Barium vanadium(III) hydrogen ­phosphate, Ba₃V₂(HPO₄)₆

Hydro­thermally prepared Ba₃V₂(HPO₄)₆ contains a three-dimensional network of V^IIIO₆ octahedra [d_av(V-O) = 2.014 (2) Å] and HPO₄ [d_av(P-O) = 1.537 (3) Å] tetrahedra, sharing vertices. 12-coordinate Ba²⁺ cations [d_av(Ba-O) = 2.944 (4) Å] complete the structure.

S1. Comment

Barium vanadium phosphates (BaVPOs) show considerable structural variety with at least 15 well characterized BaVPO phases reported so far (Bircsak & Harrison, 1998). Here we report the hydrothermal synthesis of a new barium vanadium(III) hydrogen phosphate, Ba₃V₂(HPO₄)₆ (Figs. 1 and 2), which is built up from barium cations and a vertex-sharing network of VO₆ octahedra and tetrahedral HPO₄ units, fused together via V—O—P bonds.

The barium cation (site symmetry. 2) adopts 12-fold coordination, assuming a cut-off of 3.2 Å for the maximum Ba—O distance [d_av(Ba—O) = 2.944 (4) Å]. The bond valence sum (BVS), calculated by the Brown formalism (1997), of 2.14 for Ba (expected value = 2.00) shows that its valence requirement is satisfied by this coordination.

The two distinct vanadium(III) cations in Ba₃V₂(HPO₄)₆ adopt typical, essentially regular octahedral geometries (Dvoncova et al., 1993), although the point symmetries of V1 (3) and V2 (32) are distinct. BVS values of 2.78 for V1 and 3.00 for V2 are unexceptional (expected: 3.00). The phosphorus atom shows its normal tetrahedral coordination [d_av(P—O) = 1.537 (3) Å, BVS(P1) = 4.97, expected 5.00] and participates in P1—O1—V1, P1—O2—V2, and two terminal P—O bonds. The P1—O3 bond is assumed to be protonated, based on its length, whilst the P1—O4 bond is short, indicating some degree of multiple bond character. Based on geometrical placement of the H atom [d(O3—H) = 0.95 Å], an O3—H···O4 [d(H···O) = 1.62 Å, d(O···O) = 2.575 (6) Å] hydrogen bond is present.

The polyhedral connectivity in Ba₃V₂(HPO₄)₆ results in a three-dimensional network of VO₆ and HPO₄ polyhedra. The smallest identifiable polyhedral loop is a four ring (two VO₆ and two HPO₄ groups) with the proposed O—H···O hydrogen bond occurring across this loop. Every V1O₆ octahedron bonds to six different V2O₆ octahedra via six V1—O1—P1—O2—V2 links. The [V₂(HPO₄)₆]^6- framework encloses channels propagating along [100], [010], and [110], which are occupied by the barium cations.

Like the other vanadium(III)-containing BaVPOs (Bircsak & Harrison, 1998) this phase is three-dimensional in its V/P/O connectivity, and the VO₆ moieties are close to being regular octahedra. Vanadium(IV) and vanadium(V)-containing BaVPOs have quite different, distorted vanadium coordinations (Wadewitz & Müller-Buschbaum, 1996; Kang et al., 1992) and tend to form structures with lower dimensionality. The A₃B₂(XO₄)₆ stoichiometry of Ba₃V₂(HPO₄)₆ appears to be a novel one for phosphates and no similar stoichiometries could be found in the Inorganic Crystal Structure Database (1999).

S2. Experimental

Small, lime green crystals of Ba₃V₂(HPO₄)₆ were prepared from a mixture of BaCO₃ (1.365 g, 6.92 mmol), VCl₃ (1.106 g, 7.03 mmol), H₃PO₄ (3.562 g of an 85% soln, 42.76 mmol), guanidinium carbonate (1.245 g, 6.91 mmol), and water (10.0 ml, 555 mmol), corresponding to a 1:1:6 Ba:V:P starting ratio. These components were heated to 453 K in a sealed teflon-lined hydrothermal bomb for 24 h and the solid products were recovered by vacuum filtration. Reactions omitting guanidine carbonate or starting from the stoichiometric 3:2:6 Ba:V:P atomic ratio led to other, as yet unidentified phases.

