Crystal structure of [Y6(μ6-O)(μ3-OH)8(H2O)24]I8·8H2O.

The crystal structure of the title compound {systematic name: octa-μ3-hydroxido-μ6-oxido-hexa-kis-[tetra-aqua-yttrium(III)] octa-iodide octa-hydrate}, is characterized by the presence of the centrosymmetric mol-ecular entity [Y6(μ6-O)(μ3-OH)8(H2O)24](8+), in which the six Y(3+) cations are arranged octa-hedrally around a μ6-O atom at the centre of the cationic complex. Each of the eight faces of the Y6 octa-hedron is capped by an μ3-OH group in the form of a distorted cube. In the hexa-nuclear entity, the Y(3+) cations are coordinated by the central μ6-O atom, the O atoms of four μ3-OH and of four water mol-ecules. The resulting coordination sphere of the metal ions is a capped square-anti-prism. The crystal packing is quite similar to that of the ortho-rhom-bic [Ln 6(μ6-O)(μ3-OH)8(H2O)24]I8·8H2O structures with Ln = La-Nd, Eu-Tb, Dy, except that the title compound exhibits a slight monoclinic distortion. The proximity of the cationic complexes and the lattice water mol-ecules leads to the formation of a three-dimensional hydrogen-bonded network of medium strength.

Chemical context

Rare-earth-based oxido-hydroxido polynuclear complexes are of inter­est because of their unique luminescence (Chen et al., 2010 ▶; Le Natur et al., 2013 ▶; Petit et al., 2009 ▶), magnetic properties (Abbas et al., 2010 ▶; Xu et al., 2011 ▶) or structural characteristics (Zheng, 2001 ▶; Andrews et al., 2013 ▶). Actually, in this kind of complex, the spatial proximity between metal ions affords cooperative/synergetic effects or energy-transfer mechanisms workable in terms of optical properties. For more than a decade, our group has been involved in the synthesis and the characterization of such rare-earth-based hexa­nuclear complexes (Calvez et al., 2010 ▶). The hexa­nuclear complexes crystallize in different structures depending on the counter-anion (e.g. nitrate, perchlorate, iodide: Zak et al., 1994 ▶; Wang et al., 2000 ▶; Mudring et al., 2006 ▶), the number of lattice water mol­ecules and/or the radius of the involved lanthanide ion. Since the pioneering work of Zak et al. (1994 ▶), we have developed a systematic synthetic procedure for the nitrate counter-anion complex with most of the rare earth elements (Calvez et al., 2008 ▶, 2010 ▶). In this context, we have undertaken the study of a series of complexes based on the iodide counter-anion which have never been obtained with heavier rare earth ions. We report here the synthesis and crystal structure of the yttrium derivative.

Structural commentary

In contrast to the ortho­rhom­bic [Ln 6(μ6-O)(μ3-OH)8(H2O)24]I8·8H2O structures with Ln = La—Nd, Eu—Tb, Dy (Mudring & Babai, 2005 ▶; Mudring et al., 2006 ▶; Rukk et al., 2009 ▶), the crystal structure of the yttrium member of this series has monoclinic symmetry, with the monoclinic angle close to 90° (Table 2 ▶). The asymmetric unit of [Y6(μ6-O)(μ3-OH)8(H2O)24]I8·8H2O contains half of the formula unit because the complete complex is situated on a centre of inversion. Three independent yttrium cations (Y1, Y2 and Y3), four oxygen atoms from μ3-hydroxyl groups (O1, O2, O3, O4), twelve oxygen atoms of terminal aqua ligands coordin­ating to each yttrium cation (Y1: O5, O6, O7, O8; Y2: O9, O10, O11, O12; Y3: O13, O14, O15 O16), one μ6-bridging O atom (O) lying on an inversion centre, four iodide anions (I1, I2, I3, I4) and four oxygen atoms of lattice water mol­ecules (OW1, OW2, OW3, OW4) are present in the crystal structure (Fig. 1 ▶). Calculations with the SHAPE software suite (Alvarez et al., 2005 ▶) indicate that each of the coordination polyhedra surrounding the Y3+ ions is best described as a spherical capped square-anti­prism (Ruiz-Martínez et al., 2010 ▶) with idealized C 4 symmetry. However, the true symmetry of this structural fragment in the title structure is C 1.

