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During an investigation of the SrO-CuO-P2O5-H2O system, single crystals of distrontium hexa­hydroxido­cuprate(II), Sr2[Cu(OH)6], were obtained by the hydro­thermal method. The blue prismatic crystals of Sr2[Cu(OH)6] adopt the same structure type as Ba2[Cu(OH)6], Sr2[Zn(OH)6] and Ba2[Zn(OH)6]. The Cu atoms, located at (0, 0, 1\over2) (site symmetry \overline{1}), form mutually isolated and highly elongated Cu(OH)6 octa­hedra, which are inter­connected to slightly distorted Sr(OH)6 trigonal prisms, forming a layered structure. The location of H atoms from difference Fourier maps and their refinement allowed the precise determination of a three-dimensional hydrogen-bonding network in which all hy­drox­ide O atoms are involved. In addition, the hydrogen-bonding topologies in Sr2[Cu(OH)6] and other similar hexa­hydroxido­metallates with the general formulae M1[M2(OH)6], M12[M2(OH)6] and M13[M2(OH)6] were analysed in detail.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109021519/sq3197sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270109021519/sq3197Isup2.hkl
Contains datablock I

Comment top

This work is a part of our ongoing investigations regarding tetrahedral–octahedral framework structures with potentially interesting properties (Đorđević et al., 2008; Đorđević & Karanović, 2008; Stojanović et al., 2008). The aim of the current study was the synthesis and characterization of new compounds in the insufficiently known SrO–CuO–P2O5–H2O system. The hydrothermal synthesis and crystal structure of distrontium hexahydroxidocuprate(II), Sr2[Cu(OH)6], are reported here.

Sr2[Cu(OH)6] belongs to a small family of inorganic compounds having the same structure type and general formula M12[M2(OH)6] (M1 = Ba2+ and Sr2+, and M2 = Cu2+ and Zn2+). All compounds crystallize in the space group P21/c (No. 14) with Z = 2, but they were described in different settings. A study by Dubler et al. (1973) reported the space group as P21/c (unique axis b) for both Ba2[Cu(OH)6] and Sr2[Cu(OH)6]. The crystal structure of Sr2[Cu(OH)6] was investigated later (Nadezhina et al., 1980a,b) in the same space group, but in the P21/b setting (unique axis c). The analogous Zn compounds, Sr2[Zn(OH)6] and Ba2[Zn(OH)6], were described in P21/n (Stahl & Jacobs, 1998), and they have the same features as our data. In the present study, the previously reported structural model was confirmed, although with much improved precision for the atomic coordinates and interatomic distances. In addition, the first reliable location of H atoms allowed detailed insight into the network of hydrogen bonds.

The Cu atom, situated at an inversion centre (special position 2b in P21/n), is coordinated by four closer O atoms (two O1 and two O2) and two O3 atoms at much longer distances (Fig. 1 and Table 1), forming very elongated Cu(OH)6 octahedra that are isolated from one another. The six nearest O atoms (two symmetry equivalents of O1, O2 and O3) define a somewhat distorted trigonal–prismatic geometry around the Sr ions, which are displaced toward the one of the bases. Each Sr(OH)6 prism shares two edges from its basal plane with two neighboring prisms, forming zigzag chains parallel to the [010] direction. The remaining two O atoms bridge the chains, producing slightly corrugated layers of the `lying' [clarify meaning] Sr prisms parallel to (110). In this way the whole structure contains alternate layers of Sr and Cu polyhedra (Fig. 2). Alternatively, if the second-sphere Sr neighbors are accounted for, the Sr coordination can be described as a distorted tricapped trigonal prism (Fig. 1), similar to that found for the M1 site in the apatite structure (Đorđević et al., 2008). Three capping O atoms (O1, O2 and O3) at longer distances are located near the equatorial plane of the trigonal prism. The longest of them is the Sr1—O1vi bond distance [3.384 (3) Å; symmetry code: (vi) x - 1, y, z] and it contributes to the bond-valence sum by only 3.3%.

As expected, H atoms fill the spaces between Sr and Cu polyhedra. Both the O1/H1 and O2/H2 groups are hydrogen bonded to O3 atoms [O3vii and O3viii, respectively; symmetry codes: (vii) x + 1/2, -y + 1/2, z - 1/2; (viii) -x + 1/2, y - 1/2, -z + 1/2], while the O3/H3 group is hydrogen bonded atom O1ii [symmetry code: (ii) -x + 3/2, y + 1/2, -z + 1/2; Table 2].

Considering the contribution of non-H atoms only, the bond-valence calculation (Wills, 2009) is satisfied by the described geometry: Σνij(Sr1) = 2.01 valence units (v.u.) for coordination number (CN) = 9 (and 1.70 v.u. for CN = 6), Σνij(Cu1) = 2.00 v.u. for CN = 6 (1.84 v.u. for CN = 4), Σνij(O1) = 1.09 v.u., Σνij(O2) = 1.10 v.u. and Σνij(O3) = 0.82 v.u. The bond-valence calculations show that the Sr—O and Cu—O bond lengths are consistent with the presence of divalent strontium and divalent copper. As expected, the bond-valence sums for the O atoms are undersaturated. Taking into account that all O atoms act as single hydrogen-bond donors and atom O1 acts as a single hydrogen-bond acceptor, while atom O3 is a double hydrogen-bond acceptor, the bond valences are well balanced (Brown, 1992; Wills, 2009). The fact that the bond valences for atoms O1 and O2 are the same indicates that O2 could also be a single hydrogen-bond acceptor. This could be explained by a possible different orientation of atom H3, which would be associated with two acceptors, O1 and O2. Nevertheless, the two O···O distances are different: O3···O1ii [3.048 (5) Å; symmetry code: (ii) -x + 3/2, y + 1/2, -z + 1/2] is shorter than O3···O2i [3.128 (5) Å; symmetry code: (i) -x + 1,-y, -z + 1], and in the structure refinement it was assumed that the hydroxy group O3/H3 was completely in one orientation.

