Silver diaquacobalt(II) catena-borodiphosphate(V) hydrate, (Ag_0.79Co_0.11)Co(H₂O)₂[BP₂O₈]·0.67H₂O

The structure of the title compound, (Ag_0.79Co_0.11)Co(H₂O)₂[BP₂O₈]·0.67H₂O is isotypic to that of its recently published counterparts AgMg(H₂O)₂[BP₂O₈]·H₂O and (Ag_0.57Ni_0.22)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.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](O-B) = 0.009 Å
• Disorder in main residue
• R factor = 0.040
• wR factor = 0.093
• Data-to-parameter ratio = 12.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT041_ALERT_1_C Calc. and Reported SumFormula    Strings  Differ          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.17 Ratio
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing)...          ?
PLAT077_ALERT_4_C Unitcell contains non-integer number of atoms ..          ?
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          1

Alert level G
CELLZ01_ALERT_1_G Difference between formula and atom_site contents detected.
CELLZ01_ALERT_1_G ALERT: check formula stoichiometry or atom site occupancies.
           From the CIF: _cell_formula_units_Z    6
           From the CIF: _chemical_formula_sum  Ag0.79 B Co1.11 H5.33 O10.67 P2
           TEST: Compare cell contents of formula and atom_site data

           atom    Z*formula  cif sites diff
           Ag         4.74      4.70    0.04
           B          6.00      6.00    0.00
           Co         6.66      6.65    0.01
           H         31.98     32.04   -0.06
           O         64.02     64.02    0.00
           P         12.00     12.00    0.00
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.90
           From the CIF: _reflns_number_total                974
           Count of symmetry unique reflns          634
           Completeness (_total/calc)            153.63%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       340
           Fraction of Friedel pairs measured     0.536
           Are heavy atom types Z>Si present        yes
PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension .          1
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT301_ALERT_3_G Note: Main Residue  Disorder ...................          8 Perc.
PLAT302_ALERT_4_G Note: Anion/Solvent Disorder ...................        100 Perc.
PLAT779_ALERT_4_G Suspect or Irrelevant (Bond) Angle in CIF .... #         46
              AG1  -O6   -H6A     5.677   1.555   1.555             20.20 Deg.
PLAT791_ALERT_4_G Note: The Model has Chirality at P      (Verify)          S
PLAT811_ALERT_5_G No ADDSYM Analysis: Too Many Excluded Atoms ....          !
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   5 ALERT level C = Check. Ensure it is not caused by an omission or oversight
  11 ALERT level G = General information/check it is not something unexpected

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

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S1. Comment

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 (Ag_0.79Co_0.11)Co(H₂O)₂[BP₂O₈],0.67(H₂O), which is isotypic to the analogue nickel and magnesium borophosphates (Ag_0.57Ni_0.22)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 (Ag_0.57Ni_0.22)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 Mg_II, Co_II, and Ni_II 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 (Ag_I/ M_II) 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

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).

S2. Experimental

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.

S3. Refinement

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 U_iso(H) set to 1.5U_eq(O). The 340 Friedel opposite reflections are not merged.

Computing details

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

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.

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

Crystal data

(Ag0.79Co0.11)Co(H2O)2[BP2O8]·0.67H2O	Dx = 3.274 Mg m^−3
Mr = 398.78	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6522	Cell parameters from 974 reflections
Hall symbol: P 65 2 ( 0 0 1)	θ = 2.8–27.9°
a = 9.4321 (11) Å	µ = 4.63 mm^−1
c = 15.750 (4) Å	T = 296 K
V = 1213.5 (4) Å^3	Prism, pink
Z = 6	0.16 × 0.12 × 0.10 mm
F(000) = 1155

Data collection

Bruker APEXII CCD detector diffractometer	974 independent reflections
Radiation source: fine-focus sealed tube	748 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.096
ω and ϕ scans	θmax = 27.9°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1999)	h = −12→11
Tmin = 0.519, Tmax = 0.630	k = −10→12
7995 measured reflections	l = −15→20

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	H-atom parameters constrained
wR(F^2) = 0.093	w = 1/[σ^2(Fo^2) + (0.0409P)^2 + 1.3662P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
974 reflections	Δρmax = 0.83 e Å^−3
77 parameters	Δρmin = −0.54 e Å^−3
1 restraint	Absolute structure: Flack (1983), 340 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.05 (5)

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	Occ. (<1)
Ag1	0.18406 (7)	0.81594 (7)	1.0833	0.0491 (4)	0.784 (3)
Co1	0.18406 (7)	0.81594 (7)	1.0833	0.0491 (4)	0.1082 (16)
Co2	0.10332 (14)	0.55166 (7)	0.9167	0.0195 (3)
P	0.16844 (18)	0.77958 (17)	0.75218 (11)	0.0176 (3)
B	−0.1524 (6)	0.6952 (12)	0.7500	0.019 (2)
O1	0.1357 (6)	0.6203 (5)	0.7906 (2)	0.0224 (11)
O2	0.3146 (5)	0.9298 (5)	0.7861 (2)	0.0214 (10)
O3	0.0203 (5)	0.8048 (5)	0.7667 (3)	0.0195 (10)
O4	0.1833 (5)	0.7642 (5)	0.6541 (2)	0.0184 (9)
O5	0.2914 (5)	0.8033 (5)	0.9461 (3)	0.0263 (11)
H5A	0.3808	0.8058	0.9599	0.039*
H5B	0.3104	0.8472	0.8965	0.039*
O6	0.1183 (13)	1.0000	1.0000	0.099 (6)	0.67
H6A	0.2180	1.0790	0.9885	0.148*	0.67