Table 2

Experimental details

Crystal data
Chemical formula	[Y6O(OH)8(H2O)24]I88H2O
M r	2277.24
Crystal system, space group	Monoclinic, P21/n
Temperature (K)	293
a, b, c ()	12.9099(2), 14.8050(2), 14.7933(3)
()	90.821(1)
V (3)	2827.17(8)
Z	2
Radiation type	Mo K
(mm1)	10.54
Crystal size (mm)	0.18 0.14 0.1
Data collection
Diffractometer	Nonius KappaCCD
Absorption correction	Gaussian (Coppens et al., 1965 ▶)
T min, T max	0.018, 0.091
No. of measured, independent and observed [I > 2(I)] reflections	35352, 6374, 5449
R int	0.124
(sin /)max (1)	0.647
Refinement
R[F 2 > 2(F 2)], wR(F 2), S	0.067, 0.178, 1.11
No. of reflections	6374
No. of parameters	251
	w = 1/[2(F o 2) + (0.0487P)2 + 43.8859P] where P = (F o 2 + 2F c 2)/3
max, min (e 3)	2.62, 1.83

Computer programs: COLLECT (Nonius, 1998 ▶), EVALCCD (Duisenberg et al., 2003 ▶), SHELXS97 and SHELXL97 (Sheldrick, 2008 ▶), DIAMOND (Brandenburg, 2006 ▶) and publCIF (Westrip, 2010 ▶).

Figure 1

The asymmetric unit of the title complex. Displacement ellipsoids are drawn at the 50% probability level.

Since the μ6-O atom is located on an inversion centre and binds to six Y3+ cations, a slightly distorted anion-centred [OY6] octa­hedron results (Fig. 2 ▶). The average of the Y⋯Y distances between adjacent cations in the octa­hedron is found to be 3.536 Å. The mean Y—(μ6-O) distance is 2.537 Å, while the averaged Y—(μ3-OH) is 2.34 Å. The hydroxide ions are situated above the eight faces of the OY6 octa­hedron and form a distorted cube around the octa­hedron (Fig. 2 ▶).

Figure 2

The OY6 octa­hedron in the complex [Y6(μ6-O)(μ3-OH)8(H2O)24]8+ cation. Y atoms are green and O atoms are red.

Supra­molecular features

The hexa­nuclear [Y6(μ6-O)(μ3-OH)8(H2O)24]8+ units are arranged in a body-centred fashion in the crystal structure. Each of these units is surrounded by twelve iodide anions, connecting the units to each other through Coulombic inter­actions. Although the hydrogen atoms of the water mol­ecules and hydroxide groups could not be located, the range of O⋯O distances between the cationic complex and the lattice water mol­ecules suggest the formation of medium-strength hydrogen bonds (Table 1 ▶). These inter­actions lead to the formation of a three-dimensional network in the structure (Fig. 3 ▶).

Table 1

Hydrogen-bond geometry ()

D A	D A
O7OW2	2.646(4)
O10OW3	2.764(1)
O13OW4	2.803(8)
O15OW1	2.767(2)
O16OW4	2.836(2)
O16OW1	2.851(6)

Figure 3

The crystal structure of [Y6(μ6-O)(μ3-OH)8(H2O)24]I8·8H2O in projections along [100], [010] and [001], respectively, from left to right. Y atoms are green, O atoms are red and I atoms are yellow.