Between every two Cu(OH)6 octahedra from the same layer there are two O2—H2···O3 bonds, forming eight-membered pseudo-rings and pseudo-chains of Cu octahedra parallel to [100]. The Cu···Cu distance along the pseudo-chain extension is shorter [5.7924 (4) Å] than that perpendicular to it [6.1663 (4) Å]. The other two pairs of hydrogen bonds, O1—H1···O3 and O3—H3···O1, form additional eight-membered pseudo-rings around an empty site at (0, 0, 0) (special position 2a in P21/n), linking Cu(OH)6 octahedra from different layers so an infinite three-dimensional network of hydrogen bonds exists.

Although the H-atom positions and O—H distances were mostly unrealistic, a similar network of three hydrogen bonds connecting the Zn(OH)6 octahedra was observed in Sr2[Zn(OH)6] and Ba2[Zn(OH)6] (Stahl & Jacobs, 1998). The shortest O···O distances are comparable to those in Sr2[Cu(OH)6] and are in the range 2.89–3.05, 3.02–3.10 and 3.11–3.15 Å for Sr2[Cu(OH)6], Sr2[Zn(OH)6] and Ba2[Zn(OH)6], respectively. The increasing O···O distances can be attributed to the incorporation of larger cations. Consequently, the strongest hydrogen bonding is expected in Sr2[Cu(OH)6].

Depending on the cation valences, hexahydroxidometallates can be classified in three main groups with general formulae M1[M2(OH)6], M12[M2(OH)6] and M13[M2(OH)6].

In addition to the above-discussed cuprates and zincates, in the M12[M2(OH)6] group there are three complexes with M1I and M2IV cations. Two of them, Li2[Pt(OH)6] (Troemel & Lupprich, 1975a) and Na2[Hf(OH)6] (Troyanov et al., 1999), are rather similar layered compounds with the H atoms directed toward the interlayer space and weak hydrogen bonding between layers. The third one, K2[Pb(OH)6] (Jacobs & Stahl, 2000), shows some similarities with Sr2[Cu(OH)6], because between every two neighboring Pb(OH)6 octahedra there are two hydrogen bonds forming eight-membered pseudo-rings. Together with two K atoms below and above the pseudo-rings, empty octahedral sites around special position 9d in R3 are created. Edge-sharing Pb(OH)6 and □K2(OH)4 (□ is a vacancy) octahedra form pseudo-chains, which are further interconnected by hydrogen bonds only.

A large series of cubic or tetragonal minerals and synthetic compounds make up the M1[M2(OH)6] group of hydroxidometallates (M1= Na, Ca, Cd, Co, Cu, Fe, Mg, Mn and Zn, and M2 = Ge, Pb, Sn and Sb). Structurally, all complexes from this group are very similar (Welch & Crichton, 2002, and references therein; Asai, 1975; Levy-Clement & Billiet, 1976; Morgenstern Badarau, 1976; Morgenstern Badarau & Michel, 1976; Troemel & Lupprich, 1975b). They can be easily compared with Sr2[Cu(OH)6] and isotypic compounds from the M12[M2(OH)6] group if all compounds are considered as derived from the perovskite (ABO3)-type structure consisting of vertex-sharing BO6 octahedra and A cations situated in cuboctahedral positions.

In Sr2[Cu(OH)6] around an empty site at special position 2a, (0, 0, 0), two O2—H2···O3 bonds with neighboring pairs of O1—H1···O3 and O3—H3···O1 bonds form six edges of a very distorted □(OH)6 octahedron (Fig. 3), which shares vertices with Cu(OH)6 octahedra. These two types of octahedra further form an octahedral framework similar to that found in perovskites. The Sr atoms are situated between two vacant special positions, 2c, (1/2, 0, 1/2), and 2d, (1/2, 0, 0), along the zigzag central line of the channel running along the c axis. A very similar framework of alternating M1 and M2 vertex-linked octahedra exists in the M1[M2(OH)6] compounds, but with different hydrogen-bonding topology. While in Sr2[Cu(OH)6] and isotypic compounds hydrogen bonds are concentrated around an empty octahedral site, in the M1[M2(OH)6] structures all octahedral sites are occupied and hydrogen bonds are concentrated around an empty cuboctahedral site. In M1[M2(OH)6], all O atoms act as single donors and acceptors of hydrogen bonds and help to bind the octahedra into a three-dimensional framework. It was concluded that the absence of cuboctahedral cations and hydrogen-bonding topology affect the compressibility of the protonated octahedral framework in M1[M2(OH)6] (Welch & Crichton, 2002; Ross et al., 2002). Therefore, it seems worthwhile to study the compressibility of Sr2[Cu(OH)6] and similar compounds given the absence of some octahedral cations and the different hydrogen bonding topology.

