K₂Ho(PO₄)(WO₄)

Abstract

A new compound, dipotassium holmium(III) phosphate(V) tungstate(VI), K₂Ho(PO₄)(WO₄), has been obtained during investigation of the K₂O–P₂O₅–WO₃–HoF₃ phase system using the flux technique. The compound is isotypic with K₂Bi(PO₄)(WO₄). Its framework structure consists of flat _∞ ²[HoPO₄] layers parallel to (100) that are made up of _∞ ¹[HoO₈] zigzag chains inter­linked via slightly distorted PO₄ tetra­hedra. WO₄ tetra­hedra are attached above and below these layers, leaving space for the K⁺ counter-cations. The HoO₈, PO₄ and WO₄ units exhibit 2 symmetry.

Related literature

For related structures, see: Ben Amara & Dabbabi (1987 ▶); Marsh (1987 ▶); Zatovsky, Terebilenko, Slobodyanik & Baumer (2006 ▶); Zatovsky, Terebilenko, Slobodyanik, Baumer & Shishkin (2006 ▶).

Experimental

Crystal data

• K₂Ho(PO₄)(WO₄)

• M _r = 585.95

• Orthorhombic,

• a = 6.8820 (10) Å

• b = 12.1485 (18) Å

• c = 19.695 (3) Å

• V = 1646.6 (4) ų

• Z = 8

• Mo Kα radiation

• μ = 24.72 mm⁻¹

• T = 293 (2) K

• 0.10 × 0.09 × 0.07 mm

Data collection

• Oxford Diffraction Xcalibur-3 CCD diffractometer

• Absorption correction: multi-scan based on the method by Blessing (1995 ▶) T _min = 0.102, T _max = 0.177

• 8608 measured reflections

• 1561 independent reflections

• 1257 reflections with I > 2σ(I)

• R _int = 0.055

Refinement

• R[F ² > 2σ(F ²)] = 0.029

• wR(F ²) = 0.071

• S = 1.15

• 1561 reflections

• 62 parameters

• Δρ_max = 1.90 e Å⁻³

• Δρ_min = −1.73 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2005 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2005 ▶); data reduction: CrysAlis RED; 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: WinGX (Farrugia, 1999 ▶).

Supplementary Material

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

Table 1. Selected bond lengths (Å).

W1—O2	1.749 (4)
W1—O1	1.788 (3)
Ho1—O4i	2.274 (3)
Ho1—O1	2.342 (3)
Ho1—O3ii	2.401 (3)
Ho1—O4	2.428 (3)
P1—O3	1.525 (3)
P1—O4	1.552 (3)

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

The co-existence of different anionic units in crystal structures represents an interesting field of investigation. One of the first structural examples of a combination of PO₄ with MoO₄/WO₄ tetrahedra, viz. Na₂Y(MoO₄)(PO₄), was reported to be monoclinic with space group C2/c (Ben Amara & Dabbabi, 1987). Later this structure was reinvestigated and described as orthorhombic, space group Ibca (Marsh, 1987). Recently, the compounds K₂Bi(PO₄)(MO₄) (M=Mo, W) with isotypic structures were obtained by application of the flux method (Zatovsky, Terebilenko, Slobodyanik & Baumer, 2006; Zatovsky, Terebilenko, Slobodyanik, Baumer & Shishkin, 2006). Herein, we report the flux synthesis and crystal structure of a new member of the A₂B(PO₄)(AO₄) (A = Na, K; B = lanthanide, Y, Bi; M = Mo, W) family.

One of the characteristic features of this structure type is the "segregation" of slightly distorted PO₄ and WO₄ tetrahedra into adjacent layers (Fig. 1). The first layer with composition ²_∞[HoPO₄] contains ¹_∞[HoO₈] zigzag chains (Fig. 2). The connection between neighboring chains is achieved via PO₄ tetrahedra. On the top and on the bottom of the ²_∞[HoPO₄] layer, WO₄ tetrahedra are attached. All [HoO₈], PO₄ and WO₄ units exhibit 2 symmetry with bond lengths in the typical ranges (Table 1). The K⁺ cations are situated in the resulting interlayer space and are surrounded by 8 oxygen atoms with K—O bond lengths ranging from 2.683 (4) Å to 3.133 (4) Å.

Experimental

Single crystals of the title compound were grown from a multicomponent high-temperature solution. A mixture of 4.645 g K₂W₂O₇, 0.865 g KPO₃, and 1.150 g K₄P₂O₇ was heated in a platinum crucible up to 1173 K which is above the melting temperature. Then 0.200 g of HoF₃ were added to this melt under stirring. The final mixture was held at this temperature for 1 h and cooled down to room temperature with a rate of 30 Kh^-1. The solidified melt was leached out with warm water to dissolve the superfluous flux. The final product consisted of beige needle-like crystals with a maximum length of up to 5 mm.

Refinement

The highest peak and the deepest hole of the final Fourier map are located 0.58 Å from atom W1 and 1.11 Å from the same atom, respectively.

