Barium tetraphosphate

The structure of the low-temperature form of barium tetraphosphate, Ba₃P₄O₁₃, shows the tetraphosphate to exist in an S conformation.

S1. Comment

In 1986, Millet et al. (1986) reported unit-cell dimensions for low- and high-temperature forms of Ba₃P₄O₁₃. The low-temperature form (triclinic space group P1 or P1; a = 5.757, b = 7.243, c = 8.104 Å, α = 82.75, β = 73.94, γ = 70.71°) transforms at 1143 K into the high-temperature form (orthorhombic space group Pbcm; a = 7.107, b = 13.883, c = 19.219 Å) (cell dimensions from precession camera data).

Gatehouse et al. (1991) later reported a crystal structure of the low-temperature form in the triclinic space group P1 [a = 5.691 (5), b = 7.238 (7), c = 8.006 (5) Å, α = 83.65 (5), β = 75.95 (8), γ = 70.49 (7)°]. The asymmetric unit consisted of two Ba atoms and a linear tetraphosphate group chain (P₄O₁₃), with one Ba atom and the central O atom of the P₄O₁₃ chain existing on a center of symmetry. Disorder of the central bridging O atom and of the two terminal O atoms on adjacent P atoms led to an incomplete refinement. Only Ba atoms were refined anisotropically, while P and O atoms were refined with isotropic displacement parameters.

We have isolated crystals of the low-temperature form of Ba₃P₄O₁₃ and refined single-crystal data in a triclinic cell of doubled volume [600.65 (12) Å]. We find the disorder evident in the P₄O₁₃ group seen in the triclinic cell of volume 301 Å to be completely absent in our refinement. Moreover, the central bridging O atom shows a normal angle P—O—P of 151.4 (4) Å.

The P₄O₁₃ group has an S conformation (Fig. 1) as is common (Averbuch-Pouchot, 1987; Averbuch-Pouchot & Durif, 1987) and not a U conformation (Lii et al., 1989). The P···P···P···P torsion angle is 179.1°, consistent with this assignment. The four P atoms are coplanar (s.u. 0.012). Relative O-atom conformations are pseudo-eclipsed about the P1···P2 direction, pseudo-staggered about about the P2···P3 direction and pseudo-eclipsed about the P3···P4 line. Average O—P···P—O torsion angles about the three P—P directions are 9.8, 56.1 and 30.63°, respectively, further evidence of the need to refine the O atoms of the P₄O₁₃ group without constrained symmetry. Angles at the brigding O atoms are 128.6 (3), 151.4 (4) and 130.0 (3)°. [Can an s.u. value be provided for the P···P···P···P torsion angle; is the s.u. = 0.012 value an r.m.s. deviation ?]

The four Ba atoms appear related by the pseudosymmetry element (1/2 + x, y, 1/2 + z). Atoms Ba1 and Ba2 exist on a center of symmetry and are eight-coordinate, with Ba—O distances in the range 2.659 (4)–3.113 (5) Å for Ba1 and 2.719 (4)–2.938 (4) Å for Ba2. Atom Ba3 is seven-coordinate [Ba—O 2.662 (4)–2.891 (4) Å], while Ba4 has eight O-atom neighbors within the range 2.680 (4)–3.194 (4) Å.

Ba atoms are seen in two tunnels extending in the [100] direction. These tunnels differ in their placement in the curves of the P₄O₁₃ groups (Ba3 and Ba4) or at the ends of such groups (Ba1 and Ba2) (Fig. 2).

S2. Experimental

Crystals of Ba₃P₄O₁₃ were obtained from a mixture of Na₂CO₃, BaCO₃ and (NH₄)₂HPO₄ (proportion 2:1:2) which was ground together in an agate morter and then heated in a porcelain crucible from 373 K to 873 K. A quantity of (NH₄)₂HPO₄ equal to 10% of the final mass was added to the top of the crucible and the material then heated to fusion (1173 K). Colorless crystals were found in the product after controlled cooling (6° h) to 673 K.

Computing details

Data collection: XSCANS (Siemens, 1991); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1990); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of the P4O13 group of the title compound. Displacement ellipsoids are shown at the 50% probability level.
	Fig. 2. Projection of Ba3P4O13 on to the 011 plane.