S3. Refinement

The highest difference peak is 0.85 Å from Ba1; the deepest difference hole is 0.82 Å from Ba1. The H atoms were assumed to be rifing on O3.

Computing details

Data collection: SMART (Bruker, 1997b); cell refinement: SMART; data reduction: SMART; program(s) used to refine structure: CRYSTALS (Watkin et al., 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: CRYSTALS.

Figures

	Fig. 1. Fragment of the Ba3V2(HPO4)6 structure showing the V/O/P connectivity (50% displacement ellipsoids). Symmetry codes: (a) x-y, x, -z; (b) -y, x-y, z; (c) -x,-y,-z; (d) y-x,-x, z; (e) y, y-x, -z; (f) -1/3 + y, 1/3 + x, -1/6 - z; (g) y-x, 1 - x, z; (h) 2/3 + x-y, 4/3 - y, -1/6 - z; (i) 1 - y, 1 + x-y, z; (j) 2/3 - x, 1/3 - x + y, -1/6 - z.
	Fig. 2. View down [110] of the Ba3V2(HPO4)6 structure in polyhedral representation (VO6 octahedra, PO4 tetrahedra, Ba spheres).

(I)

Crystal data

Ba3V2(HPO4)6	Melting point: decomposes before melting K
Mr = 1089.75	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 3121 reflections
a = 9.423 (1) Å	θ = 4–25°
c = 36.945 (8) Å	µ = 7.69 mm^−1
V = 2840.8 Å^3	T = 298 K
Z = 6	Block, yellow-green
F(000) = 3008.66	0.04 × 0.04 × 0.04 mm
Dx = 3.82 Mg m^−3

Data collection

Bruker SMART area detector diffractometer	753 reflections with I > 1.00σ(I)
Peak integration from area detector frames with the program SAINT (Bruker, 1997) scans	Rint = 0.064
Absorption correction: multi-scan (SADABS; Bruker, 1997a)	θmax = 29.0°, θmin = 2.0°
Tmin = 0.52, Tmax = 0.70	h = −10→10
11318 measured reflections	k = −12→12
830 independent reflections	l = −48→48

Refinement

Refinement on F	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.047	Only H-atom displacement parameters refined
wR(F^2) = 0.049	Chebychev polynomial (Carruthers & Watkin, 1979) with 3 parameters 0.560 0.493 0.317
S = 1.06	(Δ/σ)max = 0.0002
753 reflections	Δρmax = 1.71 e Å^−3
57 parameters	Δρmin = −1.20 e Å^−3
Primary atom site location: structure-invariant direct methods

Special details

Experimental. Crystal decay was monitored by collecting duplicate frames at the end of the experiment, and was found to be negligible.

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

	x	y	z	Uiso*/Ueq
Ba1	0.40831 (4)	0.0000	0.2500	0.0203
V1	0.0000	0.0000	0.0000	0.0136
V2	0.3333	0.6667	−0.0833	0.0137
P1	0.28500 (16)	0.36482 (15)	−0.03241 (4)	0.0178
O1	0.1476 (4)	0.1846 (4)	−0.0340 (1)	0.0206
O2	0.2246 (4)	0.4662 (4)	−0.05233 (9)	0.0184
O3	0.3122 (4)	0.4163 (5)	0.00849 (11)	0.0244
O4	0.4439 (5)	0.3845 (4)	−0.04806 (11)	0.0218
H1	0.4023	0.4898	0.02308	0.0200*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.0156 (2)	0.0245 (3)	0.0238 (3)	0.01224 (13)	0.00040 (7)	0.00081 (14)
V1	0.0095 (5)	0.0095 (5)	0.0220 (9)	0.0047 (2)	0.0000	0.0000
V2	0.0091 (5)	0.0091 (5)	0.0227 (9)	0.0046 (2)	0.0000	0.0000
P1	0.0125 (5)	0.0122 (5)	0.0279 (7)	0.0056 (4)	−0.0027 (5)	0.0021 (4)
O1	0.0154 (15)	0.0131 (15)	0.0314 (19)	0.0057 (13)	−0.0022 (13)	0.0029 (13)
O2	0.0164 (15)	0.0145 (15)	0.0276 (16)	0.0102 (13)	0.0001 (13)	0.0036 (12)
O3	0.0161 (16)	0.0208 (18)	0.031 (2)	0.0052 (14)	−0.0035 (13)	−0.0020 (15)
O4	0.0136 (15)	0.0171 (16)	0.034 (2)	0.0071 (14)	0.0012 (13)	−0.0001 (14)

