Rubidium zinc phosphate, RbZn₂(PO₄)(HPO₄)

Synthetic RbZn₂(PO₄)(HPO₄) contains anionic layers of vertex-sharing ZnO₄ and (H)PO₄ tetrahedra [d_av(Zn-O) = 1.947 (4) Å and d_av(P-O) = 1.538 (4) Å]. The seven-coordinate Rb⁺ cations [d_av(Rb-O) = 2.987 (4) Å] provide inter-layer charge compensation. RbZn₂(PO₄)(HPO₄) is isostructural with its potassium and ammonium congeners.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• R factor = 0.054
• wR factor = 0.063
• Data-to-parameter ratio = 17.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



FORMU_01  There is a discrepancy between the atom counts in the
          _chemical_formula_sum and _chemical_formula_moiety. This is
          usually due to the moiety formula being in the wrong format.
          Atom count from _chemical_formula_sum:   H1 O8 P2 Rb1 Zn2
          Atom count from _chemical_formula_moiety:

ABSTM_02  When printed, the submitted absorption T values will be replaced
          by the scaled T values. Since the ratio of scaled T's is
          identical to the ratio of reported T values, the scaling does
          not imply a change to the absorption corrections used in the
          study.
          Ratio of Tmax expected/reported      0.832
          Tmax scaled      0.621 Tmin scaled      0.265

---

S1. Comment

The title compound (Fig. 1 and 2) is isostructural with KZn₂(PO₄)(HPO₄) (Averbuch-Pouchot, 1979) and NH₄Zn₂(PO₄)(HPO₄) (Bircsak & Harrison, 1998). The geometrical parameters for the ZnO₄ and (H)PO₄ moieties in this phase are normal. These units assemble into corrugated anionic layers normal to [001]. Bicoordinate Zn—O—P and tricoordinate Zn—O—(Zn,P) O atoms occur in these layers (Bircsak & Harrison, 1998). The [Zn₂(PO₄(HPO₄)]^- sheets are connected by seven-coordinate inter-layer Rb⁺ species and O7—H1···O8 hydrogen bonds.

S2. Experimental

The reaction was carried out in a polypropylene bottle: 1.365 g of Zn(NO₃)₂ was dissolved in 10 ml 1M H₃PO₄ solution resulting in a clear solution. Then, 4.217 g of 50% RbOH solution was added, resulting in a white gel. The bottle was capped, shaken well, and placed in a 343 K oven for 24 h. The crystalline product was recovered by vacuum filtration and washing with acetone.

S3. Refinement

The highest difference peak is 0.86 Å fron Zn2 and the deepest difference hole is 0.82 Å fron Zn1.

Computing details

Data collection: SMART (Bruker, 1999); 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 RbZn2(PO4)(HPO4) (50% displacement ellipsoids, symmetry codes as in Table 1).
	Fig. 2. Polyhedral plot of RbZn2(PO4)(HPO4) viewed down [100]. Colour codes: ZnO4 groups maroon, PO4 groups light blue, Rb atoms dark blue, H atoms red, O—H bonds white and H···O interactions yellow.

(I)

Crystal data

RbZn2(PO4)(HPO4)	F(000) = 383.37
Mr = 407.17	Dx = 3.236 Mg m^−3
Triclinic, P1	Melting point: decomposes before melting K
a = 5.2605 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.9046 (6) Å	Cell parameters from 2016 reflections
c = 9.7244 (7) Å	θ = 2.2–30.0°
α = 75.685 (1)°	µ = 11.92 mm^−1
β = 77.487 (2)°	T = 298 K
γ = 73.489 (1)°	Rod, colourless
V = 417.89 (6) Å^3	0.30 × 0.05 × 0.04 mm
Z = 2

Data collection

Bruker SMART1000 CCD area-detector diffractometer	2385 independent reflections
Radiation source: fine-focus sealed tube	2084 reflections with I > σ(I)
Graphite monochromator	Rint = 0.033
ω scans	θmax = 30.0°, θmin = 0.0°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −5→7
Tmin = 0.318, Tmax = 0.746	k = −12→12
3620 measured reflections	l = −13→12

