Copper(II) hydrogenphosphate, CuHPO₄

Abstract

The title compound, CuHPO₄, has been synthesized from a mixture of phospho­ric acid and copper oxide. It has the same composition as MHPO₄ (M = Ca, Ba, Pb, Sr or Sn), but adopts a rhombohedral structure with all atoms on general positions. The structure features distorted PO₄ tetra­hedra linked by copper, forming 12-membered rings. The Cu^II atom is coordinated by five O atoms in a distorted square-pyramidal manner. O—H⋯O hydrogen bonding leads to an additional stabilization of the structure.

Related literature

For the structure of CaHPO₄, see: Smith et al. (1955 ▶); MacLennan & Beevers (1955 ▶). For a report about BaHPO₄ and PbHPO₄, see: Bengtsson (1941 ▶). For the structure of SnHPO₄, see: Berndt & Lamberg (1971 ▶). For information about SrHPO₄, see: Boudjada et al. (1978 ▶). For a report about CuHPO₄·H₂O, see: Boudjada (1980 ▶). For information about CuHPO₄·0.5 H₂O see: Sierra et al. (2003 ▶). For the structure of α-Cu₂P₂O₇, see: Lukaszewicz (1966 ▶). For information about β-Cu₂P₂O₇, see: Robertson & Calvo (1968 ▶). For a report about Cu₂P₄O₁₂, see: Laügt et al. (1972 ▶).

Experimental

Crystal data

• CuHPO₄

• M _r = 159.52

• Rhombohedral,

• a = 9.5145 (4) Å

• α = 114.678 (2)°

• V = 495.88 (6) ų

• Z = 6

• Mo Kα radiation

• μ = 6.92 mm⁻¹

• T = 183 K

• 0.05 × 0.03 × 0.03 mm

Data collection

• Nonius KappaCCD diffractometer

• Absorption correction: none

• 3338 measured reflections

• 755 independent reflections

• 654 reflections with I > 2σ(I)

• R _int = 0.045

Refinement

• R[F ² > 2σ(F ²)] = 0.026

• wR(F ²) = 0.066

• S = 1.02

• 755 reflections

• 60 parameters

• All H-atom parameters refined

• Δρ_max = 0.62 e Å⁻³

• Δρ_min = −0.66 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: DENZO (Otwinowski & Minor 1997 ▶); data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

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

Table 1. Selected bond lengths (Å).

Cu1—O1	1.925 (2)
Cu1—O4i	1.932 (2)
Cu1—O3ii	1.971 (2)
Cu1—O3iii	1.992 (2)
Cu1—O4iv	2.360 (2)
P1—O4	1.515 (2)
P1—O1	1.530 (2)
P1—O3	1.541 (2)
P1—O2	1.571 (2)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1ii	0.87 (5)	1.93 (5)	2.800 (3)	176 (5)

Symmetry code: (ii) .

supplementary crystallographic information

Comment

The hydrogen phosphate of copper(II) adopts the formula MHPO₄ like other divalent cations. However, the monetites CaHPO₄ (triclinic, P1; Smith et al., 1955), BaHPO₄ (orthorhombic, Pccn; Bengtsson, 1941) and PbHPO₄ (monoclinic, P2/c or Pc; Bengtsson, 1941) or SrHPO₄ (triclinic, P1; Boudjada et al., 1978) and SnHPO₄ (monoclinic, P2₁/c; Berndt & Lamberg, 1971) have very different structures, which could be due to the much bigger ionic radii of the metals in comparison to copper. CuHPO₄ has a rhombohedral (R3) structure. The coordination of Cu can be described as a square pyramid, with the apical C–O bond being significantly longer than the other four bonds. The coordination in the base plane could even be described as a strongly squeezed, almost planar tetrahedron (Fig 1). The Cu ions are linked by distorted PO₄ tetrahedra yielding twelve-membered rings (see Fig. 4, and Fig. 5). The distortion of the phosphate tetrahedra is caused by the OH-groups, which point towards the centre of the rings. There is only one hydrogen bond present in the asymmetric unit (see hydrogen bond geometry). But in the whole crystal structure, this leads to two intramolecular and three intermolecular hydrogen bonds (see Fig. 2 and Fig. 3). In other copper phosphates, the copper atoms are coordinated by four, five and/or six oxygen atoms, respectively (Boudjada, 1980; Sierra et al., 2003; Lukaszewicz, 1966; Robertson & Calvo, 1968; Laügt et al., 1972). CuHPO₄ formed only trigonal bipyramids of CuO₅.

Experimental

Phosphoric acid (65%) and copper oxide were mixed in a mortar for several hours. Afterwards the mixture was tempered at 373 K for a week. CuHPO₄ was obtained in the form of emerald-green needles, which decompose by further tempering.

Refinement

The hydrogen atom of the hydroxyd-group was located by difference Fourier synthesis and refined isotropically.

Figures

Fig. 1.

The molecular structure of 1, showing 50% probability displacement ellipsoides and the numbering scheme for the complete coordination polyhedron about Cu1 (Symmetry codes: (A) z,x-1,y-1; (B) -z+2,-x+2,-y+1; (C) -x+2,-y+1,-z+1 and (D) y,z,x-1.)

Fig. 2.

