supplementary materials


cq2003 scheme

Acta Cryst. (2013). E69, m452-m453    [ doi:10.1107/S1600536813018722 ]

catena-Poly[[[tetraaquamagnesium]-trans-[mu]-[(piperazine-1,4-diium-1,4-diyl)bis(methylene)]diphosphonato] hemihydrate]

L.-H. Schilling and N. Stock

Abstract top

The structure of the title polymer, }[Mg(C6H14N2O6P2)(H2O)4]·0.5H2O}n, is based on centrosymmetric MgO6 octahedra, which are linked by [(piperazine-1,4-diium-1,4-diyl)bis(methylene)]diphosphonate ligands, forming chains parallel to [1-1-1]. These chains are connected via hydrogen bonds primarily formed between the phosphonate groups and water molecules. The latter constitute four of the corners of the MgO6 polyhedra and bind to the O atoms of the phosphonate groups of neighbouring chains. The lattice water molecule is disordered around an inversion centre, exhibiting an occupancy of 0.25.

Comment top

Due to their flexible coordination behaviour, organic linker molecules containing phosphonate groups allow the synthesis of a multitude of inorganic-organic hybrid materials (Gagnon et al., 2012). In this context, the ligand N,N'-piperazinebis(methylenephosphonic acid) (H2O3P—CH2—NC4H8N—CH2—PO3H2 = H4L) has been the subject of intense interest, since its use has led to a number of dense metal phosphonates (Groves, Stephens et al., 2006, Groves et al., 2005a, 2005b, Choi et al., 1994, LaDuca et al., 1996, Soghomonian et al., 1995, Wang et al., 2004) as well as porous ones (Groves, Miller et al., 2006, Serre et al., 2006). The compounds [Co2(H2O)2L] . 5.1 H2O (denoted Co-STA-12) and [Mg2(H2O)2L] . 3.97 H2O (denoted CAU-2) are highly porous with micropore volumes of 0.14 cm3 g-1 and 0.20 cm3 g-1, respectively (Wharmby et al., 2012). Investigation of the system MgCl2 . 6 H2O / H4L / base / H2O led to the formation of CAU-2. We have now been able to isolate a new compound, [Mg(H2O)4(H2L)] . 0.5 H2O, in this system, which is obtained from slightly acidic reaction mixtures (4 pH 6.5). Optimization of the reaction conditions (concentration and reaction time) led to the formation of single crystals. The asymmetric unit of the crystal structure is depicted in Fig. 1.

[Mg(H2O)4(H2L)] . 0.5 H2O adopts a one-dimensional structure containing alternating inorganic and organic building units of MgO6 polyhedra and N,N'-piperaziniumbis(methylenephosphonate) ions (Fig. 2). The Mg2+ ions are octahedrally coordinated by six oxygen atoms (O1, O4, O5 and their symmetry equivalents), of which four (O4 and O5) belong to water molecules while two (O1) belong to phosphonate groups of the ligand molecules. The charge of the structure is balanced by protons connected to the N atoms of the ligand making it a quaternary amine. In addition, a further water molecule is found on a partially occupied position.

Related literature top

For related magnesium structures, see: Wharmby et al. (2012). For related N,N'-piperaziniumbis(methylenephosphonates), see: Choi et al. (1994); Groves et al. (2005a,b); Groves, Stephens et al. (2006); Groves, Miller et al. (2006); LaDuca et al. (1996); Serre et al. (2006); Soghomonian et al. (1995); Wang et al. (2004); Wharmby et al. (2012). As a result of their flexible coordination behaviour, organic linker molecules containing phosphonate groups allow the synthesis of a multitude of inorganic-organic hybrid materials, see: Gagnon et al. (2012).

Experimental top

A reaction mixture of MgCl2 . 6 H2O (13.55 mg, 50 µmol), N,N'-piperazinebis(methylenephosphonic acid) (36.55 mg, 100 nmol), potassium hydroxide (16.83 mg, 300 nmol) and 1.5 ml water was placed in a 2 ml Teflon-lined autoclave. Subsequently the reactor was heated from room temperature to 130 °C (heating rate 1 °C min-1), the temperature was held for 52 h and then slowly lowered to room temperature over a period of 12 h. The resulting colourless crystals were collected by filtration and analysed via single-crystal XRD. Yield: 32%.

