A second polymorph with composition Co₃(PO₄)₂·H₂O

Abstract

Single crystals of Co₃(PO₄)₂·H₂O, tricobalt(II) bis­[ortho­phosphate(V)] monohydrate, were obtained under hydro­thermal conditions. The compound is the second polymorph of this composition and is isotypic with its zinc analogue, Zn₃(PO₄)₂·H₂O. Three independent Co²⁺ cations are bridged by two independent orthophosphate anions. Two of the metal cations exhibit a distorted tetra­hedral coordination while the third exhibits a considerably distorted [5 + 1] octa­hedral coordination environment with one very long Co—O distance of 2.416 (3) Å. The former cations are bonded to four different phosphate anions, and the latter cation is bonded to four anions (one of which is bidentate) and one water mol­ecule, leading to a framework structure. Additional hydrogen bonds of the type O—H⋯O stabilize this arrangement.

Related literature

Besides crystals of the title compound, crystals of the related phase Co₃(PO₄)₂·4H₂O (Lee et al., 2008 ▶) were also obtained under hydro­thermal conditions. For a review of metal complexes of organophosphate esters and open-framework metal phosphates, see: Murugavel et al. (2008 ▶). For different cobalt(II) phosphates, see: Mellor (1935 ▶). The first polymorph of composition Co₃(PO₄)₂·H₂O was reported by Anderson et al. (1976 ▶), and the crystal structure of the isotypic Zn analogue Zn₃(PO₄)₂·H₂O was described by Riou et al. (1986 ▶).

Experimental

Crystal data

• Co₃(PO₄)₂·H₂O

• M _r = 384.75

• Monoclinic,

• a = 8.7038 (15) Å

• b = 4.8667 (9) Å

• c = 16.705 (3) Å

• β = 95.670 (3)°

• V = 704.1 (2) ų

• Z = 4

• Mo Kα radiation

• μ = 7.47 mm⁻¹

• T = 150 (2) K

• 0.46 × 0.14 × 0.08 mm

Data collection

• Siemens SMART 1000 CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1999 ▶) T _min = 0.247, T _max = 0.554

• 6569 measured reflections

• 1697 independent reflections

• 1603 reflections with I > 2σ(I)

• R _int = 0.026

Refinement

• R[F ² > 2σ(F ²)] = 0.033

• wR(F ²) = 0.095

• S = 1.07

• 1697 reflections

• 133 parameters

• 2 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.73 e Å⁻³

• Δρ_min = −1.39 e Å⁻³

Data collection: SMART (Siemens, 1995 ▶); cell refinement: SAINT (Siemens, 1995 ▶); data reduction: SAINT and XPREP (Siemens, 1995 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶), WebLab ViewerPro (Molecular Simulations, 2000 ▶) and POV-RAY (Cason, 2002 ▶).; software used to prepare material for publication: enCIFer (Allen et al., 2004 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Co1—O3	1.897 (3)
Co1—O4	1.941 (3)
Co1—O2	1.992 (3)
Co1—O1	2.002 (3)
Co2—O9	1.887 (3)
Co2—O5	1.949 (3)
Co2—O1	1.986 (3)
Co2—O2i	2.054 (3)
Co3—O6	2.019 (3)
Co3—O7	2.061 (3)
Co3—O8	2.065 (3)
Co3—O8ii	2.075 (3)
Co3—O5iii	2.108 (3)
Co3—O3iv	2.416 (3)
P1—O6	1.513 (3)
P1—O4i	1.534 (3)
P1—O2v	1.560 (3)
P1—O1	1.561 (3)
P2—O9	1.511 (3)
P2—O8vi	1.544 (3)
P2—O3vii	1.549 (3)
P2—O5vi	1.565 (3)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H2⋯O6iii	0.90 (3)	1.86 (4)	2.753 (4)	170 (5)
O7—H1⋯O4viii	0.903 (10)	1.864 (15)	2.758 (4)	171 (5)

Symmetry codes: (iii) ; (viii) .

supplementary crystallographic information

Comment

Synthesis and structural investigations of transition-metal phosphates under various conditions, including high temperature and high pressure, have been investigated for many years (Murugavel et al., 2008). This is not only because of the multifarious structural chemistry, but also due to many potential applications. For a listing of reviews on these materials, see Lee et al. (2008). We are currently investigating the synthesis of a variety of similar functional materials through templation effects under hydrothermal conditions. The title compound, Co₃(PO₄)₂.H₂O, (I), and the related compound Co₃(PO₄)₂.4H₂O (Lee et al., 2008) were synthesized as a part of these studies.