Synthesis and crystallization

Yttrium oxide Y2O3 (2 g, Strem Chemicals 4M) was dissolved in fresh hydro­iodic acid (9 ml, 57wt%, unstabilized from Acros Organics) under gentle heating (323 K). If the acid used is not fresh, it should be distilled twice. The clear solution was exposed to air under isothermal conditions (6 weeks). At this stage, the pH of the solution remains acidic. Large pale-yellow polyhedral crystals were separated manually from the solution and were mounted into a glass capillary.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▶. The hydrogen atoms from the water mol­ecules or hydroxide could not be assigned reliably and thus were not included in the refinement. However, they were taken into account for the chemical formula sum, moiety, weight, as well as for the absorption coefficient and the number of electrons in the unit cell.

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536814025434/wm5083sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814025434/wm5083Isup2.hkl

CCDC reference: 1035218

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Y6O(OH)8(H2O)24]I8·8H2O	F(000) = 2116
Mr = 2277.24	Dx = 2.675 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 62388 reflections
a = 12.9099 (2) Å	θ = 2.9–27.5°
b = 14.8050 (2) Å	µ = 10.54 mm−1
c = 14.7933 (3) Å	T = 293 K
β = 90.821 (1)°	Block, colorless
V = 2827.17 (8) Å3	0.18 × 0.14 × 0.1 mm
Z = 2

Nonius KappaCCD diffractometer	6374 independent reflections
Radiation source: fine-focus sealed tube	5449 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.124
CCD rotation images, thick slices scans	θmax = 27.4°, θmin = 3.1°
Absorption correction: gaussian (Coppens et al., 1965)	h = −16→16
Tmin = 0.018, Tmax = 0.091	k = −19→18
35352 measured reflections	l = −19→19

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)] = 0.067	w = 1/[σ2(Fo2) + (0.0487P)2 + 43.8859P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.178	(Δ/σ)max = 0.001
S = 1.11	Δρmax = 2.62 e Å−3
6374 reflections	Δρmin = −1.83 e Å−3
251 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraints	Extinction coefficient: 0.00258 (19)

Experimental. 6336 sampling points

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.

	x	y	z	Uiso*/Ueq
Y1	0.50083 (7)	1.00150 (6)	1.16560 (6)	0.0335 (2)
Y2	0.46090 (7)	1.16586 (6)	0.99794 (6)	0.0317 (2)
Y3	0.30677 (7)	0.96613 (6)	0.99944 (6)	0.0323 (2)
I1	0.49148 (9)	0.82346 (8)	0.49868 (6)	0.0707 (3)
I2	0.28137 (7)	0.72379 (7)	0.24171 (7)	0.0650 (3)
I3	0.48625 (14)	0.50289 (7)	0.14980 (8)	0.0932 (4)
I4	0.78359 (8)	0.78678 (8)	0.26729 (8)	0.0792 (4)
O	0.5000	1.0000	1.0000	0.0293 (17)
O1	0.3633 (5)	1.0806 (4)	1.0999 (4)	0.0328 (13)
O2	0.4097 (5)	0.8826 (4)	1.1002 (4)	0.0313 (13)
O3	0.3622 (5)	1.0773 (4)	0.8978 (4)	0.0321 (13)
O4	0.4081 (5)	0.8803 (4)	0.9008 (4)	0.0335 (13)
O5	0.6563 (13)	1.0251 (17)	1.2721 (11)	0.150 (8)
O6	0.5306 (14)	0.8859 (13)	1.2758 (10)	0.136 (7)
O7	0.3511 (12)	0.9672 (11)	1.2711 (9)	0.106 (5)
O8	0.4775 (9)	1.1210 (7)	1.2708 (6)	0.069 (3)
O9	0.4402 (8)	1.2676 (6)	1.1305 (7)	0.064 (2)
O10	0.2918 (7)	1.2392 (6)	0.9958 (7)	0.065 (2)
O11	0.4402 (7)	1.2644 (6)	0.8649 (7)	0.060 (2)
O12	0.5819 (8)	1.2981 (6)	0.9988 (7)	0.066 (2)
O13	0.1968 (6)	0.9524 (7)	1.1339 (6)	0.058 (2)
O14	0.2216 (8)	0.8163 (7)	1.0027 (8)	0.075 (3)
O15	0.1950 (6)	0.9452 (7)	0.8664 (6)	0.059 (2)
O16	0.1578 (7)	1.0700 (7)	0.9987 (7)	0.063 (2)
OW1	−0.0079 (7)	0.8851 (8)	0.8689 (7)	0.070 (3)
OW2	0.2083 (19)	0.5431 (17)	0.0762 (13)	0.164 (8)
OW3	0.7261 (18)	0.5806 (14)	0.051 (2)	0.216 (13)
OW4	0.9948 (7)	0.8828 (8)	0.1328 (7)	0.069 (3)