Figures

Fig. 1.

The layered structure of K2Ho(PO4)(WO4), leaving space where the K+ ions are located.

Fig. 2.

View of K2Ho(PO4)(WO4) with displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) 1,5-x; y; 1-z; (ii) 1-x; 0.5-y; z].

Crystal data

K2Ho(PO4)(WO4)	F(000) = 2064
Mr = 585.95	Dx = 4.727 Mg m−3
Orthorhombic, Ibca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2b 2c	Cell parameters from 8608 reflections
a = 6.882 (1) Å	θ = 3.4–33.0°
b = 12.1485 (18) Å	µ = 24.72 mm−1
c = 19.695 (3) Å	T = 293 K
V = 1646.6 (4) Å3	Prism, pale beige
Z = 8	0.10 × 0.09 × 0.07 mm

Data collection

Oxford Diffraction XCalibur-3 CCD diffractometer	1561 independent reflections
Radiation source: fine-focus sealed tube	1257 reflections with I > 2σ(I)
graphite	Rint = 0.055
φ and ω scans	θmax = 33.0°, θmin = 3.4°
Absorption correction: multi-scan based on the method by Blessing (1995)	h = −10→10
Tmin = 0.102, Tmax = 0.177	k = −18→18
8608 measured reflections	l = −30→29

Refinement

Refinement on F2	0 restraints
Least-squares matrix: full	w = 1/[σ2(Fo2) + (0.0397P)2 + 3.2575P] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.029	(Δ/σ)max < 0.001
wR(F2) = 0.071	Δρmax = 1.90 e Å−3
S = 1.15	Δρmin = −1.73 e Å−3
1561 reflections	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
62 parameters	Extinction coefficient: 0.00010 (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.

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

	x	y	z	Uiso*/Ueq
W1	0.5	0.25	0.334530 (12)	0.01088 (5)
Ho1	0.75	0.325113 (17)	0.5	0.00662 (5)
K1	0.96872 (15)	0.07992 (10)	0.34389 (5)	0.0196 (2)
P1	0.75	0.07042 (10)	0.5	0.0065 (2)
O1	0.7088 (4)	0.2796 (3)	0.38536 (17)	0.0146 (7)
O2	0.4420 (6)	0.3643 (4)	0.2845 (2)	0.0269 (8)
O3	0.7308 (4)	−0.0047 (2)	0.43834 (16)	0.0102 (6)
O4	0.9229 (4)	0.1514 (2)	0.49215 (17)	0.0105 (6)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
W1	0.01432 (9)	0.01167 (9)	0.00666 (9)	−0.00095 (8)	0	0
Ho1	0.00652 (9)	0.00523 (9)	0.00811 (10)	0	−0.00005 (9)	0
K1	0.0204 (4)	0.0248 (5)	0.0137 (4)	−0.0002 (4)	0.0021 (3)	0.0039 (4)
P1	0.0064 (5)	0.0034 (5)	0.0098 (6)	0	0.0000 (5)	0
O1	0.0154 (14)	0.0171 (14)	0.0113 (14)	−0.0035 (11)	−0.0012 (11)	−0.0031 (11)
O2	0.0308 (17)	0.0296 (19)	0.0203 (17)	−0.0008 (17)	0.0013 (15)	0.0126 (16)
O3	0.0126 (13)	0.0079 (11)	0.0101 (13)	−0.0018 (10)	−0.0002 (11)	−0.0010 (9)
O4	0.0052 (10)	0.0066 (11)	0.0198 (16)	−0.0017 (9)	0.0011 (10)	−0.0016 (11)

Geometric parameters (Å, °)