In the past, many different cobalt(II) orthophosphates have been described, ranging from the anhydrous form Co₃(PO₄)₂ to its corresponding octahydrate (Mellor, 1935). In 1976 Anderson et al. reported a first polymorph of Co₃(PO₄)₂.H₂O formed under high pressure conditions. The second polymorph of Co₃(PO₄)₂.H₂O presented here has a different unit cell and a considerably different cell volume (638.3 (Anderson et al., 1976) versus 704.1 ų (this study)) and exhibits also a different assembly of the structural building units. The second polymorph (I) is isotypic with its Zn analogue Zn₃(PO₄)₂.H₂O (Riou et al., 1986).

The structure of (I) contains three different Co²⁺ centres bridged by orthophosphate anions (Fig 1). The coordination spheres of Co1 and Co2 are distorted tetrahedral while that of Co3 is distorted octahedral, with one considerably longer Co—O bond of 2.416 (3) Å (Table 1). Co1 and Co2 are bonded to the O atoms of four phosphate ligands, whereas Co3 is bonded to five O atoms of four phosphate ligands (one bidentate) and the sixth coordination site is occupied by a water molecule. This assembly leads to the formation of a three-dimensional framework (Fig. 2), which is stabilized by additional O—H···O hydrogen bonds (Table 2).

Experimental

Conditions of the hydrothermal single crystal growth of the hydrous cobalt(II) orthophosphates Co₃(PO₄)₂.H₂O and Co₃(PO₄)₂.4 H₂O were described in detail in a preceding communication (Lee et al., 2008).

Refinement

Water H atoms were located in difference Fourier maps and were refined with U_iso(H) values fixed at 1.5U_eq of the parent O atoms. O—H bond length restraints of 0.89 (1) Å were also employed. The highest peak and the deepest hole in the final Fourier map are located 1.74 Å from O1 and 0.20 Å from P1, respectively.

Figures

Fig. 1.

The asymmetric unit of compound (I), drawn with displacement parameters at the 50% probability level. H atoms are given as spheres of arbitrary radius.

Fig. 2.

A schematic representation of a section of the three-dimensional network of (I) in a projection along [010]. Hydrogen atoms are omitted for clarity.

Crystal data

Co3(PO4)2·H2O	F(000) = 740
Mr = 384.75	Dx = 3.629 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4684 reflections
a = 8.7038 (15) Å	θ = 2.5–28.4°
b = 4.8667 (9) Å	µ = 7.47 mm−1
c = 16.705 (3) Å	T = 150 K
β = 95.670 (3)°	Plate, purple
V = 704.1 (2) Å3	0.46 × 0.14 × 0.08 mm
Z = 4

Data collection

Siemens SMART 1000 CCD diffractometer	1697 independent reflections
Radiation source: sealed tube	1603 reflections with I > 2σ(I)
graphite	Rint = 0.026
ω scans	θmax = 28.4°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1999)	h = −11→11
Tmin = 0.247, Tmax = 0.554	k = −6→6
6569 measured reflections	l = −21→21

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033	Hydrogen site location: difference Fourier map
wR(F2) = 0.095	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ2(Fo2) + (0.0597P)2 + 3.2629P] where P = (Fo2 + 2Fc2)/3
1697 reflections	(Δ/σ)max < 0.001
133 parameters	Δρmax = 0.74 e Å−3
2 restraints	Δρmin = −1.39 e Å−3

