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Acta Cryst. (2012). E68, i3-i4    [ doi:10.1107/S1600536811052020 ]

Silver diaquacobalt(II) catena-borodiphosphate(V) hydrate, (Ag0.79Co0.11)Co(H2O)2[BP2O8]·0.67H2O

H. Zouihri, M. Saadi, B. Jaber and L. El Ammari

Abstract top

The structure of the title compound, (Ag0.79Co0.11)Co(H2O)2[BP2O8]·0.67H2O is isotypic to that of its recently published counterparts AgMg(H2O)2[BP2O8]·H2O and (Ag0.57Ni0.22)Ni(H2O)2[BP2O8]·0.67H2O. It consists of infinite borophos­phate helical ribbons [BP2O8]3-, built up from alternate BO4 and PO4 tetra­hedra arranged around the 65 screw axes. The vertex-sharing BO4 and PO4 tetra­hedra form a spiral ribbon of four-membred rings in which BO4 and PO4 groups alternate. The ribbons are connected through slightly distorted CoO4(H2O)2 octa­hedra whose four O atoms belong to the phosphate groups. The resulting three-dimensional framework is characterized by hexa­gonal channels running along [001] in which the remaining water mol­ecules are located. The main difference between the Mg-containing and the title structure lies in the filling ratio of Wyckoff positions 6a and 6b in the tunnels. The refinement of the occupancy rate of the site 6a shows that it is occupied by water at 67%, while the refinement of that of the site 6b shows that this site is partially occupied by 78.4% Ag and 10.8% Co, for a total of 82.2%. The structure is stabilized by O-H...O hydrogen bonds between water mol­ecules and O atoms that are part of the helices.

Comment top

A large group of borophosphates is known with a molar ratio of B:P = 1:2 and helical structure type, which consist of loop branched chain anions built from tetrahedral BO4 and PO4 units (Kniep et al., (1998); Menezes et al.,(2008) and Lin et al. (2008)).

The aim of this work is the synthesis and the crystal structure of a new borophosphate-hydrate (Ag0.79Co0.11)Co(H2O)2[BP2O8],0.67(H2O), which is isotypic to the analogue nickel and magnesium borophosphates (Ag0.57Ni0.22)Ni(H2O)2[BP2O8],0.67(H2O); AgMg(H2O)2[BP2O8],H2O recently published (Zouihri et al., 2011a, 2011b)) and to M(I)M(II)(H2O)2[BP2O8] H2O (M(I)=Li, Na, K, NH4+; M(II)= Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd) (Kniep et al., (1997) and Ewald et al., (2007)).

The anionic partial structure of the title compound contains one–dimensional infinite helices, [BP2O8]3-, which are wound around 65 axis. It is built up from alternate borate (BO4) and phosphate (PO4) tetrahedra, forming a spiral ribbon. The Co2+ cations have a slightly distorted octahedral oxygen coordination by four oxygen atoms from the phosphate anion and by two from water molecules as shown in Fig.1. The ribbons are interconnected through CoO4(H2O)2 octahedra. The resulting 3-D framework shows hexagonal tunnels running along c direction where water molecules are located (Fig.2).

The main difference between the structure of this compound and that of his counterpart AgMg(H2O)2[BP2O8],H2O lies in the filling ratio of the Wyckoff positions 6a and 6 b in tunnels. Indeed, in this work, the refinement of the occupancy rate of the sites 6a and 6 b (space group P6522) shows that the first is occupied by water at 67% and the second is partially occupied by 78.4% of Ag and 10.8% of Co for a total of 82.2%. Note that in this case, the sum of the occupancie rate is restrained to fit the charge balance. While in the case of AgMg(H2O)2[BP2O8],H2O structure these two sites are completely occupied by H2O and Ag+ respectively.

