Silver(I) di­aqua­magnesium catena-borodiphosphate(V) monohydrate, AgMg(H₂O)₂[BP₂O₈]·H₂O

The title compound contains infinite one-dimensional [BP₂O₈]³⁻ borophosphate helical ribbons, 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-membered rings in which BO₄ and PO₄ groups alternate. The ribbons are connected through slightly distorted MgO₄(H₂O)₂ octa­hedra, in which the four O atoms belong to the phosphate groups. The free threads of the helices are occupied by silver ions, which are in an irregular environment surrounded by six O atoms. The central channels of the helices, running along the c axis, are filled with the water mol­ecules. The structure is stabilized by O—H⋯O hydrogen bonds between the water mol­ecules and O atoms that are part of the helices. The crystal structure of the title compound is isotopic with other analogous borophosphates such as A^IM^II(H₂O)₂[BP₂O₈]·H₂O, where A^I = Li, Na, K or NH₄⁺ and M^II = Mg, Mn, Fe, Co, Ni, Cu, Zn or Cd.

Related literature

For isotypic Mg analogues, see: Kniep et al. (1997); Lin et al. (2008). For other similar borophosphates, see: Kniep et al. (1998); Ewald et al. (2007); Menezes et al. (2008).

Experimental

Crystal data

• AgMg(H₂O)₂[BP₂O₈]·H₂O

• M_r = 386.98

• Hexagonal, P 6₅ 22

• a = 9.4577 (4) Å

• c = 15.8301 (13) Å

• V = 1226.27 (7) ų

• Z = 6

• Mo Kα radiation

• μ = 2.99 mm⁻¹

• T = 296 K

• 0.17 × 0.10 × 0.10 mm

Data collection

• Bruker APEXII CCD detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1999) T_min = 0.705, T_max = 0.741

• 18120 measured reflections

• 1553 independent reflections

• 1517 reflections with I > 2σ(I)

• R_int = 0.031

Refinement

• R[F² > 2σ(F²)] = 0.037

• wR(F²) = 0.101

• S = 1.10

• 1553 reflections

• 76 parameters

• H-atom parameters constrained

• Δρ_max = 1.59 e Å⁻³

• Δρ_min = −1.56 e Å⁻³

• Absolute structure: Flack (1983), 543 Friedel pairs

• Flack parameter: −0.01 (5)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O6—H6A⋯O3^i	0.86	1.89	2.744 (3)	175
O5—H5A⋯O5^ii	0.86	2.06	2.889 (3)	162
O6—H6B⋯O2	0.86	1.93	2.781 (3)	170
Symmetry codes: (i) ; (ii) .

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; 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).

Supporting information

S1. Comment

The rich structural chemistry of the borophosphates system has generated considerable contemporary interest as a consequence of the interesting physical and chemical properties of the porous or tunnel structures generally adopted by the inorganic solids which are formed (Kniep et al., 1998, Ewald et al., 2007). Most of these compounds were synthesized with alkali (A^I) and transition metal cations (M^II), with the general formula A^IM^II(H₂O)₂[BP₂O₈].H₂O, under hydrothermal conditions at 443–463 K (Kniep et al. (1997) and Lin et al. (2008)).

The crystal structure of the new synthesized helical borophosphate-hydrate AgMg(H₂O)₂[BP₂O₈].H₂O is isotopic with other analogues borophosphates like A^IM^II (H₂O)₂[BP₂O₈].H₂O (A^I = Li, Na, K, NH₄⁺ and M^II = Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd) (Menezes et al., (2008)). Fig. 1 represents the plot of the asymmetric unit showing the cationic environment and the connection between different polyhedra. The BO₄ and PO₄ tetrahedra are relatively regular with B—O and P—O bond lengths ranging from 1.455 (3) Å to 1.480 (3) Å and from 1.503 (2) Å to to 1.569 (2) Å, respectively. Whereas, in the distorted MgO₄(H₂O)₂ octahedron, the distances Mg—O vary between 2.053 (2) Å and 2.169 (3) Å. Moreover, the AgO₆ polyhedron is more irregular with Ag—O distances in the range of 2.462–2.725 (3) Å.