Special details

Experimental. The crystal was coated in Exxon Paratone N hydrocarbon oil and mounted on a thin mohair fibre attached to a copper pin. Upon mounting on the diffractometer, the crystal was quenched to 150(K) under a cold nitrogen gas stream supplied by an Oxford Cryosystems Cryostream.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
Co1	0.32855 (5)	0.20270 (9)	0.94291 (3)	0.00253 (14)
Co2	0.56640 (5)	−0.20252 (9)	0.84576 (3)	0.00303 (15)
Co3	0.92910 (6)	0.49852 (10)	0.82254 (3)	0.00814 (16)
P1	0.68190 (11)	0.29320 (19)	0.94510 (6)	0.0086 (2)
P2	0.23599 (11)	−0.51187 (19)	0.78087 (6)	0.0087 (2)
O1	0.5357 (3)	0.1481 (6)	0.90286 (17)	0.0114 (5)
O2	0.3621 (3)	0.3976 (6)	1.04804 (16)	0.0106 (5)
O3	0.1907 (3)	0.3427 (6)	0.85760 (17)	0.0119 (5)
O4	0.2836 (3)	−0.1747 (6)	0.96996 (17)	0.0121 (6)
O5	0.7445 (3)	−0.2368 (6)	0.78428 (17)	0.0116 (5)
O6	0.8153 (3)	0.2545 (6)	0.89463 (17)	0.0120 (5)
O7	0.9749 (4)	0.7679 (6)	0.91711 (18)	0.0137 (6)
O8	0.9060 (3)	0.1703 (6)	0.74391 (17)	0.0108 (5)
O9	0.3852 (3)	−0.3512 (6)	0.79103 (18)	0.0148 (6)
H1	1.0769 (18)	0.797 (12)	0.929 (3)	0.022*
H2	0.933 (6)	0.936 (5)	0.909 (3)	0.022*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Co1	0.0013 (2)	0.0038 (2)	0.0025 (2)	0.00007 (15)	−0.00013 (17)	0.00053 (15)
Co2	0.0006 (2)	0.0045 (3)	0.0040 (2)	−0.00041 (15)	0.00015 (17)	−0.00098 (15)
Co3	0.0077 (3)	0.0083 (3)	0.0088 (3)	−0.00123 (17)	0.00306 (19)	−0.00064 (17)
P1	0.0070 (5)	0.0090 (5)	0.0098 (5)	−0.0004 (3)	0.0014 (3)	−0.0002 (3)
P2	0.0067 (5)	0.0103 (4)	0.0091 (4)	0.0003 (3)	0.0008 (3)	0.0001 (3)
O1	0.0101 (13)	0.0112 (12)	0.0129 (13)	−0.0009 (10)	0.0004 (10)	−0.0005 (10)
O2	0.0114 (13)	0.0106 (13)	0.0099 (13)	0.0026 (10)	0.0011 (10)	−0.0003 (10)
O3	0.0121 (13)	0.0133 (13)	0.0102 (13)	−0.0003 (11)	0.0007 (11)	0.0014 (10)
O4	0.0135 (14)	0.0116 (13)	0.0110 (13)	−0.0005 (10)	−0.0004 (11)	0.0009 (10)
O5	0.0108 (14)	0.0131 (12)	0.0114 (13)	0.0007 (10)	0.0041 (10)	0.0008 (10)
O6	0.0106 (14)	0.0132 (12)	0.0127 (13)	−0.0009 (11)	0.0035 (11)	0.0007 (10)
O7	0.0110 (14)	0.0132 (13)	0.0164 (14)	0.0012 (11)	−0.0014 (11)	−0.0015 (11)
O8	0.0075 (13)	0.0122 (13)	0.0131 (13)	−0.0006 (10)	0.0026 (10)	−0.0022 (10)
O9	0.0109 (14)	0.0163 (13)	0.0171 (14)	−0.0033 (11)	0.0012 (11)	−0.0011 (11)

Geometric parameters (Å, °)