Finally, the M13[M2(OH)6] group comprises three very similar and specific complexes: K3[Sc(OH)6], Rb3[Sc(OH)6] and Rb3[Cr(OH)6] (Hennig & Jacobs, 1992). They contain mutually isolated face-to-face-oriented M2(OH)6 octahedra that are hydrogen bonded in infinite chains. Very weak hydrogen bonds with O···O distances longer than 3 Å form trigonal pyramids between M2(OH)6 octahedra. However, the H atoms are oriented almost directly toward each other and their positions are doubtful.

Related literature top

For related literature, see: Altomare et al. (1999); Brown, 1992; Dowty (2000); Dubler et al. (1973); Đorđević & Karanović (2008); Đorđević et al. (2008); Farrugia (1999); Nadezhina et al. (1980a,b); Sheldrick (2008); Stahl & Jacobs (1998); Stojanović et al. (2008); Westrip (2009); Wills (2009).

Experimental top

Sr2[Cu(OH)6] was synthesized hydrothermally from a mixture of Sr(OH)2.8H2O (Merck, >97%), Cu(OH)2.2H2O (Merck, >99%) and (NH4)2HPO4 (Loba Chemie, >99%). The solid mixture was transferred into a Teflon vessel filled to approximately 70% of its volume with distilled water. The initial pH of the mixture was 8. The Teflon vessel was enclosed in a stainless steel autoclave, which was heated under autogeneous pressure to 373 K, held at this temperature for 72 h and cooled to room temperature over a period of 96 h. The pH of the supernatant solution was 10. The resulting products were filtered, washed thoroughly with distilled water and dried in air at room temperature. The title compound crystallized as prismatic blue transparent crystals (yield ca 5%) together with light-blue powder.

Refinement top

All H atoms were located in difference Fourier maps and their positional parameters refined with the O—H distances restrained to 0.82 (2) Å and fixed displacement parameters Uiso(H) = 1.3Ueq(O).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999); molecular graphics: ATOMS (Dowty, 2000); software used to prepare material for publication: publCIF (Westrip, 2009).