It is interesting to compare the lattice parameters and volumes of title compound (Table 1) with some borophosphates of this family like AgMg(H2O)2[BP2O8],H2O (a = 9.4577 (4) Å, c = 15.830 (2)Å and V = 1226.4 (2)Å3) and (Ag0.57Ni0.22)Ni(H2O)2[BP2O8],0.67(H2O) (a = 9.3848 (6) Å, c = 15.841 (2)Å and V = 1208.3 (2)Å3). The ionic radii of MgII, CoII, and NiII in the octahedral site are 0.72 Å, 0.74 Å and 0.69 Å, respectively (Shannon, 1976). The difference between these values is very small, therefore the filling rate of 6a and 6 b sites by (AgI/ MII) and H2O, respectively, leads to the variation of the lattice parameters and volumes of these compounds. Indeed the obtained values for the title compound are between these of the two precedents borophosphates as expected.

The structure is stabilized by O—H···O hydrogen bonds between water molecules and O atoms that are part of the helices (Table 2).

Related literature top

For the isotypic Mg analogue, see: Zouihri et al. (2011a,b); Menezes et al. (2008). For other similar borophosphates, see: Kniep et al. (1997, 1998); Ewald et al. (2007); Lin et al. (2008). For ionic radii, see: Shannon (1976).

Experimental top

The title borophosphate compound was hydrothermally synthesized at 453 °K for 7 days in a 25 ml Teflon-lined steel autoclave from the mixture of CoCO3, H3BO3, H3PO4 (85%), AgNO3 and 5 ml of distilled water in the molar ratio of 1:4:6:1:165. The reaction product was separated by filtration, washed with hot water and dried in air. The pink hexagonal bipyramid crystals obtained were up to 0.15 mm in length. Except for boron and hydrogen the presence of the elements were additionally confirmed by EDAX measurements. Indeed, the results of semi quantitative EDAX measurements are: Element, in At %: BK = 22.45; OK = 59.13; PK = 8.88; Ag L = 4.68, Co = 4.87 K. These values show a large excess of boron which is not surprising because the excess of boron comes from the synthesis of crystals.