W1—O2i	1.749 (4)	Ho1—K1vii	3.8119 (11)
W1—O2	1.749 (4)	Ho1—K1vi	3.8119 (12)
W1—O1	1.788 (3)	K1—O3	2.683 (3)
W1—O1i	1.788 (3)	K1—O2v	2.689 (4)
W1—K1	3.8352 (12)	K1—O3x	2.747 (3)
W1—K1i	3.8352 (12)	K1—O1vi	2.916 (3)
W1—K1ii	4.0181 (13)	K1—O2xi	2.934 (5)
W1—K1iii	4.0181 (13)	K1—O4	3.063 (3)
W1—K1iv	4.0821 (12)	K1—O1	3.122 (4)
W1—K1v	4.0821 (12)	K1—O2i	3.133 (4)
Ho1—O4vi	2.274 (3)	K1—P1	3.4251 (11)
Ho1—O4vii	2.274 (3)	K1—Ho1vi	3.8119 (11)
Ho1—O1	2.342 (3)	K1—K1iii	3.9511 (13)
Ho1—O1viii	2.342 (3)	P1—O3	1.525 (3)
Ho1—O3ix	2.401 (3)	P1—O3viii	1.525 (3)
Ho1—O3ii	2.401 (3)	P1—O4	1.552 (3)
Ho1—O4viii	2.428 (3)	P1—O4viii	1.552 (3)
Ho1—O4	2.428 (3)	P1—Ho1xii	2.9802 (13)
Ho1—P1ix	2.9802 (13)	P1—K1viii	3.4251 (11)
Ho1—P1	3.0941 (13)
O2i—W1—O2	111.4 (3)	O3x—K1—O4	61.07 (8)
O2i—W1—O1	106.94 (17)	O1vi—K1—O4	69.23 (9)
O2—W1—O1	109.83 (19)	O2xi—K1—O4	130.90 (10)
O2i—W1—O1i	109.83 (19)	O3—K1—O1	76.52 (9)
O2—W1—O1i	106.94 (17)	O2v—K1—O1	100.44 (12)
O1—W1—O1i	111.9 (2)	O3x—K1—O1	117.21 (9)
O4vi—Ho1—O4vii	165.59 (15)	O1vi—K1—O1	84.72 (10)
O4vi—Ho1—O1	94.81 (11)	O2xi—K1—O1	156.62 (10)
O4vii—Ho1—O1	88.59 (11)	O4—K1—O1	58.09 (8)
O4vi—Ho1—O1viii	88.59 (11)	O3—K1—O2i	77.94 (10)
O4vii—Ho1—O1viii	94.81 (11)	O2v—K1—O2i	78.50 (9)
O1—Ho1—O1viii	152.68 (18)	O3x—K1—O2i	156.48 (11)
O4vi—Ho1—O3ix	88.91 (10)	O1vi—K1—O2i	131.64 (12)
O4vii—Ho1—O3ix	78.65 (10)	O2xi—K1—O2i	103.49 (13)
O1—Ho1—O3ix	133.18 (11)	O4—K1—O2i	101.64 (9)
O1viii—Ho1—O3ix	73.88 (12)	O1—K1—O2i	54.04 (10)
O4vi—Ho1—O3ii	78.65 (10)	O3—P1—O3viii	106.4 (2)
O4vii—Ho1—O3ii	88.91 (10)	O3—P1—O4	111.52 (16)
O1—Ho1—O3ii	73.88 (12)	O3viii—P1—O4	113.10 (16)
O1viii—Ho1—O3ii	133.18 (12)	O3—P1—O4viii	113.10 (16)
O3ix—Ho1—O3ii	61.17 (15)	O3viii—P1—O4viii	111.52 (16)
O4vi—Ho1—O4viii	126.77 (7)	O4—P1—O4viii	101.3 (2)
O4vii—Ho1—O4viii	67.63 (12)	W1—O1—Ho1	133.20 (16)
O1—Ho1—O4viii	78.27 (12)	W1—O1—K1vi	124.93 (16)
O1viii—Ho1—O4viii	78.03 (12)	Ho1—O1—K1vi	92.27 (11)
O3ix—Ho1—O4viii	133.56 (10)	W1—O1—K1	99.08 (14)
O3ii—Ho1—O4viii	143.86 (10)	Ho1—O1—K1	111.49 (12)
O4vi—Ho1—O4	67.63 (12)	K1vi—O1—K1	86.88 (9)
O4vii—Ho1—O4	126.77 (8)	W1—O2—K1v	132.6 (2)
O1—Ho1—O4	78.03 (12)	W1—O2—K1ii	115.89 (19)
O1viii—Ho1—O4	78.27 (12)	K1v—O2—K1ii	95.86 (13)
O3ix—Ho1—O4	143.86 (10)	W1—O2—K1i	99.64 (16)
O3ii—Ho1—O4	133.56 (10)	K1v—O2—K1i	120.18 (15)
O4viii—Ho1—O4	59.26 (13)	K1ii—O2—K1i	81.21 (11)
O3—K1—O2v	152.62 (12)	P1—O3—Ho1xii	96.20 (15)
O3—K1—O3x	78.69 (8)	P1—O3—K1	105.64 (14)
O2v—K1—O3x	124.78 (11)	Ho1xii—O3—K1	130.32 (12)
O3—K1—O1vi	119.65 (10)	P1—O3—K1iii	142.66 (16)
O2v—K1—O1vi	86.67 (12)	Ho1xii—O3—K1iii	95.30 (9)
O3x—K1—O1vi	60.35 (9)	K1—O3—K1iii	93.37 (11)
O3—K1—O2xi	93.55 (11)	P1—O4—Ho1vi	146.28 (18)
O2v—K1—O2xi	78.59 (14)	P1—O4—Ho1	99.72 (13)
O3x—K1—O2xi	80.53 (10)	Ho1vi—O4—Ho1	111.83 (11)
O1vi—K1—O2xi	118.34 (11)	P1—O4—K1	89.66 (13)
O3—K1—O4	52.05 (8)	Ho1vi—O4—K1	89.92 (10)
O2v—K1—O4	148.06 (12)	Ho1—O4—K1	110.96 (11)

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