Figures top
[Figure 1] Fig. 1. The coordination environment of the Sr and Cu sites, showing the hydrogen bonding. Displacement ellipsoids are drawn at the 70% probability level. The shorter Sr—O and Cu—O bonds are shown in black, the longer in white and hydrogen bonds as dashed lines. [Symmetry codes: (i) -x + 1, -y, -z + 1; (ii) -x + 3/2, y + 1/2, -z + 1/2; (iii) x - 1/2, -y + 1/2, z - 1/2; (iv) -x + 1/2, y + 1/2, -z + 1/2; (v) -x + 1, -y, -z; (vi) x - 1, y, z; (ix) x + 1, y, z; (xi) -x + 2, -y, -z + 1; (xii) -x + 3/2, y - 1/2, -z + 1/2; (xiii) x + 1/2, -y - 1/2, z + 1/2.]
[Figure 2] Fig. 2. The packing of Cu (dark) and Sr (light) polyhedra (H atoms have been omitted for clarity.)
[Figure 3] Fig. 3. The network of hydrogen bonds around the empty (0, 0, 0) site (black circle) in Sr2[Cu(OH)6]. Full and dashed thin lines emphasize the deformed octahedral geometry of the empty site. H atoms are shown as small circles of arbitrary radii. [Symmetry codes: (iii) x - 1/2, -y + 1/2, z - 1/2; (v) -x + 1, -y, -z; (vi) x - 1, y, z; (viii) -x + 1/2, y - 1/2, -z + 1/2; (x) -x, -y,-z.]
distrontium hexahydroxidocuprate(II) top
Crystal data top
Sr2[Cu(OH)6]F(000) = 318
Mr = 340.84Dx = 3.928 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ynCell parameters from 757 reflections
a = 5.7924 (4) Åθ = 3.3–28.6°
b = 6.1663 (4) ŵ = 22.05 mm1
c = 8.0748 (5) ÅT = 296 K
β = 92.210 (5)°Prism, blue
V = 288.20 (3) Å30.10 × 0.03 × 0.03 mm
Z = 2
Data collection top
Oxford Diffraction Xcalibur
diffractometer with a Sapphire3 (Gemini Mo) detector
586 independent reflections
Radiation source: Enhance (Mo) X-ray Source500 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.021
Detector resolution: 16.3280 pixels mm-1θmax = 26.4°, θmin = 4.2°
ω scansh = 67
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
k = 77
Tmin = 0.459, Tmax = 0.521l = 810
1083 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.024Only H-atom coordinates refined
wR(F2) = 0.047 w = 1/[σ2(Fo2) + (0.0263P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.94(Δ/σ)max < 0.001
586 reflectionsΔρmax = 0.79 e Å3
53 parametersΔρmin = 0.65 e Å3
3 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0165 (14)
Crystal data top
Sr2[Cu(OH)6]V = 288.20 (3) Å3
Mr = 340.84Z = 2
Monoclinic, P21/nMo Kα radiation
a = 5.7924 (4) ŵ = 22.05 mm1
b = 6.1663 (4) ÅT = 296 K
c = 8.0748 (5) Å0.10 × 0.03 × 0.03 mm
β = 92.210 (5)°
Data collection top
Oxford Diffraction Xcalibur
diffractometer with a Sapphire3 (Gemini Mo) detector
586 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
500 reflections with I > 2σ(I)
Tmin = 0.459, Tmax = 0.521Rint = 0.021
1083 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0243 restraints
wR(F2) = 0.047Only H-atom coordinates refined
S = 0.94Δρmax = 0.79 e Å3
586 reflectionsΔρmin = 0.65 e Å3
53 parameters
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
xyzUiso*/Ueq
Sr10.46302 (8)0.07463 (7)0.24985 (5)0.00894 (17)
Cu11.00000.00000.50000.0096 (2)
O10.8917 (6)0.0334 (5)0.2675 (4)0.0111 (7)
H10.951 (8)0.057 (6)0.214 (6)0.014*
O20.3466 (6)0.2241 (5)0.0481 (4)0.0122 (7)
H20.216 (5)0.210 (8)0.007 (6)0.016*
O30.6342 (6)0.2303 (5)0.5642 (4)0.0142 (8)
H30.662 (9)0.319 (7)0.495 (5)0.018*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sr10.0101 (2)0.0068 (2)0.0099 (2)0.0004 (2)0.00073 (16)0.00051 (17)
Cu10.0122 (4)0.0084 (4)0.0082 (4)0.0019 (3)0.0016 (3)0.0001 (3)
O10.0150 (18)0.0093 (18)0.0089 (17)0.0016 (15)0.0016 (13)0.0006 (13)
O20.0086 (17)0.0144 (17)0.0133 (17)0.0030 (16)0.0044 (14)0.0029 (13)