Refinement

Refinement on F	Hydrogen site location: difference Fourier map
Least-squares matrix: full	Only H-atom displacement parameters refined
R[F^2 > 2σ(F^2)] = 0.054	Chebychev polynomial with 3 parameters (Carruthers & Watkin, 1979) 1.08 0.848 0.686
wR(F^2) = 0.063	(Δ/σ)max = 0.000430
S = 1.07	Δρmax = 1.18 e Å^−3
2084 reflections	Δρmin = −1.86 e Å^−3
120 parameters	Extinction correction: Larson (1967)
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 8.6 (31)
Secondary atom site location: difference Fourier map

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

	x	y	z	Uiso*/Ueq
Rb1	0.28901 (11)	0.29634 (7)	1.17661 (6)	0.0221
Zn1	0.38913 (11)	0.38493 (6)	0.72838 (6)	0.0129
Zn2	0.19652 (11)	0.11187 (6)	0.61011 (6)	0.0129
P1	0.3293 (2)	0.75607 (14)	0.54989 (13)	0.0108
P2	0.8943 (2)	0.24745 (14)	0.88825 (13)	0.0124
O1	0.5941 (8)	0.3010 (5)	0.8851 (4)	0.0226
O2	0.4221 (8)	0.5971 (4)	0.6508 (4)	0.0202
O3	0.4697 (7)	0.2368 (4)	0.5960 (4)	0.0162
O4	0.0240 (8)	0.3875 (4)	0.8266 (5)	0.0227
O5	0.0478 (8)	0.7773 (5)	0.5228 (4)	0.0228
O6	0.3558 (8)	0.8895 (4)	0.6156 (4)	0.0201
O7	0.9306 (9)	0.1922 (5)	1.0520 (4)	0.0204
O8	1.0324 (9)	0.1039 (5)	0.8154 (4)	0.0231
H1	0.9362	0.0836	1.0847	0.006 (13)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Rb1	0.0213 (3)	0.0249 (3)	0.0204 (3)	−0.00254 (19)	−0.00519 (18)	−0.00682 (19)
Zn1	0.0143 (3)	0.0095 (3)	0.0145 (3)	−0.00293 (19)	−0.00087 (19)	−0.00288 (19)
Zn2	0.0146 (3)	0.0099 (3)	0.0145 (3)	−0.00271 (19)	−0.0024 (2)	−0.00348 (19)
P1	0.0105 (5)	0.0093 (5)	0.0122 (5)	−0.0012 (4)	−0.0020 (4)	−0.0024 (4)
P2	0.0122 (5)	0.0116 (5)	0.0126 (5)	−0.0019 (4)	−0.0013 (4)	−0.0026 (4)
O1	0.0118 (16)	0.032 (2)	0.0200 (17)	−0.0030 (14)	−0.0024 (13)	−0.0016 (15)
O2	0.0265 (19)	0.0115 (15)	0.0232 (18)	−0.0053 (14)	−0.0108 (15)	0.0019 (13)
O3	0.0172 (15)	0.0197 (17)	0.0146 (15)	−0.0063 (13)	0.0008 (12)	−0.0098 (13)
O4	0.0169 (17)	0.0097 (15)	0.036 (2)	−0.0045 (13)	0.0066 (15)	−0.0027 (15)
O5	0.0137 (16)	0.030 (2)	0.0217 (18)	−0.0059 (14)	−0.0051 (14)	0.0022 (15)
O6	0.0281 (19)	0.0112 (15)	0.0204 (17)	0.0008 (14)	−0.0048 (15)	−0.0076 (13)
O7	0.031 (2)	0.0135 (16)	0.0168 (16)	−0.0030 (14)	−0.0091 (15)	−0.0017 (13)
O8	0.032 (2)	0.0181 (17)	0.0153 (16)	−0.0031 (16)	0.0044 (15)	−0.0072 (14)

Geometric parameters (Å, º)