Refinement top

All H atoms of C—H groups were located in difference maps but were positioned with idealized geometry and were refined isotropically with Uiso(H) = 1.2 Ueq(C) using a riding model with C—H = 0.97 Å for aliphatic H atoms. The water H atoms were located in difference maps, their bond lengths were set to ideal values of 0.82 Å and they were refined using a riding model with Uiso(H) = 1.5 Ueq(O). The N—H H atom was located in a difference map but was positioned with idealized geometry and was refined isotropic with Uiso(H) = 1.2 Ueq(C) using a riding model with N—H = 0.86 Å.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2008); cell refinement: X-AREA (Stoe & Cie, 2008); data reduction: X-AREA (Stoe & Cie, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and DIAMOND Brandenburg (2011);; software used to prepare material for publication: XCIF in SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. : Asymmetric unit of the title compound with labeling and displacement ellipsoids drawn at the 50% probability level.
[Figure 2] Fig. 2. : Chain-formed building unit of [Mg(H2O)4(H2L)] . 0.5 H2O.
catena-Poly[[[tetraaquamagnesium]-trans-µ-[(piperazine-1,4-diium-1,4-diyl)bis(methylene)]diphosphonato] hemihydrate] top
Crystal data top
[Mg(C6H14N2O6P2)(H2O)4]·0.5H2OZ = 1
Mr = 377.51F(000) = 199
Triclinic, P1Dx = 1.714 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.6296 (5) ÅCell parameters from 1270 reflections
b = 6.8074 (6) Åθ = 1.2–29.8°
c = 8.7962 (7) ŵ = 0.40 mm1
α = 94.579 (6)°T = 293 K
β = 103.326 (6)°Needle, colorless
γ = 106.552 (6)°0.21 × 0.12 × 0.04 mm
V = 365.75 (5) Å3
Data collection top
Stoe IPSD-2
diffractometer
1957 independent reflections
Radiation source: fine-focus sealed tube1727 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.036
ω scanθmax = 29.2°, θmin = 3.2°
Absorption correction: numerical
(X-SHAPE and X-RED32; Stoe & Cie, 2008)
h = 99
Tmin = 0.886, Tmax = 0.974k = 99
6973 measured reflectionsl = 1212
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.080H-atom parameters constrained
S = 1.01 w = 1/[σ2(Fo2) + (0.0352P)2 + 0.2734P]
where P = (Fo2 + 2Fc2)/3
1957 reflections(Δ/σ)max < 0.001
103 parametersΔρmax = 0.43 e Å3
0 restraintsΔρmin = 0.43 e Å3
Crystal data top
[Mg(C6H14N2O6P2)(H2O)4]·0.5H2Oγ = 106.552 (6)°
Mr = 377.51V = 365.75 (5) Å3
Triclinic, P1Z = 1
a = 6.6296 (5) ÅMo Kα radiation
b = 6.8074 (6) ŵ = 0.40 mm1
c = 8.7962 (7) ÅT = 293 K
α = 94.579 (6)°0.21 × 0.12 × 0.04 mm
β = 103.326 (6)°
Data collection top
Stoe IPSD-2
diffractometer
1727 reflections with I > 2σ(I)
Absorption correction: numerical
(X-SHAPE and X-RED32; Stoe & Cie, 2008)
Rint = 0.036
Tmin = 0.886, Tmax = 0.974θmax = 29.2°
6973 measured reflectionsStandard reflections: 0
1957 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.080Δρmax = 0.43 e Å3
S = 1.01Δρmin = 0.43 e Å3
1957 reflectionsAbsolute structure: ?
103 parametersAbsolute structure parameter: ?
0 restraintsRogers parameter: ?
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)
Mg10.50000.50000.50000.01868 (16)
P10.36611 (6)0.83891 (6)0.71790 (4)0.01741 (10)
O10.47100 (19)0.67534 (18)0.69031 (14)0.0256 (2)
O20.22643 (18)0.87610 (17)0.56605 (13)0.0228 (2)
O30.52336 (14)1.04094 (13)0.81824 (11)0.0225 (2)
C10.17809 (14)0.73201 (13)0.83666 (11)0.0218 (3)
H1A0.22640.62790.89040.026*
H1B0.03790.62400.80340.026*