O30.019 (2)0.0095 (17)0.0141 (18)0.0046 (15)0.0004 (15)0.0045 (13)
Geometric parameters (Å, º) top
Sr1—O3i2.484 (3)O1—O3xv3.252 (5)
Sr1—O22.533 (3)O1—O2v3.264 (5)
Sr1—O1ii2.565 (3)O1—O33.299 (5)
Sr1—O12.569 (3)O1—Sr1xi3.384 (3)
Sr1—O3iii2.665 (3)O1—O2xi3.439 (5)
Sr1—O2iv2.765 (3)O1—H10.79 (4)
Sr1—O2v2.839 (3)O2—Cu1viii1.965 (3)
Sr1—O32.856 (3)O2—O1xvi2.736 (5)
Sr1—Cu1iv3.3210 (4)O2—Sr1viii2.765 (3)
Sr1—O1vi3.384 (3)O2—O1xii2.825 (5)
Sr1—Cu13.4499 (5)O2—Sr1v2.839 (3)
Sr1—H12.85 (5)O2—O3viii2.909 (5)
Sr1—H22.96 (4)O2—O3i3.128 (5)
Sr1—H32.71 (5)O2—O3xii3.187 (4)
Cu1—O2iv1.965 (3)O2—O1v3.264 (5)
Cu1—O2vii1.965 (3)O2—O3iii3.288 (5)
Cu1—O1vi1.967 (3)O2—O3xvi3.360 (5)
Cu1—O1i1.967 (3)O2—H20.82 (2)
Cu1—O3vi2.619 (3)O3—Sr1i2.484 (3)
Cu1—O3i2.619 (3)O3—Cu1xi2.619 (3)
Cu1—Sr1viii3.3210 (4)O3—Sr1xvii2.665 (3)
Cu1—Sr1ix3.3210 (4)O3—O1ix2.888 (5)
Cu1—Sr1x3.4499 (5)O3—O2iv2.909 (5)
O1—Cu1xi1.967 (3)O3—O1ii3.048 (5)
O1—Sr1xii2.565 (3)O3—O2i3.128 (5)
O1—O2xiii2.736 (5)O3—O2ii3.187 (4)
O1—O2ii2.825 (5)O3—O1xv3.252 (5)
O1—O3xiv2.888 (5)O3—O2xvii3.288 (5)
O1—O3xii3.048 (5)O3—H30.80 (2)
O3i—Sr1—O277.14 (11)O3xii—O1—O3xv101.59 (12)
O3i—Sr1—O1ii145.97 (11)Cu1xi—O1—O2v143.52 (14)
O2—Sr1—O1ii136.87 (10)Sr1xii—O1—O2v123.06 (12)
O3i—Sr1—O190.64 (11)Sr1—O1—O2v56.76 (9)
O2—Sr1—O194.58 (10)O2xiii—O1—O2v149.52 (13)
O1ii—Sr1—O185.93 (7)O2ii—O1—O2v106.57 (10)
O3i—Sr1—O3iii120.52 (7)O3xiv—O1—O2v56.04 (10)
O2—Sr1—O3iii78.44 (10)O3xii—O1—O2v62.68 (10)
O1ii—Sr1—O3iii76.87 (10)O3xv—O1—O2v146.39 (14)
O1—Sr1—O3iii144.74 (11)Cu1xi—O1—O352.54 (10)
O3i—Sr1—O2iv79.40 (10)Sr1xii—O1—O3131.51 (12)
O2—Sr1—O2iv122.91 (7)Sr1—O1—O356.60 (9)
O1ii—Sr1—O2iv80.27 (10)O2xiii—O1—O366.90 (11)
O1—Sr1—O2iv136.98 (10)O2ii—O1—O362.15 (10)
O3iii—Sr1—O2iv70.33 (10)O3xiv—O1—O3109.71 (9)
O3i—Sr1—O2v149.58 (10)O3xii—O1—O3149.95 (12)
O2—Sr1—O2v78.08 (11)O3xv—O1—O3106.19 (11)
O1ii—Sr1—O2v60.58 (10)O2v—O1—O397.93 (12)
O1—Sr1—O2v74.05 (10)Cu1xi—O1—Sr1xi75.12 (10)
O3iii—Sr1—O2v70.69 (9)Sr1xii—O1—Sr1xi81.94 (9)
O2iv—Sr1—O2v129.52 (6)Sr1—O1—Sr1xi153.00 (12)
O3i—Sr1—O378.24 (11)O2xiii—O1—Sr1xi105.50 (12)
O2—Sr1—O3152.98 (10)O2ii—O1—Sr1xi51.94 (9)
O1ii—Sr1—O368.19 (9)O3xiv—O1—Sr1xi49.51 (8)
O1—Sr1—O374.71 (10)O3xii—O1—Sr1xi94.13 (11)
O3iii—Sr1—O3124.36 (7)O2v—O1—Sr1xi104.83 (11)
O2iv—Sr1—O362.32 (10)O3—O1—Sr1xi113.81 (10)
O2v—Sr1—O3120.77 (10)Cu1xi—O1—O2xi107.75 (14)
O3i—Sr1—Cu1iv170.52 (8)Sr1xii—O1—O2xi52.42 (8)
O2—Sr1—Cu1iv101.85 (8)Sr1—O1—O2xi144.90 (13)
O1ii—Sr1—Cu1iv36.25 (7)O2xiii—O1—O2xi109.84 (12)
O1—Sr1—Cu1iv98.85 (7)O2ii—O1—O2xi95.51 (11)
O3iii—Sr1—Cu1iv50.45 (7)O3xiv—O1—O2xi61.91 (10)
O2iv—Sr1—Cu1iv93.58 (7)O3xii—O1—O2xi52.87 (10)
O2v—Sr1—Cu1iv36.14 (6)O3xv—O1—O2xi55.67 (10)
O3—Sr1—Cu1iv104.25 (6)O2v—O1—O2xi94.20 (11)
O3i—Sr1—O1vi65.21 (10)O3—O1—O2xi156.85 (13)
O2—Sr1—O1vi69.36 (9)Cu1xi—O1—H1109 (4)
O1ii—Sr1—O1vi120.76 (9)Sr1xii—O1—H1119 (4)
O1—Sr1—O1vi153.00 (12)Sr1—O1—H1103 (4)
O3iii—Sr1—O1vi55.51 (9)O2xiii—O1—H1154 (4)
O2iv—Sr1—O1vi53.55 (9)O2ii—O1—H165 (4)
O2v—Sr1—O1vi120.80 (9)O3xii—O1—H182 (4)
O3—Sr1—O1vi109.58 (9)O3xv—O1—H197 (4)
Cu1iv—Sr1—O1vi105.50 (5)O2v—O1—H154 (4)
O3i—Sr1—Cu149.14 (8)O3—O1—H1106 (4)
O2—Sr1—Cu194.93 (8)Sr1xi—O1—H153 (4)
O1ii—Sr1—Cu1114.95 (8)O2xi—O1—H167 (4)
O1—Sr1—Cu1134.76 (7)Cu1viii—O2—Sr1130.22 (16)
O3iii—Sr1—Cu180.48 (8)Cu1viii—O2—O1xvi45.95 (9)
O2iv—Sr1—Cu134.70 (7)Sr1—O2—O1xvi153.97 (16)
O2v—Sr1—Cu1151.12 (7)Cu1viii—O2—Sr1viii92.09 (12)
O3—Sr1—Cu177.02 (7)Sr1—O2—Sr1viii96.30 (11)
Cu1iv—Sr1—Cu1122.063 (13)O1xvi—O2—Sr1viii109.15 (13)
O1vi—Sr1—Cu133.44 (5)Sr1—O2—O1xii91.61 (12)
O3i—Sr1—Cu1xi77.26 (8)O1xvi—O2—O1xii90.06 (13)