The structure consists of infinite one dimensional helical anionic ribbons [BP₂O₈]^3- constructed by corner-sharing BO₄ and PO₄ tetrahedra, arranged around the 6₅ screw axes. The ribbons borders are connected with Mg²⁺ cations via the terminal oxygen atoms of the phosphate groups. A three dimensional network is formed by interconnection between the (AgO₆)_n helices running along [001] and the tetrahedral ribbons via the slightly distorted MgO₄(H₂O)₂ octahedra. The central channels of the helices, running along c axis, are filled up with the water molecule as shown in Fig 2. The structure is stabilized by O—H···O hydrogen bonds between water molecules and O atoms that are part of the helices (Table 1).

Related literature

For isotypic Mg analogues, see: Kniep et al. (1997); Lin et al. (2008). For other similar borophosphates, see: Kniep et al. (1998); Ewald et al. (2007); Menezes et al. (2008).

S2. Experimental

The compound was hydrothermally synthesized at 453 °K for 7 days in a 25 ml Teflon-lined steel autoclave from the mixture of MgO, H₃BO₃, H₃PO₄ (85%), AgNO₃ and 5 ml of distilled water in the molar ratio of 1:4:6:1:165. The brilliant colourless octahedral crystals were recovered and washed with hot water, then dried in air. Except for boron and hydrogen the presence of the elements were additionally confirmed by EDAX measurements.

S3. Refinement

The highest peak in the difference map is at 0.76 Å from Ag1 atom, and the minimum peak is at 0.52 Å from Ag1 atom.

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 AgMg(H2O)2[BP2O8] H2O crystal structure showing plyhedra 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 AgMg(H2O)2[BP2O8] H2O framework structure showing tunnel running along c direction where water molecules are located.

Silver(I) diaquamagnesium catena-borodiphosphate(V) monohydrate

Crystal data

AgMg(H2O)2[BP2O8]·H2O	Dx = 3.144 Mg m^−3
Mr = 386.98	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6522	Cell parameters from 1553 reflections
Hall symbol: P 65 2 ( 0 0 1)	θ = 2.5–33.0°
a = 9.4577 (4) Å	µ = 2.99 mm^−1
c = 15.8301 (13) Å	T = 296 K
V = 1226.27 (7) Å^3	Prism, colourless
Z = 6	0.17 × 0.10 × 0.10 mm
F(000) = 1128

Data collection

Bruker APEXII CCD detector diffractometer	1553 independent reflections
Radiation source: fine-focus sealed tube	1517 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ω and ϕ scans	θmax = 33.0°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1999)	h = −14→14
Tmin = 0.705, Tmax = 0.741	k = −14→13
18120 measured reflections	l = −24→24

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.037	w = 1/[σ^2(Fo^2) + (0.0472P)^2 + 4.7811P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.101	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 1.59 e Å^−3
1553 reflections	Δρmin = −1.56 e Å^−3
76 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0049 (7)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 543 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.01 (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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ag1	0.18579 (4)	0.81421 (4)	1.0833	0.03836 (17)
Mg	0.10244 (16)	0.55122 (8)	0.9167	0.0065 (2)
P1	0.16930 (8)	0.78125 (8)	0.75206 (4)	0.00471 (13)
B1	−0.1513 (2)	0.6974 (5)	0.7500	0.0052 (6)
O1	0.1362 (3)	0.6230 (3)	0.79151 (13)	0.0098 (4)
O2	0.3176 (3)	0.9319 (3)	0.78429 (13)	0.0103 (4)
O3	0.1801 (3)	0.7639 (3)	0.65405 (12)	0.0070 (3)
O4	0.0211 (2)	0.8082 (2)	0.76691 (12)	0.0067 (3)
O5	0.1244 (8)	1.0000	1.0000	0.082 (3)
H5A	0.0727	0.9715	1.0473	0.098*
O6	0.2931 (3)	0.7990 (3)	0.94403 (14)	0.0129 (4)
H6A	0.3869	0.8124	0.9579	0.016*
H6B	0.3096	0.8516	0.8974	0.016*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.0451 (3)	0.0451 (3)	0.0305 (3)	0.0267 (3)	−0.00288 (19)	−0.00288 (19)
Mg	0.0067 (5)	0.0063 (4)	0.0066 (5)	0.0034 (3)	0.000	0.0011 (4)
P1	0.0044 (2)	0.0053 (2)	0.0044 (2)	0.0023 (2)	0.0003 (2)	0.0011 (2)
B1	0.0057 (11)	0.0073 (14)	0.0030 (13)	0.0036 (7)	0.0004 (10)	0.000
O1	0.0145 (10)	0.0083 (9)	0.0072 (8)	0.0062 (7)	0.0010 (7)	0.0031 (7)
O2	0.0054 (8)	0.0108 (9)	0.0102 (8)	0.0008 (7)	−0.0015 (6)	−0.0002 (7)
O3	0.0103 (8)	0.0089 (8)	0.0038 (7)	0.0062 (7)	0.0009 (6)	0.0011 (6)
O4	0.0039 (7)	0.0065 (8)	0.0095 (8)	0.0023 (6)	−0.0015 (6)	−0.0025 (6)
O5	0.042 (2)	0.072 (5)	0.140 (8)	0.036 (3)	−0.033 (3)	−0.066 (6)
O6	0.0099 (9)	0.0136 (10)	0.0130 (9)	0.0041 (8)	−0.0003 (7)	0.0031 (7)