	U11	U22	U33	U12	U13	U23
Y1	0.0380 (5)	0.0307 (5)	0.0318 (4)	0.0014 (3)	−0.0006 (3)	0.0000 (3)
Y2	0.0313 (4)	0.0271 (4)	0.0367 (5)	−0.0001 (3)	−0.0010 (3)	0.0003 (3)
Y3	0.0297 (4)	0.0292 (4)	0.0381 (5)	−0.0001 (3)	−0.0011 (3)	0.0003 (3)
I1	0.0799 (7)	0.0740 (7)	0.0580 (5)	0.0010 (5)	−0.0028 (4)	−0.0014 (4)
I2	0.0624 (5)	0.0599 (5)	0.0731 (6)	−0.0069 (4)	0.0146 (4)	0.0202 (4)
I3	0.1624 (13)	0.0473 (5)	0.0701 (7)	−0.0080 (6)	0.0074 (7)	0.0003 (4)
I4	0.0647 (6)	0.0771 (7)	0.0950 (8)	0.0062 (5)	−0.0237 (5)	0.0377 (6)
O	0.035 (4)	0.021 (4)	0.032 (4)	0.001 (3)	−0.002 (3)	0.002 (3)
O1	0.032 (3)	0.028 (3)	0.039 (3)	−0.001 (2)	0.001 (3)	−0.003 (3)
O2	0.029 (3)	0.023 (3)	0.042 (3)	0.001 (2)	0.000 (3)	0.005 (3)
O3	0.029 (3)	0.033 (3)	0.034 (3)	−0.002 (2)	−0.003 (2)	0.003 (3)
O4	0.029 (3)	0.033 (3)	0.038 (3)	0.000 (2)	−0.006 (3)	0.000 (3)
O5	0.099 (11)	0.26 (3)	0.090 (11)	0.009 (13)	−0.001 (9)	−0.023 (13)
O6	0.157 (15)	0.171 (17)	0.080 (9)	0.027 (12)	0.002 (9)	0.065 (10)
O7	0.127 (11)	0.120 (11)	0.070 (7)	−0.043 (9)	0.026 (7)	−0.005 (7)
O8	0.101 (8)	0.057 (6)	0.050 (5)	0.002 (5)	0.000 (5)	−0.018 (4)
O9	0.064 (6)	0.051 (5)	0.078 (6)	−0.003 (4)	0.004 (5)	−0.020 (5)
O10	0.054 (5)	0.052 (5)	0.089 (7)	0.018 (4)	−0.004 (5)	0.006 (5)
O11	0.058 (5)	0.047 (5)	0.075 (6)	0.001 (4)	−0.006 (4)	0.020 (4)
O12	0.067 (6)	0.048 (5)	0.082 (7)	−0.007 (4)	−0.004 (5)	0.007 (5)
O13	0.041 (4)	0.073 (6)	0.061 (5)	0.000 (4)	0.005 (4)	0.010 (4)
O14	0.062 (6)	0.065 (6)	0.098 (8)	−0.027 (5)	−0.003 (5)	0.002 (6)
O15	0.045 (4)	0.075 (6)	0.058 (5)	−0.004 (4)	−0.018 (4)	−0.005 (4)
O16	0.041 (4)	0.079 (6)	0.071 (6)	0.023 (4)	0.002 (4)	−0.006 (5)
OW1	0.051 (5)	0.086 (7)	0.072 (6)	−0.006 (5)	−0.004 (4)	−0.009 (5)
OW2	0.19 (2)	0.19 (2)	0.114 (14)	0.012 (17)	0.028 (13)	−0.005 (14)
OW3	0.158 (19)	0.091 (13)	0.40 (4)	0.027 (13)	0.09 (2)	0.004 (19)
OW4	0.052 (5)	0.086 (7)	0.068 (6)	−0.010 (5)	−0.006 (4)	0.010 (5)