O2—Sr1—Cu1xi117.48 (8)Sr1viii—O2—O1xii74.52 (11)
O1ii—Sr1—Cu1xi82.84 (7)Cu1viii—O2—Sr1v85.41 (11)
O1—Sr1—Cu1xi30.76 (7)Sr1—O2—Sr1v101.92 (11)
O3iii—Sr1—Cu1xi159.71 (7)O1xvi—O2—Sr1v54.74 (9)
O2iv—Sr1—Cu1xi106.66 (7)Sr1viii—O2—Sr1v158.09 (14)
O2v—Sr1—Cu1xi99.12 (7)O1xii—O2—Sr1v116.60 (13)
O3—Sr1—Cu1xi45.20 (7)Cu1viii—O2—O3viii106.81 (14)
Cu1iv—Sr1—Cu1xi111.106 (12)Sr1—O2—O3viii119.92 (13)
O1vi—Sr1—Cu1xi139.56 (6)O1xvi—O2—O3viii79.02 (13)
Cu1—Sr1—Cu1xi108.801 (12)Sr1viii—O2—O3viii60.37 (9)
O3i—Sr1—H1106.4 (6)O1xii—O2—O3viii125.94 (15)
O2—Sr1—H198.4 (11)Sr1v—O2—O3viii99.52 (13)
O1ii—Sr1—H172.6 (8)Cu1viii—O2—O3i100.86 (14)
O1—Sr1—H115.7 (6)Sr1—O2—O3i50.74 (8)
O3iii—Sr1—H1130.4 (7)O1xvi—O2—O3i145.21 (15)
O2iv—Sr1—H1138.1 (11)Sr1viii—O2—O3i53.34 (8)
O2v—Sr1—H160.5 (8)O1xii—O2—O3i57.77 (11)
O3—Sr1—H178.0 (11)Sr1v—O2—O3i148.45 (14)
Cu1iv—Sr1—H183.1 (6)O3viii—O2—O3i107.91 (14)
O1vi—Sr1—H1166.1 (9)Cu1viii—O2—O3xii55.15 (10)
Cu1—Sr1—H1148.2 (8)Sr1—O2—O3xii90.95 (11)
Cu1xi—Sr1—H139.7 (9)O1xvi—O2—O3xii66.10 (12)
O3i—Sr1—H280.6 (10)Sr1viii—O2—O3xii140.27 (13)
O2—Sr1—H214.7 (7)O1xii—O2—O3xii66.25 (11)
O1ii—Sr1—H2132.4 (10)Sr1v—O2—O3xii52.10 (8)
O1—Sr1—H2109.0 (7)O3viii—O2—O3xii143.63 (17)
O3iii—Sr1—H265.0 (7)O3i—O2—O3xii106.63 (14)
O2iv—Sr1—H2110.4 (8)Cu1viii—O2—O1v116.58 (14)
O2v—Sr1—H279.9 (10)Sr1—O2—O1v104.04 (11)
O3—Sr1—H2158.5 (10)O1xvi—O2—O1v70.73 (9)
Cu1iv—Sr1—H296.1 (10)Sr1viii—O2—O1v114.51 (12)
O1vi—Sr1—H257.4 (9)O1xii—O2—O1v160.44 (16)
Cu1—Sr1—H286.6 (10)Sr1v—O2—O1v49.19 (8)
Cu1xi—Sr1—H2132.0 (7)O3viii—O2—O1v55.43 (11)
H1—Sr1—H2111.5 (13)O3i—O2—O1v141.74 (13)
O3i—Sr1—H394.6 (4)O3xii—O2—O1v101.29 (13)
O2—Sr1—H3165.8 (10)Cu1viii—O2—O3iii169.16 (17)
O1ii—Sr1—H352.0 (5)Sr1—O2—O3iii52.56 (8)
O1—Sr1—H373.8 (12)O1xvi—O2—O3iii125.91 (14)
O3iii—Sr1—H3115.8 (10)Sr1viii—O2—O3iii98.05 (12)
O2iv—Sr1—H365.6 (11)O1xii—O2—O3iii142.99 (15)
O2v—Sr1—H3105.7 (6)Sr1v—O2—O3iii83.75 (10)
O3—Sr1—H316.3 (9)O3viii—O2—O3iii75.32 (12)
Cu1iv—Sr1—H388.2 (5)O3i—O2—O3iii88.33 (11)
O1vi—Sr1—H3117.9 (11)O3xii—O2—O3iii116.85 (12)
Cu1—Sr1—H388.0 (9)O1v—O2—O3iii55.44 (10)
Cu1xi—Sr1—H348.7 (11)Cu1viii—O2—O3xvi51.12 (9)
H1—Sr1—H372.6 (16)Sr1—O2—O3xvi137.70 (14)
H2—Sr1—H3174.3 (12)O1xvi—O2—O3xvi64.59 (11)
O2iv—Cu1—O2vii180.0Sr1viii—O2—O3xvi46.62 (8)
O2iv—Cu1—O1vi91.83 (13)O1xii—O2—O3xvi62.75 (11)
O2vii—Cu1—O1vi88.17 (13)Sr1v—O2—O3xvi119.28 (12)
O2iv—Cu1—O1i88.17 (13)O3viii—O2—O3xvi64.82 (12)
O2vii—Cu1—O1i91.83 (13)O3i—O2—O3xvi87.07 (12)
O1vi—Cu1—O1i180.000 (1)O3xii—O2—O3xvi106.26 (12)
O2iv—Cu1—O3vi86.85 (12)O1v—O2—O3xvi109.74 (12)
O2vii—Cu1—O3vi93.15 (12)O3iii—O2—O3xvi136.10 (16)
O1vi—Cu1—O3vi90.86 (12)Cu1viii—O2—H2116 (4)
O1i—Cu1—O3vi89.14 (12)Sr1—O2—H2113 (4)
O2iv—Cu1—O3i93.15 (12)O1xvi—O2—H281 (4)
O2vii—Cu1—O3i86.85 (12)Sr1viii—O2—H271 (4)
O1vi—Cu1—O3i89.14 (12)O1xii—O2—H2139 (4)
O1i—Cu1—O3i90.86 (12)Sr1v—O2—H290 (4)
O3vi—Cu1—O3i180.0O3i—O2—H2114 (4)
O2iv—Cu1—Sr1viii121.56 (10)O3xii—O2—H2140 (4)
O2vii—Cu1—Sr1viii58.44 (10)O3iii—O2—H265 (4)
O1vi—Cu1—Sr1viii50.44 (9)O3xvi—O2—H277 (4)
O1i—Cu1—Sr1viii129.56 (9)Sr1i—O3—Cu1xi85.02 (10)
O3vi—Cu1—Sr1viii128.33 (7)Sr1i—O3—Sr1xvii100.10 (12)
O3i—Cu1—Sr1viii51.67 (7)Cu1xi—O3—Sr1xvii77.87 (9)
O2iv—Cu1—Sr1ix58.44 (10)Sr1i—O3—Sr1101.76 (11)
O2vii—Cu1—Sr1ix121.56 (10)Cu1xi—O3—Sr184.11 (10)
O1vi—Cu1—Sr1ix129.56 (9)Sr1xvii—O3—Sr1150.21 (14)
O1i—Cu1—Sr1ix50.44 (9)Sr1i—O3—O1ix91.13 (12)
O3vi—Cu1—Sr1ix51.67 (7)Cu1xi—O3—O1ix151.45 (15)
O3i—Cu1—Sr1ix128.33 (7)Sr1xvii—O3—O1ix74.98 (11)
Sr1viii—Cu1—Sr1ix180.000 (12)Sr1—O3—O1ix124.28 (14)
O2iv—Cu1—Sr153.21 (10)Sr1i—O3—O2iv91.44 (12)