Geometric parameters (Å, º)

Ag1—O6^i	2.461 (2)	P1—O2	1.503 (2)
Ag1—O6	2.462 (2)	P1—O4	1.563 (2)
Ag1—O5	2.487 (4)	P1—O3	1.569 (2)
Ag1—O5^i	2.487 (4)	B1—O4	1.455 (3)
Ag1—Mg	3.4363 (4)	B1—O4^v	1.455 (3)
Ag1—Mg^i	3.4363 (4)	B1—O3^vi	1.480 (3)
Mg—O2^ii	2.053 (2)	B1—O3^ii	1.480 (3)
Mg—O2^iii	2.053 (2)	O2—Mg^vii	2.053 (2)
Mg—O1	2.067 (2)	O3—B1^vi	1.480 (3)
Mg—O1^iv	2.067 (2)	O5—Ag1^viii	2.487 (4)
Mg—O6	2.169 (3)	O5—H5A	0.8600
Mg—O6^iv	2.169 (3)	O6—H6A	0.8600
P1—O1	1.503 (2)	O6—H6B	0.8600
O6^i—Ag1—O6	131.89 (11)	O2^iii—Mg—O6^iv	89.01 (10)
O6^i—Ag1—O5	148.09 (10)	O1—Mg—O6^iv	83.08 (9)
O6—Ag1—O5	79.32 (11)	O1^iv—Mg—O6^iv	85.88 (9)
O6^i—Ag1—O5^i	79.32 (11)	O6—Mg—O6^iv	87.91 (14)
O6—Ag1—O5^i	148.09 (10)	O1—P1—O2	115.72 (13)
O5—Ag1—O5^i	71.0 (2)	O1—P1—O4	110.01 (12)
O2^ii—Mg—O2^iii	94.25 (15)	O2—P1—O4	106.40 (12)
O2^ii—Mg—O1	99.94 (9)	O1—P1—O3	107.40 (12)
O2^iii—Mg—O1	90.53 (9)	O2—P1—O3	110.86 (12)
O2^ii—Mg—O1^iv	90.53 (9)	O4—P1—O3	106.05 (11)
O2^iii—Mg—O1^iv	99.94 (9)	O4—B1—O4^v	102.9 (3)
O1—Mg—O1^iv	164.64 (15)	O4—B1—O3^vi	113.29 (11)
O2^ii—Mg—O6	89.01 (10)	O4^v—B1—O3^vi	112.88 (11)
O2^iii—Mg—O6	175.52 (10)	O4—B1—O3^ii	112.88 (11)
O1—Mg—O6	85.88 (9)	O4^v—B1—O3^ii	113.29 (11)
O1^iv—Mg—O6	83.08 (9)	O3^vi—B1—O3^ii	102.0 (3)
O2^ii—Mg—O6^iv	175.52 (10)	H6A—O6—H6B	104.9

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.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O6—H6A···O3^ix	0.86	1.89	2.744 (3)	175
O5—H5A···O5^i	0.86	2.06	2.889 (3)	162
O6—H6B···O2	0.86	1.93	2.781 (3)	170

Symmetry codes: (i) −y+1, −x+1, −z+13/6; (ix) −x+y, −x+1, z+1/3.