The intra and inter molecular O2—H2···O1 bonding about Cu1 (Symmetry codes: (A) z,x-1,y; (B) y+1,z,x-1 and (C) -y+1,-z+1,-x+1.)

Fig. 3.

The intra and inter molecular O2—H2···O1 bonding about Cu1 (Symmetry codes: (A) z,x-1,y; (B) y+1,z,x-1 and (C) -y+1,-z+1,-x+1.)

Fig. 4.

View of the unit cell of CuHPO~4~ along the z axis.

Fig. 5.

Projection of the CuHPO4 structure along the z axis, with applied polyhedrale.

Crystal data

CuHPO4	Dx = 3.205 Mg m−3
Mr = 159.52	Mo Kα radiation, λ = 0.71073 Å
Rhombohedral, R3	Cell parameters from 3338 reflections
Hall symbol: -P 3*	θ = 3.4–27.5°
a = 9.5145 (4) Å	µ = 6.92 mm−1
α = 114.678 (2)°	T = 183 K
V = 495.88 (6) Å3	Needles, green
Z = 6	0.05 × 0.03 × 0.03 mm
F(000) = 462

Data collection

Bruker–Nonius KappaCCD diffractometer	654 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.045
graphite	θmax = 27.5°, θmin = 3.4°
φ and ω scans	h = −11→12
3338 measured reflections	k = −12→12
755 independent reflections	l = −12→12

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.026	All H-atom parameters refined
wR(F2) = 0.066	w = 1/[σ2(Fo2) + (0.0403P)2 + 0.166P] where P = (Fo2 + 2Fc2)/3
S = 1.02	(Δ/σ)max < 0.001
755 reflections	Δρmax = 0.62 e Å−3
60 parameters	Δρmin = −0.66 e Å−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.014 (2)

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
Cu1	0.91592 (6)	0.43161 (6)	0.19005 (6)	0.00678 (18)
P1	1.31526 (12)	0.74973 (12)	0.68353 (13)	0.0059 (2)
O1	1.1314 (4)	0.5149 (4)	0.4494 (3)	0.0083 (5)
O2	1.5471 (4)	0.8561 (4)	0.7726 (4)	0.0106 (5)
O3	1.3326 (3)	0.7437 (3)	0.8490 (3)	0.0077 (5)
O4	1.2753 (4)	0.8882 (3)	0.6838 (3)	0.0087 (5)
H2	1.555 (8)	0.866 (8)	0.689 (8)	0.040 (14)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cu1	0.0063 (2)	0.0080 (3)	0.0069 (2)	0.0048 (2)	0.0048 (2)	0.0059 (2)
P1	0.0063 (4)	0.0066 (4)	0.0068 (4)	0.0049 (3)	0.0050 (3)	0.0054 (3)
O1	0.0084 (11)	0.0069 (11)	0.0079 (11)	0.0053 (10)	0.0055 (10)	0.0050 (10)
O2	0.0096 (11)	0.0151 (12)	0.0120 (11)	0.0095 (10)	0.0086 (10)	0.0106 (10)
O3	0.0079 (10)	0.0090 (11)	0.0074 (10)	0.0056 (9)	0.0060 (9)	0.0063 (9)
O4	0.0109 (11)	0.0085 (10)	0.0070 (10)	0.0076 (9)	0.0059 (9)	0.0058 (9)

Geometric parameters (Å, °)

Cu1—O1	1.925 (2)	P1—O3	1.541 (2)
Cu1—O4i	1.932 (2)	P1—O2	1.571 (2)
Cu1—O3ii	1.971 (2)	O2—H2	0.87 (5)
Cu1—O3iii	1.992 (2)	O3—Cu1v	1.971 (2)
Cu1—O4iv	2.360 (2)	O3—Cu1iii	1.992 (2)
P1—O4	1.515 (2)	O4—Cu1vi	1.932 (2)
P1—O1	1.530 (2)	O4—Cu1vii	2.360 (2)
O1—Cu1—O4i	163.91 (9)	O1—P1—O3	110.78 (12)
O1—Cu1—O3ii	91.59 (9)	O4—P1—O2	111.98 (13)
O4i—Cu1—O3ii	94.28 (9)	O1—P1—O2	109.68 (13)
O1—Cu1—O3iii	94.20 (9)	O3—P1—O2	102.64 (12)
O4i—Cu1—O3iii	84.72 (9)	P1—O1—Cu1	123.24 (13)
O3ii—Cu1—O3iii	162.12 (8)	P1—O2—H2	110 (3)
O1—Cu1—O4iv	112.90 (9)	P1—O3—Cu1v	128.15 (13)
O4i—Cu1—O4iv	83.13 (4)	P1—O3—Cu1iii	126.96 (13)
O3ii—Cu1—O4iv	74.64 (8)	Cu1v—O3—Cu1iii	101.63 (10)
O3iii—Cu1—O4iv	87.53 (8)	P1—O4—Cu1vi	132.92 (13)
O4—P1—O1	110.21 (12)	P1—O4—Cu1vii	125.51 (12)
O4—P1—O3	111.35 (12)	Cu1vi—O4—Cu1vii	90.84 (8)

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

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1ii	0.87 (5)	1.93 (5)	2.800 (3)	176 (5)

Symmetry codes: (ii) −z+2, −x+2, −y+1.