Barium tetraphosphate

Crystal data

Ba3P4O13	Z = 2
Mr = 743.90	F(000) = 664
Triclinic, P1	Dx = 4.113 Mg m^−3
a = 7.557 (1) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.618 (1) Å	Cell parameters from 23 reflections
c = 10.582 (1) Å	θ = 6.2–12.8°
α = 108.26 (1)°	µ = 10.33 mm^−1
β = 104.50 (1)°	T = 293 K
γ = 102.37 (1)°	Plate, colorless
V = 600.65 (12) Å^3	0.15 × 0.15 × 0.15 mm

Data collection

Syntex P4 four-circle diffractometer	2777 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 30.0°, θmin = 2.2°
θ/2θ scans	h = −10→1
Absorption correction: ψ scan (XEMP; Siemens, 1990)	k = −11→11
Tmin = 0.72, Tmax = 0.78	l = −14→14
4118 measured reflections	3 standard reflections every 97 reflections
3397 independent reflections	intensity decay: 0.0%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.032	w = 1/[σ^2(Fo^2) + (0.0592P)^2 + 5.8638P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.099	(Δ/σ)max = 0.001
S = 0.90	Δρmax = 0.03 e Å^−3
3397 reflections	Δρmin = −0.08 e Å^−3
185 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0173 (7)

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
Ba1	0.5000	0.0000	0.0000	0.01144 (13)
Ba2	0.0000	0.0000	−0.5000	0.01131 (13)
Ba3	0.36448 (4)	−0.22221 (4)	0.27035 (3)	0.01034 (12)
Ba4	−0.14908 (4)	−0.22935 (4)	−0.23031 (3)	0.00975 (12)
P1	0.67328 (18)	−0.79731 (16)	0.36439 (13)	0.0085 (2)
O11	0.7021 (7)	−0.8590 (5)	0.4845 (4)	0.0180 (8)
O12	0.8231 (6)	−0.8022 (5)	0.2953 (5)	0.0213 (9)
O13	0.4678 (5)	−0.8853 (5)	0.2589 (4)	0.0130 (7)
O14	0.6931 (6)	−0.5923 (5)	0.4392 (4)	0.0128 (7)
P2	0.66111 (18)	−0.46114 (16)	0.36628 (13)	0.0082 (2)
O22	0.7348 (7)	−0.2855 (5)	0.4820 (4)	0.0206 (9)
O23	0.4588 (6)	−0.5152 (6)	0.2721 (5)	0.0252 (10)
O24	0.8044 (7)	−0.4632 (6)	0.2796 (5)	0.0250 (9)
P3	0.84691 (18)	−0.52350 (16)	0.13519 (14)	0.0084 (2)
O32	1.0572 (6)	−0.4979 (6)	0.1840 (5)	0.0211 (9)
O33	0.7222 (7)	−0.6974 (5)	0.0294 (4)	0.0231 (9)
O34	0.8026 (6)	−0.3915 (5)	0.0675 (4)	0.0125 (7)
P4	0.83901 (17)	−0.18521 (16)	0.14304 (13)	0.0077 (2)
O41	0.8093 (6)	−0.1206 (5)	0.0241 (4)	0.0147 (7)
O42	1.0474 (5)	−0.1049 (5)	0.2437 (4)	0.0123 (7)
O43	0.6970 (5)	−0.1691 (5)	0.2196 (4)	0.0146 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.0107 (2)	0.0116 (2)	0.0124 (2)	0.00328 (16)	0.00484 (16)	0.00450 (16)
Ba2	0.0086 (2)	0.0139 (2)	0.0091 (2)	0.00191 (16)	0.00249 (15)	0.00303 (16)
Ba3	0.00881 (16)	0.01054 (18)	0.01359 (18)	0.00363 (12)	0.00437 (12)	0.00637 (12)
Ba4	0.00899 (17)	0.00994 (17)	0.01224 (18)	0.00368 (12)	0.00422 (12)	0.00586 (12)
P1	0.0079 (5)	0.0091 (6)	0.0088 (6)	0.0033 (4)	0.0023 (4)	0.0040 (4)
O11	0.028 (2)	0.0167 (19)	0.0156 (19)	0.0132 (17)	0.0065 (16)	0.0110 (16)
O12	0.0187 (19)	0.0165 (19)	0.035 (2)	0.0060 (16)	0.0211 (18)	0.0088 (18)
O13	0.0087 (16)	0.0114 (17)	0.0150 (18)	0.0029 (13)	0.0009 (13)	0.0030 (14)
O14	0.0186 (18)	0.0085 (16)	0.0120 (17)	0.0059 (14)	0.0040 (14)	0.0047 (13)
P2	0.0075 (5)	0.0079 (5)	0.0081 (5)	0.0020 (4)	0.0026 (4)	0.0023 (4)
O22	0.033 (2)	0.0086 (17)	0.0151 (19)	0.0015 (16)	0.0077 (17)	0.0020 (14)
O23	0.0105 (17)	0.021 (2)	0.038 (3)	0.0013 (16)	−0.0026 (17)	0.016 (2)
O24	0.036 (2)	0.030 (2)	0.026 (2)	0.020 (2)	0.021 (2)	0.0181 (19)
P3	0.0081 (5)	0.0072 (5)	0.0092 (6)	0.0020 (4)	0.0031 (4)	0.0025 (4)
O32	0.0117 (17)	0.021 (2)	0.033 (2)	0.0053 (15)	0.0051 (16)	0.0150 (18)
O33	0.031 (2)	0.0086 (17)	0.016 (2)	−0.0063 (16)	−0.0016 (17)	0.0020 (15)
O34	0.0154 (17)	0.0080 (16)	0.0111 (17)	0.0023 (14)	0.0022 (14)	0.0027 (13)
P4	0.0071 (5)	0.0089 (5)	0.0078 (6)	0.0029 (4)	0.0022 (4)	0.0041 (4)
O41	0.0204 (19)	0.0156 (18)	0.0125 (18)	0.0099 (15)	0.0062 (15)	0.0080 (15)
O42	0.0074 (15)	0.0126 (17)	0.0142 (18)	0.0045 (13)	0.0008 (13)	0.0033 (14)
O43	0.0121 (16)	0.0126 (17)	0.023 (2)	0.0044 (14)	0.0120 (15)	0.0066 (15)