Y1—O2	2.321 (6)	Y2—O11	2.462 (9)
Y1—O3i	2.326 (6)	Y2—O9	2.490 (9)
Y1—O1	2.328 (7)	Y2—O12	2.506 (9)
Y1—O4i	2.332 (7)	Y2—O	2.5070 (9)
Y1—O8	2.378 (9)	Y3—O2	2.336 (6)
Y1—O6	2.390 (14)	Y3—O3	2.347 (6)
Y1—O	2.4497 (9)	Y3—O4	2.348 (7)
Y1—O7	2.553 (13)	Y3—O1	2.362 (6)
Y1—O5	2.557 (18)	Y3—O15	2.443 (8)
Y2—O2i	2.341 (6)	Y3—O16	2.462 (8)
Y2—O3	2.341 (6)	Y3—O13	2.469 (8)
Y2—O4i	2.344 (6)	Y3—O14	2.477 (10)
Y2—O1	2.347 (6)	Y3—O	2.5444 (9)
Y2—O10	2.438 (9)
O2—Y1—O3i	80.5 (2)	O10—Y2—O	128.0 (2)
O2—Y1—O1	80.1 (2)	O11—Y2—O	127.6 (2)
O3i—Y1—O1	131.5 (2)	O9—Y2—O	127.3 (3)
O2—Y1—O4i	130.4 (2)	O12—Y2—O	129.8 (2)
O3i—Y1—O4i	79.4 (2)	O2—Y3—O3	127.1 (2)
O1—Y1—O4i	80.4 (2)	O2—Y3—O4	78.1 (2)
O2—Y1—O8	140.2 (3)	O3—Y3—O4	78.7 (2)
O3i—Y1—O8	137.8 (3)	O2—Y3—O1	79.1 (2)
O1—Y1—O8	78.2 (3)	O3—Y3—O1	78.8 (2)
O4i—Y1—O8	77.7 (3)	O4—Y3—O1	127.5 (2)
O2—Y1—O6	79.4 (5)	O2—Y3—O15	140.4 (3)
O3i—Y1—O6	78.5 (5)	O3—Y3—O15	75.8 (3)
O1—Y1—O6	139.4 (5)	O4—Y3—O15	76.0 (3)
O4i—Y1—O6	138.4 (5)	O1—Y3—O15	140.5 (3)
O8—Y1—O6	96.2 (6)	O2—Y3—O16	140.4 (3)
O2—Y1—O	65.23 (16)	O3—Y3—O16	78.7 (3)
O3i—Y1—O	65.46 (16)	O4—Y3—O16	141.0 (3)
O1—Y1—O	66.07 (16)	O1—Y3—O16	77.8 (3)
O4i—Y1—O	65.21 (16)	O15—Y3—O16	67.9 (3)
O8—Y1—O	131.5 (3)	O2—Y3—O13	76.8 (3)
O6—Y1—O	132.4 (5)	O3—Y3—O13	139.3 (3)
O2—Y1—O7	73.7 (4)	O4—Y3—O13	142.0 (3)
O3i—Y1—O7	137.2 (4)	O1—Y3—O13	74.2 (3)
O1—Y1—O7	77.0 (4)	O15—Y3—O13	107.4 (3)
O4i—Y1—O7	142.9 (4)	O16—Y3—O13	66.2 (3)
O8—Y1—O7	69.2 (4)	O2—Y3—O14	76.3 (3)
O6—Y1—O7	63.7 (6)	O3—Y3—O14	141.2 (3)
O—Y1—O7	128.1 (3)	O4—Y3—O14	77.2 (3)
O2—Y1—O5	138.5 (6)	O1—Y3—O14	139.8 (3)
O3i—Y1—O5	73.9 (4)	O15—Y3—O14	69.2 (4)