N10.1348 (2)0.89184 (19)0.94153 (15)0.0181 (2)
H1N10.25890.95581.00770.022*
C20.0614 (3)1.0529 (2)0.85892 (19)0.0235 (3)
H2A0.07540.98700.77910.028*
H2B0.16901.12250.80650.028*
C30.0313 (3)0.7900 (2)1.02369 (19)0.0218 (3)
H3A0.01470.68571.07860.026*
H3B0.16950.72110.94610.026*
O40.30950 (18)0.64149 (17)0.34463 (13)0.0236 (2)
H1O40.37780.72910.30080.028*
H2O40.26470.71530.39800.028*
O50.22487 (19)0.26098 (18)0.51161 (16)0.0309 (3)
H1O50.23830.14880.53100.037*
H2O50.09570.25400.49220.037*
O60.5116 (13)0.5606 (12)1.0711 (9)0.0620 (19)0.25
H1O60.52840.51201.15380.093*0.25
H2O60.52050.68221.09560.093*0.25
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mg10.0172 (3)0.0181 (3)0.0219 (3)0.0073 (3)0.0059 (3)0.0011 (3)
P10.01580 (17)0.01772 (18)0.01999 (19)0.00653 (13)0.00637 (13)0.00069 (13)
O10.0300 (6)0.0285 (6)0.0246 (6)0.0176 (5)0.0094 (5)0.0020 (4)
O20.0203 (5)0.0246 (5)0.0244 (5)0.0097 (4)0.0047 (4)0.0025 (4)
O30.0200 (5)0.0213 (5)0.0237 (5)0.0037 (4)0.0053 (4)0.0010 (4)
C10.0228 (7)0.0170 (6)0.0276 (8)0.0055 (5)0.0121 (6)0.0011 (6)
N10.0151 (5)0.0194 (6)0.0206 (6)0.0052 (4)0.0070 (5)0.0019 (5)
C20.0269 (7)0.0258 (7)0.0246 (7)0.0132 (6)0.0127 (6)0.0077 (6)
C30.0216 (7)0.0205 (7)0.0271 (7)0.0066 (6)0.0129 (6)0.0060 (6)
O40.0245 (5)0.0233 (5)0.0252 (6)0.0101 (4)0.0075 (4)0.0032 (4)
O50.0186 (5)0.0240 (6)0.0501 (8)0.0059 (4)0.0086 (5)0.0106 (5)
O60.065 (5)0.059 (4)0.068 (5)0.025 (4)0.019 (4)0.020 (4)
Geometric parameters (Å, º) top
Mg1—O1i2.0552 (11)N1—H1N10.8600
Mg1—O12.0553 (11)C2—C3ii1.513 (2)
Mg1—O52.0991 (12)C2—H2A0.9700
Mg1—O5i2.0992 (12)C2—H2B0.9700
Mg1—O4i2.1209 (11)C3—C2ii1.513 (2)
Mg1—O42.1209 (11)C3—H3A0.9700
P1—O11.5027 (11)C3—H3B0.9700
P1—O21.5242 (12)O4—H1O40.8199
P1—O31.5240 (10)O4—H2O40.8201
P1—C11.8383O5—H1O50.8200
C1—N11.5022 (15)O5—H2O50.8200
C1—H1A0.9700O6—O6iii1.395 (16)
C1—H1B0.9700O6—H1O60.8201
N1—C31.4925 (18)O6—H2O60.8200
N1—C21.495 (2)
O1i—Mg1—O1180.00 (6)C3—N1—C2108.49 (11)
O1i—Mg1—O590.35 (5)C3—N1—C1110.46 (10)
O1—Mg1—O589.65 (5)C2—N1—C1114.75 (11)
O1i—Mg1—O5i89.65 (5)C3—N1—H1N1111.5
O1—Mg1—O5i90.35 (5)C2—N1—H1N1106.5
O5—Mg1—O5i180.00 (7)C1—N1—H1N1105.1
O1i—Mg1—O4i89.80 (4)N1—C2—C3ii110.27 (12)
O1—Mg1—O4i90.20 (4)N1—C2—H2A109.6
O5—Mg1—O4i87.19 (5)C3ii—C2—H2A109.6
O5i—Mg1—O4i92.81 (5)N1—C2—H2B109.6
O1i—Mg1—O490.20 (4)C3ii—C2—H2B109.6
O1—Mg1—O489.80 (4)H2A—C2—H2B108.1
O5—Mg1—O492.81 (5)N1—C3—C2ii111.06 (12)
O5i—Mg1—O487.19 (5)N1—C3—H3A109.4
O4i—Mg1—O4180.0C2ii—C3—H3A109.4
O1—P1—O2113.06 (7)N1—C3—H3B109.4
O1—P1—O3114.25 (6)C2ii—C3—H3B109.4
O2—P1—O3112.00 (6)H3A—C3—H3B108.0
O1—P1—C1105.10 (6)Mg1—O4—H1O4115.4
O2—P1—C1106.31 (6)Mg1—O4—H2O4108.1
O3—P1—C1105.20 (5)H1O4—O4—H2O499.6
P1—O1—Mg1137.40 (7)Mg1—O5—H1O5119.2
N1—C1—P1114.69 (7)Mg1—O5—H2O5130.9
N1—C1—H1A114.7H1O5—O5—H2O5109.7
P1—C1—H1A108.7O6iii—O6—H1O6119.9
N1—C1—H1B102.6O6iii—O6—H2O6133.7
P1—C1—H1B128.8H1O6—O6—H2O6106.3
H1A—C1—H1B83.9
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+2, z+2; (iii) x+1, y+1, z+2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N1···O3iv0.861.842.6187 (16)150
O4—H1O4···O3v0.821.992.7956 (15)166
O4—H2O4···O20.821.882.6733 (17)164
O5—H1O5···O2vi0.821.892.7032 (17)172
O5—H2O5···O2vii0.821.992.7667 (18)158
C1—H1B···O4vii0.972.483.4279 (15)166
C2—H2B···O30.972.553.187 (2)124
Symmetry codes: (iv) x+1, y+2, z+2; (v) x+1, y+2, z+1; (vi) x, y1, z; (vii) x, y+1, z+1.