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.0534 (6)	0.0534 (6)	0.0438 (7)	0.0292 (6)	−0.0038 (5)	−0.0038 (5)
Co1	0.0534 (6)	0.0534 (6)	0.0438 (7)	0.0292 (6)	−0.0038 (5)	−0.0038 (5)
Co2	0.0187 (6)	0.0184 (5)	0.0214 (5)	0.0093 (3)	0.000	0.0008 (5)
P	0.0170 (8)	0.0188 (8)	0.0170 (7)	0.0090 (6)	0.0001 (7)	0.0000 (7)
B	0.021 (4)	0.022 (5)	0.014 (4)	0.011 (3)	0.004 (4)	0.000
O1	0.028 (3)	0.022 (2)	0.018 (2)	0.012 (2)	0.0026 (18)	0.0037 (17)
O2	0.017 (2)	0.020 (2)	0.022 (2)	0.006 (2)	−0.0012 (17)	0.0000 (18)
O3	0.014 (2)	0.016 (2)	0.027 (2)	0.0063 (18)	−0.0020 (17)	−0.0056 (18)
O4	0.019 (2)	0.018 (2)	0.019 (2)	0.0094 (19)	−0.0011 (16)	0.0008 (16)
O5	0.022 (2)	0.026 (3)	0.027 (2)	0.009 (2)	−0.0065 (18)	0.0060 (19)
O6	0.032 (6)	0.075 (11)	0.204 (17)	0.038 (6)	−0.043 (6)	−0.085 (12)

Geometric parameters (Å, º)

Ag1—O5^i	2.414 (4)	P—O3	1.547 (4)
Ag1—O5	2.414 (4)	P—O4	1.564 (4)
Ag1—O6^i	2.489 (8)	B—O3^v	1.452 (7)
Ag1—O6	2.490 (8)	B—O3	1.452 (7)
Co2—O1	2.063 (4)	B—O4^iii	1.475 (7)
Co2—O1^ii	2.063 (4)	B—O4^vi	1.475 (7)
Co2—O2^iii	2.084 (4)	O2—Co2^vii	2.084 (4)
Co2—O2^iv	2.084 (4)	O4—B^vi	1.475 (7)
Co2—O5	2.188 (4)	O5—H5A	0.8601
Co2—O5^ii	2.188 (4)	O5—H5B	0.8600
P—O2	1.497 (4)	O6—Ag1^viii	2.490 (8)
P—O1	1.502 (4)	O6—H6A	0.8785
O5^i—Ag1—O5	132.1 (2)	O1—P—O3	110.2 (3)
O5^i—Ag1—O6^i	79.6 (2)	O2—P—O4	111.0 (2)
O5—Ag1—O6^i	147.77 (18)	O1—P—O4	106.7 (2)
O5^i—Ag1—O6	147.77 (18)	O3—P—O4	106.8 (2)
O5—Ag1—O6	79.6 (2)	O3^v—B—O3	103.8 (7)
O6^i—Ag1—O6	69.9 (4)	O3^v—B—O4^iii	113.5 (2)
O1—Co2—O1^ii	165.3 (3)	O3—B—O4^iii	112.5 (2)
O1—Co2—O2^iii	100.77 (16)	O3^v—B—O4^vi	112.5 (2)
O1^ii—Co2—O2^iii	89.30 (16)	O3—B—O4^vi	113.5 (2)
O1—Co2—O2^iv	89.30 (16)	O4^iii—B—O4^vi	101.5 (7)
O1^ii—Co2—O2^iv	100.77 (17)	P—O1—Co2	128.7 (3)
O2^iii—Co2—O2^iv	94.3 (3)	P—O2—Co2^vii	139.9 (3)
O1—Co2—O5	87.21 (16)	B—O3—P	129.9 (4)
O1^ii—Co2—O5	82.44 (16)	B^vi—O4—P	130.2 (4)
O2^iii—Co2—O5	87.56 (18)	Co2—O5—Ag1	96.38 (15)
O2^iv—Co2—O5	176.30 (15)	Co2—O5—H5A	109.6
O1—Co2—O5^ii	82.44 (16)	Ag1—O5—H5A	101.7
O1^ii—Co2—O5^ii	87.21 (16)	Co2—O5—H5B	101.0
O2^iii—Co2—O5^ii	176.31 (15)	Ag1—O5—H5B	141.3
O2^iv—Co2—O5^ii	87.56 (18)	H5A—O5—H5B	104.5
O5—Co2—O5^ii	90.8 (3)	Ag1—O6—Ag1^viii	106.6 (5)
O2—P—O1	115.7 (3)	Ag1—O6—H6A	99.5
O2—P—O3	106.1 (3)	Ag1^viii—O6—H6A	20.2

Symmetry codes: (i) −y+1, −x+1, −z+13/6; (ii) x, x−y+1, −z+11/6; (iii) y−1, −x+y, z+1/6; (iv) y−1, x, −z+5/3; (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.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5A···O4^ix	0.86	1.89	2.748 (6)	178
O5—H5B···O2	0.86	1.90	2.750 (6)	171
O6—H6A···O5^viii	0.88	2.44	3.139 (11)	137

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