Co1—O3	1.897 (3)	Co3—O3iv	2.416 (3)
Co1—O4	1.941 (3)	Co3—P2v	2.8266 (12)
Co1—O2	1.992 (3)	P1—O6	1.513 (3)
Co1—O1	2.002 (3)	P1—O4i	1.534 (3)
Co2—O9	1.887 (3)	P1—O2vi	1.560 (3)
Co2—O5	1.949 (3)	P1—O1	1.561 (3)
Co2—O1	1.986 (3)	P2—O9	1.511 (3)
Co2—O2i	2.054 (3)	P2—O8vii	1.544 (3)
Co3—O6	2.019 (3)	P2—O3viii	1.549 (3)
Co3—O7	2.061 (3)	P2—O5vii	1.565 (3)
Co3—O8	2.065 (3)	P2—Co3ix	2.8266 (12)
Co3—O8ii	2.075 (3)	O7—H1	0.903 (10)
Co3—O5iii	2.108 (3)	O7—H2	0.90 (3)
O3—Co1—O4	112.81 (13)	O4i—P1—O2vi	108.77 (15)
O3—Co1—O2	121.22 (12)	O6—P1—O1	109.15 (16)
O4—Co1—O2	105.11 (12)	O4i—P1—O1	108.94 (16)
O3—Co1—O1	108.70 (12)	O2vi—P1—O1	105.94 (16)
O4—Co1—O1	99.28 (12)	O9—P2—O8vii	112.91 (17)
O2—Co1—O1	107.42 (12)	O9—P2—O3viii	115.46 (17)
O9—Co2—O5	112.44 (13)	O8vii—P2—O3viii	102.81 (16)
O9—Co2—O1	114.62 (13)	O9—P2—O5vii	106.80 (16)
O5—Co2—O1	118.58 (12)	O8vii—P2—O5vii	110.75 (16)
O9—Co2—O2i	114.12 (12)	O3viii—P2—O5vii	108.04 (16)
O5—Co2—O2i	103.10 (12)	O9—P2—Co3ix	141.79 (13)
O1—Co2—O2i	91.48 (11)	O8vii—P2—Co3ix	45.96 (10)
O6—Co3—O7	89.20 (12)	O3viii—P2—Co3ix	58.69 (11)
O6—Co3—O8	84.37 (11)	O5vii—P2—Co3ix	110.73 (12)
O7—Co3—O8	168.15 (12)	P1—O1—Co2	117.61 (16)
O6—Co3—O8ii	164.15 (12)	P1—O1—Co1	120.63 (16)
O7—Co3—O8ii	93.56 (12)	Co2—O1—Co1	116.29 (14)
O8—Co3—O8ii	90.02 (7)	P1vi—O2—Co1	120.56 (16)
O6—Co3—O5iii	97.82 (11)	P1vi—O2—Co2i	115.98 (15)
O7—Co3—O5iii	85.85 (12)	Co1—O2—Co2i	123.17 (15)
O8—Co3—O5iii	104.85 (11)	P2iii—O3—Co1	126.29 (18)
O8ii—Co3—O5iii	97.95 (11)	P1i—O4—Co1	123.07 (17)
O6—Co3—O3iv	100.18 (11)	P2x—O5—Co2	116.94 (17)
O7—Co3—O3iv	84.70 (11)	P2x—O5—Co3viii	120.43 (16)
O8—Co3—O3iv	86.65 (10)	Co2—O5—Co3viii	120.96 (14)
O8ii—Co3—O3iv	64.61 (10)	P1—O6—Co3	135.08 (18)
O5iii—Co3—O3iv	159.51 (11)	Co3—O7—H1	113 (4)
O6—Co3—P2v	131.88 (9)	Co3—O7—H2	115 (4)
O7—Co3—P2v	94.83 (9)	H1—O7—H2	105 (5)
O8—Co3—P2v	82.21 (8)	P2x—O8—Co3	129.77 (16)
O8ii—Co3—P2v	32.34 (8)	P2x—O8—Co3xi	101.70 (14)
O5iii—Co3—P2v	130.28 (8)	Co3—O8—Co3xi	128.53 (14)
O6—P1—O4i	112.20 (17)	P2—O9—Co2	157.0 (2)