O1—Y1—O5	140.9 (6)	O16—Y3—O14	102.3 (4)
O4i—Y1—O5	76.2 (5)	O13—Y3—O14	69.5 (4)
O8—Y1—O5	66.5 (5)	O2—Y3—O	63.48 (15)
O6—Y1—O5	64.0 (7)	O3—Y3—O	63.63 (15)
O—Y1—O5	127.5 (4)	O4—Y3—O	63.47 (15)
O7—Y1—O5	104.2 (5)	O1—Y3—O	64.06 (15)
O2i—Y2—O3	79.8 (2)	O15—Y3—O	126.5 (2)
O2i—Y2—O4i	78.0 (2)	O16—Y3—O	130.0 (3)
O3—Y2—O4i	128.4 (2)	O13—Y3—O	126.1 (2)
O2i—Y2—O1	128.9 (2)	O14—Y3—O	127.7 (3)
O3—Y2—O1	79.2 (2)	Y1i—O—Y1	180.0
O4i—Y2—O1	79.7 (2)	Y1i—O—Y2i	90.07 (3)
O2i—Y2—O10	140.8 (3)	Y1—O—Y2i	89.93 (3)
O3—Y2—O10	76.2 (3)	Y1i—O—Y2	89.93 (3)
O4i—Y2—O10	140.9 (3)	Y1—O—Y2	90.07 (3)
O1—Y2—O10	76.1 (3)	Y2i—O—Y2	180.0
O2i—Y2—O11	75.9 (3)	Y1i—O—Y3i	89.73 (3)
O3—Y2—O11	77.0 (3)	Y1—O—Y3i	90.27 (3)
O4i—Y2—O11	138.8 (3)	Y2i—O—Y3i	89.76 (3)
O1—Y2—O11	141.2 (3)	Y2—O—Y3i	90.24 (3)
O10—Y2—O11	68.8 (3)	Y1i—O—Y3	90.27 (3)
O2i—Y2—O9	139.4 (3)	Y1—O—Y3	89.73 (3)
O3—Y2—O9	140.6 (3)	Y2i—O—Y3	90.24 (3)
O4i—Y2—O9	76.0 (3)	Y2—O—Y3	89.76 (3)
O1—Y2—O9	75.8 (3)	Y3i—O—Y3	180.0
O10—Y2—O9	68.6 (3)	Y1—O1—Y2	97.2 (2)
O11—Y2—O9	105.1 (4)	Y1—O1—Y3	97.4 (2)
O2i—Y2—O12	78.0 (3)	Y2—O1—Y3	98.4 (2)
O3—Y2—O12	140.8 (3)	Y1—O2—Y3	98.3 (2)
O4i—Y2—O12	77.3 (3)	Y1—O2—Y2i	97.4 (2)
O1—Y2—O12	139.3 (3)	Y3—O2—Y2i	99.9 (2)
O10—Y2—O12	102.2 (3)	Y1i—O3—Y2	97.3 (2)
O11—Y2—O12	66.5 (3)	Y1i—O3—Y3	98.5 (2)
O9—Y2—O12	66.3 (3)	Y2—O3—Y3	99.0 (2)
O2i—Y2—O	64.02 (15)	Y1i—O4—Y2i	97.2 (2)
O3—Y2—O	64.31 (16)	Y1i—O4—Y3	98.3 (2)
O4i—Y2—O	64.12 (16)	Y2i—O4—Y3	99.4 (2)
O1—Y2—O	64.86 (16)

D—H···A	D···A
O7···OW2	2.646 (4)
O10···OW3	2.764 (1)
O13···OW4	2.803 (8)
O15···OW1	2.767 (2)
O16···OW4	2.836 (2)
O16···OW1	2.851 (6)