Geometric parameters (Å, º)

Ba1—O1^i	3.108 (3)	V1—O1^xi	2.030 (4)
Ba1—O1^ii	3.043 (4)	V1—O1^xii	2.030 (4)
Ba1—O1^iii	3.108 (3)	V1—O1^xiii	2.030 (4)
Ba1—O1^iv	3.043 (4)	V2—O2	1.999 (3)
Ba1—O2^i	2.755 (3)	V2—O2^xiv	1.999 (3)
Ba1—O2^iii	2.755 (3)	V2—O2^xv	1.999 (3)
Ba1—O3^v	2.849 (4)	V2—O2^xvi	1.999 (3)
Ba1—O3^vi	2.849 (4)	V2—O2^xvii	1.999 (3)
Ba1—O4^vii	3.030 (4)	V2—O2^xviii	1.999 (3)
Ba1—O4^ii	2.872 (4)	P1—O1	1.537 (4)
Ba1—O4^viii	3.030 (4)	P1—O2	1.524 (3)
Ba1—O4^iv	2.872 (4)	P1—O3	1.569 (4)
V1—O1	2.030 (4)	P1—O4	1.527 (4)
V1—O1^ix	2.030 (4)	O3—H1	0.950
V1—O1^x	2.030 (4)
O1^i—Ba1—O1^ii	53.34 (13)	O3^vi—Ba1—O4^ii	123.30 (11)
O1^i—Ba1—O1^iii	153.92 (13)	O4^vii—Ba1—O4^ii	88.43 (16)
O1^ii—Ba1—O1^iii	151.66 (3)	O2^iii—Ba1—O4^viii	66.7 (1)
O1^i—Ba1—O1^iv	151.66 (3)	O3^v—Ba1—O4^viii	125.32 (11)
O1^ii—Ba1—O1^iv	102.32 (13)	O3^vi—Ba1—O4^viii	51.8 (1)
O1^iii—Ba1—O1^iv	53.34 (13)	O4^vii—Ba1—O4^viii	121.69 (15)
O1^i—Ba1—O2^i	49.38 (9)	O4^ii—Ba1—O4^viii	147.15 (6)
O1^ii—Ba1—O2^i	99.20 (9)	O2^iii—Ba1—O4^iv	128.35 (11)
O1^iii—Ba1—O2^i	105.03 (9)	O3^v—Ba1—O4^iv	123.30 (11)
O1^iv—Ba1—O2^i	158.2 (1)	O3^vi—Ba1—O4^iv	61.26 (11)
O1^i—Ba1—O2^iii	105.03 (9)	O4^vii—Ba1—O4^iv	147.15 (6)
O1^ii—Ba1—O2^iii	158.2 (1)	O4^ii—Ba1—O4^iv	66.98 (16)
O1^iii—Ba1—O2^iii	49.38 (9)	O4^viii—Ba1—O4^iv	88.43 (16)
O1^iv—Ba1—O2^iii	99.20 (9)	O1—V1—O1^ix	180
O2^i—Ba1—O2^iii	59.57 (13)	O1—V1—O1^x	85.72 (16)
O1^i—Ba1—O3^v	66.84 (11)	O1^ix—V1—O1^x	94.28 (16)
O1^ii—Ba1—O3^v	64.1 (1)	O1—V1—O1^xi	94.28 (16)
O1^iii—Ba1—O3^v	112.0 (1)	O1^ix—V1—O1^xi	85.72 (16)
O1^iv—Ba1—O3^v	119.2 (1)	O1^x—V1—O1^xi	180
O2^i—Ba1—O3^v	68.01 (11)	O1—V1—O1^xii	85.72 (16)
O1^i—Ba1—O3^vi	112.0 (1)	O1^ix—V1—O1^xii	94.28 (16)
O1^ii—Ba1—O3^vi	119.2 (1)	O1^x—V1—O1^xii	85.72 (16)
O1^iii—Ba1—O3^vi	66.84 (11)	O1^xi—V1—O1^xii	94.28 (16)
O1^iv—Ba1—O3^vi	64.1 (1)	O1—V1—O1^xiii	94.28 (16)
O2^i—Ba1—O3^vi	107.7 (1)	O1^ix—V1—O1^xiii	85.72 (16)