Refinement top

The highest peak and the minimum peak in the difference map are at 0.89 Å and 0.98 Å respectively from Ag1 and P atoms. The O-bound H atom is initially located in a difference map and refined with O—H distance restraints of 0.86 (1). In a the last cycle there is refined in the riding model approximation with Uiso(H) set to 1.5Ueq(O). The 340 Friedel opposite reflections are not merged.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. Partial plot of (Ag0.79Co0.11)Co(H2O)2[BP2O8],0.67(H2O) crystal structure showing polyhedra linkage. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) -y + 1, -x + 1, -z + 13/6; (ii) y - 1, -x + y, z + 1/6; (iii) y - 1, x, -z + 5/3; (iv) x, x-y + 1, -z + 11/6; (v) -x + y - 1, y, -z + 3/2; (vi) -x, -x + y, -z + 4/3; (vii) y, x + 1, -z + 5/3; (viii) x-y + 1, -y + 2, -z + 2.
[Figure 2] Fig. 2. Projection view of the (Ag0.79Co0.11)Co(H2O)2[BP2O8],0.67(H2O) framework structure showing tunnel running along c direction where water molecules are located.
Silver diaquacobalt(II) catena-borodiphosphate(V) hydrate top
Crystal data top
(Ag0.79Co0.11)Co(H2O)2[BP2O8]·0.67H2ODx = 3.274 Mg m3
Mr = 398.78Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6522Cell parameters from 974 reflections
Hall symbol: P 65 2 ( 0 0 1)θ = 2.8–27.9°
a = 9.4321 (11) ŵ = 4.63 mm1
c = 15.750 (4) ÅT = 296 K
V = 1213.5 (4) Å3Prism, pink
Z = 60.16 × 0.12 × 0.10 mm
F(000) = 1155
Data collection top
Bruker APEXII CCD detector
974 independent reflections
Radiation source: fine-focus sealed tube748 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.096
ω and ϕ scansθmax = 27.9°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1999)
h = 1211
Tmin = 0.519, Tmax = 0.630k = 1012
7995 measured reflectionsl = 1520
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.093 w = 1/[σ2(Fo2) + (0.0409P)2 + 1.3662P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
974 reflectionsΔρmax = 0.83 e Å3
77 parametersΔρmin = 0.54 e Å3
1 restraintAbsolute structure: Flack (1983), 340 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.05 (5)
Crystal data top
(Ag0.79Co0.11)Co(H2O)2[BP2O8]·0.67H2OZ = 6
Mr = 398.78Mo Kα radiation
Hexagonal, P6522µ = 4.63 mm1
a = 9.4321 (11) ÅT = 296 K
c = 15.750 (4) Å0.16 × 0.12 × 0.10 mm
V = 1213.5 (4) Å3
Data collection top
Bruker APEXII CCD detector
974 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1999)
748 reflections with I > 2σ(I)
Tmin = 0.519, Tmax = 0.630Rint = 0.096
7995 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.093Δρmax = 0.83 e Å3
S = 1.07Δρmin = 0.54 e Å3
974 reflectionsAbsolute structure: Flack (1983), 340 Friedel pairs
77 parametersAbsolute structure parameter: 0.05 (5)
1 restraint
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*/UeqOcc. (<1)
Ag10.18406 (7)0.81594 (7)1.08330.0491 (4)0.784 (3)
Co10.18406 (7)0.81594 (7)1.08330.0491 (4)0.1082 (16)
Co20.10332 (14)0.55166 (7)0.91670.0195 (3)
P0.16844 (18)0.77958 (17)0.75218 (11)0.0176 (3)
B0.1524 (6)0.6952 (12)0.75000.019 (2)
O10.1357 (6)0.6203 (5)0.7906 (2)0.0224 (11)
O20.3146 (5)0.9298 (5)0.7861 (2)0.0214 (10)
O30.0203 (5)0.8048 (5)0.7667 (3)0.0195 (10)
O40.1833 (5)0.7642 (5)0.6541 (2)0.0184 (9)
O50.2914 (5)0.8033 (5)0.9461 (3)0.0263 (11)
O60.1183 (13)1.00001.00000.099 (6)0.67
Atomic displacement parameters (Å2) top
Ag10.0534 (6)0.0534 (6)0.0438 (7)0.0292 (6)0.0038 (5)0.0038 (5)