O2vii—Cu1—Sr1126.79 (10)Cu1xi—O3—O2iv139.70 (15)
O1vi—Cu1—Sr171.44 (10)Sr1xvii—O3—O2iv141.88 (14)
O1i—Cu1—Sr1108.56 (10)Sr1—O3—O2iv57.31 (10)
O3vi—Cu1—Sr1134.16 (7)O1ix—O3—O2iv68.53 (12)
O3i—Cu1—Sr145.84 (7)Sr1i—O3—O1ii152.66 (15)
Sr1viii—Cu1—Sr171.327 (9)Cu1xi—O3—O1ii95.61 (12)
Sr1ix—Cu1—Sr1108.673 (9)Sr1xvii—O3—O1ii106.77 (12)
O2iv—Cu1—Sr1x126.79 (10)Sr1—O3—O1ii51.37 (8)
O2vii—Cu1—Sr1x53.21 (10)O1ix—O3—O1ii100.48 (12)
O1vi—Cu1—Sr1x108.56 (10)O2iv—O3—O1ii70.47 (12)
O1i—Cu1—Sr1x71.44 (10)Sr1i—O3—O2i52.13 (9)
O3vi—Cu1—Sr1x45.84 (7)Cu1xi—O3—O2i101.16 (12)
O3i—Cu1—Sr1x134.16 (7)Sr1xvii—O3—O2i56.33 (9)
Sr1viii—Cu1—Sr1x108.673 (9)Sr1—O3—O2i152.02 (13)
Sr1ix—Cu1—Sr1x71.327 (9)O1ix—O3—O2i55.83 (10)
Sr1—Cu1—Sr1x180.0O2iv—O3—O2i108.06 (14)
O2iv—Cu1—Sr1vi99.35 (10)O1ii—O3—O2i152.14 (14)
O2vii—Cu1—Sr1vi80.65 (10)Sr1i—O3—O2ii118.50 (13)
O1vi—Cu1—Sr1vi41.91 (10)Sr1xvii—O3—O2ii57.21 (9)
O1i—Cu1—Sr1vi138.09 (10)Sr1—O3—O2ii94.34 (12)
O3vi—Cu1—Sr1vi50.68 (8)O1ix—O3—O2ii126.14 (14)
O3i—Cu1—Sr1vi129.32 (8)O2iv—O3—O2ii143.63 (17)
Sr1viii—Cu1—Sr1vi80.669 (9)O1ii—O3—O2ii73.89 (12)
Sr1ix—Cu1—Sr1vi99.331 (9)O2i—O3—O2ii106.76 (14)
Sr1—Cu1—Sr1vi108.801 (12)Sr1i—O3—O1xv70.87 (10)
Sr1x—Cu1—Sr1vi71.199 (12)Sr1xvii—O3—O1xv50.18 (8)
O2iv—Cu1—Sr1i80.65 (10)Sr1—O3—O1xv120.30 (12)
O2vii—Cu1—Sr1i99.35 (10)O1ix—O3—O1xv115.19 (12)
O1vi—Cu1—Sr1i138.09 (10)O2iv—O3—O1xv161.68 (14)
O1i—Cu1—Sr1i41.91 (10)O1ii—O3—O1xv123.90 (16)
O3vi—Cu1—Sr1i129.32 (8)O2i—O3—O1xv65.19 (10)
O3i—Cu1—Sr1i50.68 (8)O2ii—O3—O1xv50.27 (10)
Sr1viii—Cu1—Sr1i99.331 (9)Sr1i—O3—O2xvii144.94 (14)
Sr1ix—Cu1—Sr1i80.669 (9)Cu1xi—O3—O2xvii100.80 (12)
Sr1—Cu1—Sr1i71.199 (12)Sr1xvii—O3—O2xvii49.00 (8)
Sr1x—Cu1—Sr1i108.801 (12)Sr1—O3—O2xvii113.19 (12)
Sr1vi—Cu1—Sr1i180.000 (13)O1ix—O3—O2xvii67.31 (11)
Cu1xi—O1—Sr1xii93.31 (12)O2iv—O3—O2xvii104.68 (12)
Cu1xi—O1—Sr1107.33 (14)O1ii—O3—O2xvii61.87 (10)
Sr1xii—O1—Sr1124.04 (12)O2i—O3—O2xvii92.98 (12)
Cu1xi—O1—O2xiii45.89 (10)O2ii—O3—O2xvii63.15 (12)
Sr1xii—O1—O2xiii64.68 (10)O1xv—O3—O2xvii92.91 (12)
Sr1—O1—O2xiii93.73 (13)Sr1i—O3—O1100.66 (11)
Sr1xii—O1—O2ii119.65 (14)Sr1xvii—O3—O1107.32 (12)
Sr1—O1—O2ii110.60 (13)Sr1—O3—O148.69 (8)
O2xiii—O1—O2ii89.94 (13)O1ix—O3—O1167.24 (14)
Cu1xi—O1—O3xiv109.30 (14)O2iv—O3—O1105.98 (14)
Sr1xii—O1—O3xiv114.26 (13)O1ii—O3—O166.77 (9)
Sr1—O1—O3xiv106.90 (13)O2i—O3—O1136.13 (13)
O2xiii—O1—O3xiv152.70 (16)O2ii—O3—O151.60 (10)
O2ii—O1—O3xiv66.40 (12)O1xv—O3—O173.81 (11)
Cu1xi—O1—O3xii153.12 (16)O2xvii—O3—O1104.32 (12)
Sr1xii—O1—O3xii60.44 (9)Sr1i—O3—H3173 (4)
Sr1—O1—O3xii93.47 (12)Cu1xi—O3—H393 (4)
O2xiii—O1—O3xii117.63 (13)Sr1xvii—O3—H386 (4)
O2ii—O1—O3xii142.47 (15)Sr1—O3—H371 (4)
O3xiv—O1—O3xii79.52 (12)O1ix—O3—H394 (4)
Cu1xi—O1—O3xv53.65 (10)O2iv—O3—H386 (4)
Sr1xii—O1—O3xv52.94 (8)O2i—O3—H3135 (4)
Sr1—O1—O3xv156.75 (14)O2ii—O3—H362 (4)
O2xiii—O1—O3xv63.63 (11)O1xv—O3—H3111 (4)
O2ii—O1—O3xv66.70 (11)O1—O3—H374 (4)
O3xiv—O1—O3xv93.31 (11)
Symmetry codes: (i) x+1, y, z+1; (ii) x+3/2, y+1/2, z+1/2; (iii) x1/2, y+1/2, z1/2; (iv) x+1/2, y+1/2, z+1/2; (v) x+1, y, z; (vi) x1, y, z; (vii) x1/2, y1/2, z+1/2; (viii) x+1/2, y1/2, z+1/2; (ix) x1/2, y+1/2, z+1/2; (x) x, y, z+1; (xi) x+1, y, z; (xii) x+3/2, y1/2, z+1/2; (xiii) x+1/2, y1/2, z+1/2; (xiv) x+1/2, y+1/2, z1/2; (xv) x+2, y, z+1; (xvi) x1/2, y1/2, z1/2; (xvii) x+1/2, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3xiv0.79 (4)2.10 (4)2.888 (5)174 (4)
O2—H2···O3viii0.82 (3)2.12 (3)2.909 (5)162 (3)
O3—H3···O1ii0.80 (4)2.32 (4)3.048 (5)152 (4)
Symmetry codes: (ii) x+3/2, y+1/2, z+1/2; (viii) x+1/2, y1/2, z+1/2; (xiv) x+1/2, y+1/2, z1/2.