Geometric parameters (Å, º)

Ba1—O33^i	2.659 (4)	Ba4—O23^ix	2.680 (4)
Ba1—O33^ii	2.659 (4)	Ba4—O41^vi	2.682 (4)
Ba1—O13^ii	2.699 (4)	Ba4—O12^ii	2.700 (4)
Ba1—O13^i	2.699 (4)	Ba4—O32^ii	2.739 (4)
Ba1—O41^iii	2.742 (4)	Ba4—O13^ix	2.777 (4)
Ba1—O41	2.742 (4)	Ba4—O22^iv	2.799 (4)
Ba1—O12^i	3.113 (5)	Ba4—O42^iii	2.876 (4)
Ba1—O12^ii	3.113 (5)	Ba4—O41^iii	3.194 (4)
Ba1—O43^iii	3.325 (4)	Ba4—P4^iii	3.5171 (14)
Ba1—O43	3.325 (4)	Ba4—P3^ii	3.6111 (14)
Ba2—O42^iv	2.719 (4)	Ba4—Ba1^vi	4.3980 (6)
Ba2—O42^iii	2.719 (4)	P1—O12	1.495 (4)
Ba2—O22^iii	2.740 (4)	P1—O11	1.511 (4)
Ba2—O22^iv	2.740 (4)	P1—O13	1.526 (4)
Ba2—O11^v	2.772 (4)	P1—O14	1.649 (4)
Ba2—O11^ii	2.772 (4)	O14—P2	1.582 (4)
Ba2—O43^iii	2.938 (4)	P2—O23	1.479 (4)
Ba2—O43^iv	2.938 (4)	P2—O22	1.495 (4)
Ba3—O32^vi	2.662 (4)	P2—O24	1.584 (4)
Ba3—O11^vii	2.671 (4)	O24—P3	1.590 (4)
Ba3—O43	2.674 (4)	P3—O33	1.484 (4)
Ba3—O23	2.771 (5)	P3—O32	1.486 (4)
Ba3—O42^vi	2.779 (4)	P3—O34	1.572 (4)
Ba3—O13^i	2.890 (4)	O34—P4	1.632 (4)
Ba3—O33^ii	2.891 (4)	P4—O43	1.502 (4)
Ba3—O11^i	3.268 (5)	P4—O41	1.515 (4)
Ba3—Ba2^viii	4.4559 (6)	P4—O42	1.524 (4)
O33^i—Ba1—O33^ii	180.0	O43—Ba3—O23	77.77 (13)
O33^i—Ba1—O13^ii	84.67 (13)	O32^vi—Ba3—O42^vi	73.74 (12)
O33^ii—Ba1—O13^ii	95.33 (13)	O11^vii—Ba3—O42^vi	71.05 (13)
O33^i—Ba1—O13^i	95.33 (13)	O43—Ba3—O42^vi	139.50 (12)
O33^ii—Ba1—O13^i	84.67 (13)	O23—Ba3—O42^vi	139.83 (12)
O13^ii—Ba1—O13^i	180.0	O32^vi—Ba3—O13^i	140.19 (12)
O33^i—Ba1—O41^iii	89.73 (14)	O11^vii—Ba3—O13^i	99.94 (12)
O33^ii—Ba1—O41^iii	90.27 (14)	O43—Ba3—O13^i	71.87 (11)
O13^ii—Ba1—O41^iii	107.47 (12)	O23—Ba3—O13^i	149.41 (12)
O13^i—Ba1—O41^iii	72.53 (12)	O42^vi—Ba3—O13^i	70.37 (12)
O33^i—Ba1—O41	90.27 (14)	O32^vi—Ba3—O33^ii	83.77 (13)
O33^ii—Ba1—O41	89.73 (14)	O11^vii—Ba3—O33^ii	156.34 (14)
O13^ii—Ba1—O41	72.53 (12)	O43—Ba3—O33^ii	71.73 (13)