O1^i—Ba1—O4^vii	103.2 (1)	O1^x—V1—O1^xiii	94.28 (16)
O1^ii—Ba1—O4^vii	115.2 (1)	O1^xi—V1—O1^xiii	85.72 (16)
O1^iii—Ba1—O4^vii	63.3 (1)	O1^xii—V1—O1^xiii	180
O1^iv—Ba1—O4^vii	100.6 (1)	O2—V2—O2^xiv	90.41 (14)
O2^i—Ba1—O4^vii	66.7 (1)	O2—V2—O2^xv	90.41 (14)
O1^i—Ba1—O4^ii	99.6 (1)	O2^xiv—V2—O2^xv	90.41 (14)
O1^ii—Ba1—O4^ii	50.3 (1)	O2—V2—O2^xvi	175.4 (2)
O1^iii—Ba1—O4^ii	102.1 (1)	O2^xiv—V2—O2^xvi	92.9 (2)
O1^iv—Ba1—O4^ii	65.9 (1)	O2^xv—V2—O2^xvi	86.4 (2)
O2^i—Ba1—O4^ii	128.35 (11)	O2—V2—O2^xvii	92.9 (2)
O1^i—Ba1—O4^viii	63.3 (1)	O2^xiv—V2—O2^xvii	86.4 (2)
O1^ii—Ba1—O4^viii	100.6 (1)	O2^xv—V2—O2^xvii	175.4 (2)
O1^iii—Ba1—O4^viii	103.2 (1)	O2^xvi—V2—O2^xvii	90.41 (14)
O1^iv—Ba1—O4^viii	115.2 (1)	O2—V2—O2^xviii	86.4 (2)
O2^i—Ba1—O4^viii	63.22 (11)	O2^xiv—V2—O2^xviii	175.4 (2)
O1^i—Ba1—O4^iv	102.1 (1)	O2^xv—V2—O2^xviii	92.9 (2)
O1^ii—Ba1—O4^iv	65.9 (1)	O2^xvi—V2—O2^xviii	90.41 (14)
O1^iii—Ba1—O4^iv	99.6 (1)	O2^xvii—V2—O2^xviii	90.41 (14)
O1^iv—Ba1—O4^iv	50.3 (1)	O1—P1—O2	107.57 (19)
O2^i—Ba1—O4^iv	145.8 (1)	O1—P1—O3	107.2 (2)
O2^iii—Ba1—O3^v	107.7 (1)	O2—P1—O3	109.0 (2)
O2^iii—Ba1—O3^vi	68.01 (11)	O1—P1—O4	110.6 (2)
O3^v—Ba1—O3^vi	175.32 (15)	O2—P1—O4	113.1 (2)
O2^iii—Ba1—O4^vii	63.22 (11)	O3—P1—O4	109.2 (2)
O3^v—Ba1—O4^vii	51.8 (1)	V1—O1—P1	139.5 (2)
O3^vi—Ba1—O4^vii	125.32 (11)	V2—O2—P1	133.9 (2)
O2^iii—Ba1—O4^ii	145.8 (1)	P1—O3—H1	136.10 (14)
O3^v—Ba1—O4^ii	61.26 (11)

Symmetry codes: (i) −y+2/3, x−y+1/3, z+1/3; (ii) −x+y+2/3, −x+1/3, z+1/3; (iii) −x+1/3, −x+y−1/3, −z+1/6; (iv) y+1/3, x−1/3, −z+1/6; (v) −x+2/3, −y+1/3, −z+1/3; (vi) −x+y+1/3, y−1/3, z+1/6; (vii) x−1/3, y−2/3, z+1/3; (viii) x−y+1/3, −y+2/3, −z+1/6; (ix) −x, −y, −z; (x) −y, x−y, z; (xi) y, −x+y, −z; (xii) −x+y, −x, z; (xiii) x−y, x, −z; (xiv) −y+1, x−y+1, z; (xv) −x+y, −x+1, z; (xvi) x−y+2/3, −y+4/3, −z−1/6; (xvii) −x+2/3, −x+y+1/3, −z−1/6; (xviii) y−1/3, x+1/3, −z−1/6.