O6—P1—O2vi	111.63 (16)
O6—P1—O1—Co2	36.4 (2)	O1—Co2—O5—P2x	−54.5 (2)
O4i—P1—O1—Co2	−86.41 (19)	O2i—Co2—O5—P2x	−153.51 (18)
O2vi—P1—O1—Co2	156.73 (16)	O9—Co2—O5—Co3viii	−111.58 (17)
O6—P1—O1—Co1	−170.63 (17)	O1—Co2—O5—Co3viii	110.83 (17)
O4i—P1—O1—Co1	66.5 (2)	O2i—Co2—O5—Co3viii	11.79 (18)
O2vi—P1—O1—Co1	−50.3 (2)	O4i—P1—O6—Co3	−132.6 (2)
O9—Co2—O1—P1	−176.28 (16)	O2vi—P1—O6—Co3	−10.2 (3)
O5—Co2—O1—P1	−39.6 (2)	O1—P1—O6—Co3	106.6 (3)
O2i—Co2—O1—P1	66.23 (18)	O7—Co3—O6—P1	55.9 (3)
O9—Co2—O1—Co1	29.6 (2)	O8—Co3—O6—P1	−134.0 (3)
O5—Co2—O1—Co1	166.29 (13)	O8ii—Co3—O6—P1	156.2 (3)
O2i—Co2—O1—Co1	−87.91 (15)	O5iii—Co3—O6—P1	−29.8 (3)
O3—Co1—O1—P1	122.72 (19)	P2v—Co3—O6—P1	151.72 (19)
O4—Co1—O1—P1	−119.25 (19)	O6—Co3—O8—P2x	44.9 (2)
O2—Co1—O1—P1	−10.1 (2)	O7—Co3—O8—P2x	102.3 (6)
O3—Co1—O1—Co2	−83.97 (17)	O8ii—Co3—O8—P2x	−150.0 (2)
O4—Co1—O1—Co2	34.06 (16)	O5iii—Co3—O8—P2x	−51.7 (2)
O2—Co1—O1—Co2	143.21 (14)	P2v—Co3—O8—P2x	178.6 (2)
O3—Co1—O2—P1vi	−18.9 (2)	O6—Co3—O8—Co3xi	−134.86 (19)
O4—Co1—O2—P1vi	−148.23 (18)	O7—Co3—O8—Co3xi	−77.4 (6)
O1—Co1—O2—P1vi	106.71 (19)	O8ii—Co3—O8—Co3xi	30.29 (16)
O3—Co1—O2—Co2i	154.62 (15)	O5iii—Co3—O8—Co3xi	128.52 (17)
O4—Co1—O2—Co2i	25.34 (19)	P2v—Co3—O8—Co3xi	−1.19 (16)
O1—Co1—O2—Co2i	−79.72 (18)	O8vii—P2—O9—Co2	116.3 (5)
O4—Co1—O3—P2iii	−129.2 (2)	O3viii—P2—O9—Co2	−1.5 (6)
O2—Co1—O3—P2iii	105.0 (2)	O5vii—P2—O9—Co2	−121.7 (5)
O1—Co1—O3—P2iii	−20.1 (2)	Co3ix—P2—O9—Co2	69.4 (6)
O3—Co1—O4—P1i	−150.21 (19)	O5—Co2—O9—P2	137.1 (5)
O2—Co1—O4—P1i	−16.1 (2)	O1—Co2—O9—P2	−83.5 (6)
O1—Co1—O4—P1i	94.9 (2)	O2i—Co2—O9—P2	20.1 (6)
O9—Co2—O5—P2x	83.1 (2)

Symmetry codes: (i) −x+1, −y, −z+2; (ii) −x+2, y+1/2, −z+3/2; (iii) x, y+1, z; (iv) x+1, y, z; (v) x+1, y+1, z; (vi) −x+1, −y+1, −z+2; (vii) −x+1, y−1/2, −z+3/2; (viii) x, y−1, z; (ix) x−1, y−1, z; (x) −x+1, y+1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O7—H2···O6iii	0.90 (3)	1.86 (4)	2.753 (4)	170 (5)
O7—H1···O4v	0.90 (1)	1.86 (2)	2.758 (4)	171 (5)

Symmetry codes: (iii) x, y+1, z; (v) x+1, y+1, z.