O13^i—Ba1—O41	107.47 (12)	O23—Ba3—O33^ii	96.90 (14)
O41^iii—Ba1—O41	180.0	O42^vi—Ba3—O33^ii	86.11 (13)
O33^i—Ba1—O12^i	66.39 (12)	O13^i—Ba3—O33^ii	77.25 (11)
O33^ii—Ba1—O12^i	113.61 (12)	O32^vi—Ba3—O11^i	158.46 (13)
O13^ii—Ba1—O12^i	129.19 (11)	O11^vii—Ba3—O11^i	74.53 (14)
O13^i—Ba1—O12^i	50.81 (11)	O43—Ba3—O11^i	64.14 (12)
O41^iii—Ba1—O12^i	112.89 (11)	O23—Ba3—O11^i	114.68 (11)
O41—Ba1—O12^i	67.11 (11)	O42^vi—Ba3—O11^i	99.10 (11)
O33^i—Ba1—O12^ii	113.61 (12)	O13^i—Ba3—O11^i	47.46 (11)
O33^ii—Ba1—O12^ii	66.39 (12)	O33^ii—Ba3—O11^i	116.47 (11)
O13^ii—Ba1—O12^ii	50.81 (11)	O23^ix—Ba4—O41^vi	79.32 (14)
O13^i—Ba1—O12^ii	129.19 (11)	O23^ix—Ba4—O12^ii	137.41 (14)
O41^iii—Ba1—O12^ii	67.11 (11)	O41^vi—Ba4—O12^ii	129.31 (14)
O41—Ba1—O12^ii	112.89 (11)	O23^ix—Ba4—O32^ii	67.08 (13)
O12^i—Ba1—O12^ii	180.0	O41^vi—Ba4—O32^ii	89.92 (13)
O33^i—Ba1—O43^iii	65.02 (12)	O12^ii—Ba4—O32^ii	80.64 (13)
O33^ii—Ba1—O43^iii	114.98 (12)	O23^ix—Ba4—O13^ix	70.87 (13)
O13^ii—Ba1—O43^iii	64.77 (11)	O41^vi—Ba4—O13^ix	72.23 (12)
O13^i—Ba1—O43^iii	115.23 (11)	O12^ii—Ba4—O13^ix	140.98 (13)
O41^iii—Ba1—O43^iii	48.29 (10)	O32^ii—Ba4—O13^ix	136.65 (12)
O41—Ba1—O43^iii	131.71 (10)	O23^ix—Ba4—O22^iv	91.83 (14)
O12^i—Ba1—O43^iii	127.02 (11)	O41^vi—Ba4—O22^iv	151.19 (13)
O12^ii—Ba1—O43^iii	52.98 (11)	O12^ii—Ba4—O22^iv	74.74 (14)
O33^i—Ba1—O43	114.98 (12)	O32^ii—Ba4—O22^iv	111.96 (13)
O33^ii—Ba1—O43	65.02 (12)	O13^ix—Ba4—O22^iv	78.97 (13)
O13^ii—Ba1—O43	115.23 (11)	O23^ix—Ba4—O42^iii	140.74 (12)
O13^i—Ba1—O43	64.77 (11)	O41^vi—Ba4—O42^iii	95.96 (12)
O41^iii—Ba1—O43	131.71 (10)	O12^ii—Ba4—O42^iii	74.60 (12)
O41—Ba1—O43	48.29 (10)	O32^ii—Ba4—O42^iii	152.17 (11)
O12^i—Ba1—O43	52.98 (11)	O13^ix—Ba4—O42^iii	70.61 (12)
O12^ii—Ba1—O43	127.02 (11)	O22^iv—Ba4—O42^iii	73.65 (11)
