+1; (ix) x+1, y+1, z; (x) x, y+1, z+1; (xi) x−1, y−1, z; (xii) x−1, y, z; (xiii) x−1, y+1, z; (xiv) x, y+1, z−1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O21—H211···N44^i	0.87 (3)	2.63 (3)	3.46 (2)	160 (3)
O21—H221···N54^i	0.98 (3)	2.65 (3)	3.37 (2)	130 (2)
O21—H221···N64	0.98 (3)	2.62 (3)	3.49 (2)	148 (2)
O22—H212···N43^iii	1.03 (4)	2.53 (3)	3.52 (2)	163 (3)
O22—H222···N53^iii	0.92 (4)	2.66 (3)	3.39 (2)	137 (3)
O22—H222···N63	0.92 (4)	2.69 (3)	3.48 (2)	144 (3)
O23—H213···N42^i	0.92 (4)	2.45 (3)	3.33 (2)	161 (3)
O23—H223···N62	0.90 (4)	2.62 (3)	3.42 (2)	148 (3)
O24—H214···N41^iii	1.03 (4)	2.41 (3)	3.41 (2)	161 (3)
O24—H224···N61	1.03 (4)	2.57 (3)	3.45 (2)	143 (3)
O31—H311···N61	0.91 (4)	2.52 (3)	3.37 (2)	155 (3)
O31—H321···N21	0.97 (4)	2.23 (3)	3.12 (2)	153 (3)
O31—H321···O4	0.97 (4)	3.12 (3)	3.61 (2)	113 (3)
O32—H312···N62	0.94 (4)	2.52 (3)	3.40 (2)	155 (3)
O32—H322···N22	0.91 (4)	2.31 (3)	3.17 (2)	160 (3)
O32—H322···O3	0.91 (4)	3.14 (4)	3.54 (3)	110 (3)
O33—H313···N33^xii	0.98 (4)	2.48 (3)	3.40 (2)	156 (3)
O33—H323···N23^xii	0.91 (4)	2.28 (3)	3.14 (2)	156 (3)
O33—H323···O2	0.91 (4)	3.14 (3)	3.58 (2)	112 (3)
O34—H314···N34^vi	0.91 (3)	2.53 (3)	3.39 (2)	159 (3)
O34—H324···N24^vi	0.96 (4)	2.23 (3)	3.14 (2)	157 (3)
O34—H324···O1	0.96 (4)	3.14 (4)	3.57 (3)	109 (2)
O41—H411···N42^i	1.07 (4)	2.12 (3)	3.05 (2)	142 (3)
O41—H421···O32	0.87 (3)	2.14 (3)	2.83 (2)	136 (3)
O42—H412···N41^iii	1.05 (3)	2.12 (3)	3.03 (2)	145 (3)
O42—H422···O31	0.87 (3)	2.17 (3)	2.85 (2)	135 (3)
O43—H413···N53^xi	0.94 (3)	2.18 (3)	2.97 (2)	143 (3)
O43—H423···O33	0.96 (3)	2.09 (3)	2.86 (2)	137 (3)
O44—H414···O34^xii	0.92 (3)	2.14 (3)	2.87 (2)	136 (3)
O44—H424···N54^i	0.96 (3)	2.18 (3)	3.00 (2)	142 (3)

Symmetry codes: (i) x, y+1, z; (iii) x, y−1, z; (vi) x+1, y, z; (xi) x−1, y−1, z; (xii) x−1, y, z.