Co10.0534 (6)0.0534 (6)0.0438 (7)0.0292 (6)0.0038 (5)0.0038 (5)
Co20.0187 (6)0.0184 (5)0.0214 (5)0.0093 (3)0.0000.0008 (5)
P0.0170 (8)0.0188 (8)0.0170 (7)0.0090 (6)0.0001 (7)0.0000 (7)
B0.021 (4)0.022 (5)0.014 (4)0.011 (3)0.004 (4)0.000
O10.028 (3)0.022 (2)0.018 (2)0.012 (2)0.0026 (18)0.0037 (17)
O20.017 (2)0.020 (2)0.022 (2)0.006 (2)0.0012 (17)0.0000 (18)
O30.014 (2)0.016 (2)0.027 (2)0.0063 (18)0.0020 (17)0.0056 (18)
O40.019 (2)0.018 (2)0.019 (2)0.0094 (19)0.0011 (16)0.0008 (16)
O50.022 (2)0.026 (3)0.027 (2)0.009 (2)0.0065 (18)0.0060 (19)
O60.032 (6)0.075 (11)0.204 (17)0.038 (6)0.043 (6)0.085 (12)
Geometric parameters (Å, º) top
Ag1—O5i2.414 (4)P—O31.547 (4)
Ag1—O52.414 (4)P—O41.564 (4)
Ag1—O6i2.489 (8)B—O3v1.452 (7)
Ag1—O62.490 (8)B—O31.452 (7)
Co2—O12.063 (4)B—O4iii1.475 (7)
Co2—O1ii2.063 (4)B—O4vi1.475 (7)
Co2—O2iii2.084 (4)O2—Co2vii2.084 (4)
Co2—O2iv2.084 (4)O4—Bvi1.475 (7)
Co2—O52.188 (4)O5—H5A0.8601
Co2—O5ii2.188 (4)O5—H5B0.8600
P—O21.497 (4)O6—Ag1viii2.490 (8)
P—O11.502 (4)O6—H6A0.8785
O5i—Ag1—O5132.1 (2)O1—P—O3110.2 (3)
O5i—Ag1—O6i79.6 (2)O2—P—O4111.0 (2)
O5—Ag1—O6i147.77 (18)O1—P—O4106.7 (2)
O5i—Ag1—O6147.77 (18)O3—P—O4106.8 (2)
O5—Ag1—O679.6 (2)O3v—B—O3103.8 (7)
O6i—Ag1—O669.9 (4)O3v—B—O4iii113.5 (2)
O1—Co2—O1ii165.3 (3)O3—B—O4iii112.5 (2)
O1—Co2—O2iii100.77 (16)O3v—B—O4vi112.5 (2)
O1ii—Co2—O2iii89.30 (16)O3—B—O4vi113.5 (2)
O1—Co2—O2iv89.30 (16)O4iii—B—O4vi101.5 (7)
O1ii—Co2—O2iv100.77 (17)P—O1—Co2128.7 (3)
O2iii—Co2—O2iv94.3 (3)P—O2—Co2vii139.9 (3)
O1—Co2—O587.21 (16)B—O3—P129.9 (4)
O1ii—Co2—O582.44 (16)Bvi—O4—P130.2 (4)
O2iii—Co2—O587.56 (18)Co2—O5—Ag196.38 (15)
O2iv—Co2—O5176.30 (15)Co2—O5—H5A109.6
O1—Co2—O5ii82.44 (16)Ag1—O5—H5A101.7
O1ii—Co2—O5ii87.21 (16)Co2—O5—H5B101.0
O2iii—Co2—O5ii176.31 (15)Ag1—O5—H5B141.3
O2iv—Co2—O5ii87.56 (18)H5A—O5—H5B104.5
O5—Co2—O5ii90.8 (3)Ag1—O6—Ag1viii106.6 (5)
O2—P—O1115.7 (3)Ag1—O6—H6A99.5
O2—P—O3106.1 (3)Ag1viii—O6—H6A20.2
Symmetry codes: (i) y+1, x+1, z+13/6; (ii) x, xy+1, z+11/6; (iii) y1, x+y, z+1/6; (iv) y1, x, z+5/3; (v) x+y1, y, z+3/2; (vi) x, x+y, z+4/3; (vii) y, x+1, z+5/3; (viii) xy+1, y+2, z+2.
Hydrogen-bond geometry (Å, º) top
O5—H5A···O4ix0.861.892.748 (6)178
O5—H5B···O20.861.902.750 (6)171
O6—H6A···O5viii0.882.443.139 (11)137
Symmetry codes: (viii) xy+1, y+2, z+2; (ix) x+y, x+1, z+1/3.

Experimental details

Crystal data
Chemical formula(Ag0.79Co0.11)Co(H2O)2[BP2O8]·0.67H2O
Crystal system, space groupHexagonal, P6522
Temperature (K)296
a, c (Å)9.4321 (11), 15.750 (4)
V3)1213.5 (4)
Radiation typeMo Kα
µ (mm1)4.63
Crystal size (mm)0.16 × 0.12 × 0.10
Data collection
DiffractometerBruker APEXII CCD detector
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1999)
Tmin, Tmax0.519, 0.630
No. of measured, independent and
observed [I > 2σ(I)] reflections
7995, 974, 748
(sin θ/λ)max1)0.658
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.093, 1.07
No. of reflections974
No. of parameters77
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.83, 0.54
Absolute structureFlack (1983), 340 Friedel pairs
Absolute structure parameter0.05 (5)

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 2006), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
O5—H5A···O4i0.861.892.748 (6)178.1
O5—H5B···O20.861.902.750 (6)170.6
O6—H6A···O5ii0.882.443.139 (11)136.9
Symmetry codes: (i) x+y, x+1, z+1/3; (ii) xy+1, y+2, z+2.
Acknowledgements top

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.