Experimental details

Crystal data
Chemical formula[Mg(C6H14N2O6P2)(H2O)4]·0.5H2O
Mr377.51
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)6.6296 (5), 6.8074 (6), 8.7962 (7)
α, β, γ (°)94.579 (6), 103.326 (6), 106.552 (6)
V3)365.75 (5)
Z1
Radiation typeMo Kα
µ (mm1)0.40
Crystal size (mm)0.21 × 0.12 × 0.04
Data collection
DiffractometerStoe IPSD-2
diffractometer
Absorption correctionNumerical
(X-SHAPE and X-RED32; Stoe & Cie, 2008)
Tmin, Tmax0.886, 0.974
No. of measured, independent and
observed [I > 2σ(I)] reflections
6973, 1957, 1727
Rint0.036
(sin θ/λ)max1)0.686
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.080, 1.01
No. of reflections1957
No. of parameters103
No. of restraints0
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.43, 0.43

Computer programs: X-AREA (Stoe & Cie, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008) and DIAMOND Brandenburg (2011);, XCIF in SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N1···O3i0.861.842.6187 (16)150
O4—H1O4···O3ii0.821.992.7956 (15)166
O4—H2O4···O20.821.882.6733 (17)164
O5—H1O5···O2iii0.821.892.7032 (17)172
O5—H2O5···O2iv0.821.992.7667 (18)158
C1—H1B···O4iv0.972.483.4279 (15)166
C2—H2B···O30.972.553.187 (2)124
Symmetry codes: (i) x+1, y+2, z+2; (ii) x+1, y+2, z+1; (iii) x, y1, z; (iv) x, y+1, z+1.
Acknowledgements top

We gratefully acknowledge financial support by the DFG (project No. STO-643/2–3) and the State of Schleswig–Holstein.

references
References top

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