Rb1—O1	2.936 (4)	Zn2—O5^iv	1.914 (4)
Rb1—O2^i	2.956 (4)	Zn2—O6^v	1.911 (4)
Rb1—O4^ii	2.825 (4)	Zn2—O8^iii	1.989 (4)
Rb1—O5^ii	3.096 (4)	P1—O2	1.527 (4)
Rb1—O6^i	2.922 (4)	P1—O3^vi	1.574 (4)
Rb1—O7^iii	2.902 (4)	P1—O5	1.511 (4)
Rb1—O7	3.275 (4)	P1—O6	1.532 (4)
Zn1—O1	1.933 (4)	P2—O1	1.519 (4)
Zn1—O2	1.896 (4)	P2—O4^vii	1.522 (4)
Zn1—O3	1.965 (3)	P2—O7	1.583 (4)
Zn1—O4	1.948 (4)	P2—O8	1.536 (4)
Zn2—O3	2.017 (4)	O7—H1	0.935
O1—Rb1—O2^i	109.01 (12)	O3—Zn2—O6^v	112.53 (17)
O1—Rb1—O4^ii	104.99 (12)	O5^iv—Zn2—O6^v	118.50 (19)
O2^i—Rb1—O4^ii	80.07 (12)	O3—Zn2—O8^iii	99.99 (16)
O1—Rb1—O5^ii	167.76 (12)	O5^iv—Zn2—O8^iii	114.21 (18)
O2^i—Rb1—O5^ii	80.17 (11)	O6^v—Zn2—O8^iii	99.61 (16)
O4^ii—Rb1—O5^ii	84.24 (12)	O2—P1—O3^vi	109.3 (2)
O1—Rb1—O6^i	109.01 (11)	O2—P1—O5	111.1 (2)
O2^i—Rb1—O6^i	49.7 (1)	O3^vi—P1—O5	110.3 (2)
O4^ii—Rb1—O6^i	125.92 (12)	O2—P1—O6	107.8 (2)
O5^ii—Rb1—O6^i	70.30 (11)	O3^vi—P1—O6	105.1 (2)
O1—Rb1—O7^iii	81.22 (12)	O5—P1—O6	112.9 (2)
O2^i—Rb1—O7^iii	169.71 (12)	O1—P2—O4^vii	110.5 (2)
O4^ii—Rb1—O7^iii	96.55 (12)	O1—P2—O7	106.7 (2)
O5^ii—Rb1—O7^iii	89.86 (11)	O4^vii—P2—O7	106.7 (2)
O6^i—Rb1—O7^iii	128.91 (11)	O1—P2—O8	112.7 (3)
O1—Rb1—O7	46.9 (1)	O4^vii—P2—O8	112.4 (2)
O2^i—Rb1—O7	72.67 (11)	O7—P2—O8	107.4 (2)
O4^ii—Rb1—O7	125.87 (11)	Zn1—O1—P2	132.1 (3)
O5^ii—Rb1—O7	133.3 (1)	Zn1—O2—P1	148.1 (3)
O6^i—Rb1—O7	63.1 (1)	Zn1—O3—Zn2	117.15 (18)
O7^iii—Rb1—O7	116.65 (13)	Zn1—O3—P1^vi	126.0 (2)
O1—Zn1—O2	107.49 (18)	Zn2—O3—P1^vi	113.76 (19)
O1—Zn1—O3	112.16 (17)	Zn1—O4—P2^iii	128.6 (2)
O2—Zn1—O3	118.15 (17)	Zn2^iv—O5—P1	143.0 (3)
O1—Zn1—O4	102.21 (18)	Zn2^viii—O6—P1	138.1 (3)
O2—Zn1—O4	109.78 (16)	P2—O7—H1	111.21 (15)
O3—Zn1—O4	105.86 (17)	Zn2^vii—O8—P2	126.7 (2)
O3—Zn2—O5^iv	110.13 (17)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O7—H1···O8^ix	0.93	1.69	2.605 (6)	164

Symmetry code: (ix) −x+2, −y, −z+2.