Experimental details

Crystal data
Chemical formulaSr2[Cu(OH)6]
Mr340.84
Crystal system, space groupMonoclinic, P21/n
Temperature (K)296
a, b, c (Å)5.7924 (4), 6.1663 (4), 8.0748 (5)
β (°) 92.210 (5)
V3)288.20 (3)
Z2
Radiation typeMo Kα
µ (mm1)22.05
Crystal size (mm)0.10 × 0.03 × 0.03
Data collection
DiffractometerOxford Diffraction Xcalibur
diffractometer with a Sapphire3 (Gemini Mo) detector
Absorption correctionMulti-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
Tmin, Tmax0.459, 0.521
No. of measured, independent and
observed [I > 2σ(I)] reflections
1083, 586, 500
Rint0.021
(sin θ/λ)max1)0.625
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.047, 0.94
No. of reflections586
No. of parameters53
No. of restraints3
H-atom treatmentOnly H-atom coordinates refined
Δρmax, Δρmin (e Å3)0.79, 0.65

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999), ATOMS (Dowty, 2000), publCIF (Westrip, 2009).

Selected geometric parameters (Å, º) top
Sr1—O3i2.484 (3)Sr1—O2v2.839 (3)
Sr1—O22.533 (3)Sr1—O32.856 (3)
Sr1—O1ii2.565 (3)Sr1—O1vi3.384 (3)
Sr1—O12.569 (3)Cu1—O2iv1.965 (3)
Sr1—O3iii2.665 (3)Cu1—O1vi1.967 (3)
Sr1—O2iv2.765 (3)Cu1—O3vi2.619 (3)
O2iv—Cu1—O1vi91.83 (13)O1vi—Cu1—O3vi90.86 (12)
O2iv—Cu1—O1i88.17 (13)O1i—Cu1—O3vi89.14 (12)
O2iv—Cu1—O3vi86.85 (12)O2iv—Cu1—O3i93.15 (12)
Symmetry codes: (i) x+1, y, z+1; (ii) x+3/2, y+1/2, z+1/2; (iii) x1/2, y+1/2, z1/2; (iv) x+1/2, y+1/2, z+1/2; (v) x+1, y, z; (vi) x1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3vii0.79 (4)2.10 (4)2.888 (5)174 (4)
O2—H2···O3viii0.82 (3)2.12 (3)2.909 (5)162 (3)
O3—H3···O1ii0.80 (4)2.32 (4)3.048 (5)152 (4)
Symmetry codes: (ii) x+3/2, y+1/2, z+1/2; (vii) x+1/2, y+1/2, z1/2; (viii) x+1/2, y1/2, z+1/2.
 

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