O43^iii—Ba1—O43	180.0	O23^ix—Ba4—O41^iii	149.88 (13)
O42^iv—Ba2—O42^iii	180.0	O41^vi—Ba4—O41^iii	70.66 (13)
O42^iv—Ba2—O22^iii	77.09 (12)	O12^ii—Ba4—O41^iii	66.32 (12)
O42^iii—Ba2—O22^iii	102.91 (12)	O32^ii—Ba4—O41^iii	109.66 (11)
O42^iv—Ba2—O22^iv	102.91 (12)	O13^ix—Ba4—O41^iii	101.26 (11)
O42^iii—Ba2—O22^iv	77.09 (12)	O22^iv—Ba4—O41^iii	115.71 (11)
O22^iii—Ba2—O22^iv	180.0	O42^iii—Ba4—O41^iii	48.33 (11)
O42^iv—Ba2—O11^v	109.52 (12)	O12—P1—O11	115.0 (3)
O42^iii—Ba2—O11^v	70.48 (12)	O12—P1—O13	113.1 (3)
O22^iii—Ba2—O11^v	94.88 (13)	O11—P1—O13	111.0 (2)
O22^iv—Ba2—O11^v	85.12 (13)	O12—P1—O14	106.3 (2)
O42^iv—Ba2—O11^ii	70.48 (12)	O11—P1—O14	104.6 (2)
O42^iii—Ba2—O11^ii	109.52 (12)	O13—P1—O14	105.9 (2)
O22^iii—Ba2—O11^ii	85.12 (13)	P2—O14—P1	128.6 (3)
O22^iv—Ba2—O11^ii	94.88 (13)	O23—P2—O22	115.9 (3)
O11^v—Ba2—O11^ii	180.0	O23—P2—O14	111.1 (2)
O42^iv—Ba2—O43^iii	127.36 (10)	O22—P2—O14	107.0 (2)
O42^iii—Ba2—O43^iii	52.64 (10)	O23—P2—O24	111.3 (3)
O22^iii—Ba2—O43^iii	68.61 (12)	O22—P2—O24	106.1 (3)
O22^iv—Ba2—O43^iii	111.39 (12)	O14—P2—O24	104.7 (2)
O11^v—Ba2—O43^iii	112.02 (12)	P2—O24—P3	151.4 (4)
O11^ii—Ba2—O43^iii	67.98 (12)	O33—P3—O32	115.9 (3)
O42^iv—Ba2—O43^iv	52.64 (10)	O33—P3—O34	106.6 (2)
O42^iii—Ba2—O43^iv	127.36 (10)	O32—P3—O34	110.8 (2)
O22^iii—Ba2—O43^iv	111.39 (12)	O33—P3—O24	115.5 (3)
O22^iv—Ba2—O43^iv	68.61 (12)	O32—P3—O24	102.8 (3)
O11^v—Ba2—O43^iv	67.98 (12)	O34—P3—O24	104.8 (2)
O11^ii—Ba2—O43^iv	112.02 (12)	P3—O34—P4	130.0 (3)
O43^iii—Ba2—O43^iv	180.0	O43—P4—O41	114.6 (2)
O32^vi—Ba3—O11^vii	83.94 (14)	O43—P4—O42	112.4 (2)
O32^vi—Ba3—O43	133.87 (13)	O41—P4—O42	110.8 (2)
O11^vii—Ba3—O43	130.28 (13)	O43—P4—O34	105.9 (2)
O32^vi—Ba3—O23	66.87 (13)	O41—P4—O34	105.7 (2)
O11^vii—Ba3—O23	96.74 (14)	O42—P4—O34	106.8 (2)

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