Reinvestigation of NH₄[Co(H₂O)₆]PO₄ based on single-crystal data

The structure of the title compound, ammonium hexa­aqua­cobalt(II) orthophosphate, known from powder data, has been refined based on single-crystal data. The compound crystallizes in the struvite [NH₄Mg(H₂O)₆PO₄] structure type and is isotypic with the homologous nickel phase. The framework is built of NH₄⁺, [Co(H₂O)₆]²⁺ and PO₄³⁻ ions stacked in two kinds of ribbons parallel to (010). Co^II atoms are well separated in the framework, with the shortest Co...Co distance being over 6 Å.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](P-O) = 0.003 Å
• R factor = 0.029
• wR factor = 0.066
• Data-to-parameter ratio = 11.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.80 mm
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O4     -   H41    ...       0.70 Ang.
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O4     -   H42    ...       0.71 Ang.
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O5     -   H51    ...       0.71 Ang.
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O5     -   H52    ...       0.71 Ang.
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O7     -   H7     ...       0.71 Ang.
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O7     -   H7_b   ...       0.71 Ang.
PLAT731_ALERT_1_C Bond    Calc     0.71(5), Rep     0.71(2) ......       2.50 su-Rat
              O5   -H52     1.555   1.555
PLAT735_ALERT_1_C D-H     Calc     0.71(5), Rep     0.71(2) ......       2.50 su-Rat
              O5   -H52     1.555   1.555
PLAT736_ALERT_1_C H...A   Calc     2.32(5), Rep     2.32(2) ......       2.50 su-Rat
              H52  -O7      1.555   1.545

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.59
           From the CIF: _reflns_number_total               1136
           Count of symmetry unique reflns          630
           Completeness (_total/calc)            180.32%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       506
           Fraction of Friedel pairs measured     0.803
           Are heavy atom types Z>Si present          yes

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
  10 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   7 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: COLLECT (Nonius, 1998); data reduction: EVALCCD (Nonius, 1998); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999) and ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

ammonium hexaaquacobalt(II) orthophosphate

Crystal data

(NH4)[Co(H2O)6](PO4)	F(000) = 290
Mr = 280.04	Dx = 1.947 Mg m^−3
Orthorhombic, Pmn21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac-2	Cell parameters from 4521 reflections
a = 6.946 (2) Å	θ = 5.5–29.5°
b = 6.157 (2) Å	µ = 2.00 mm^−1
c = 11.172 (6) Å	T = 293 K
V = 477.8 (3) Å^3	Prism, purple
Z = 2	0.80 × 0.25 × 0.25 mm

Data collection

Nonius KappaCCD diffractometer	1136 independent reflections
Radiation source: fine-focus sealed tube	1016 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
φ and ω scans	θmax = 27.6°, θmin = 5.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→9
Tmin = 0.230, Tmax = 0.610	k = −7→8
3846 measured reflections	l = −13→14

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.029	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.066	w = 1/[σ^2(Fo^2) + (0.0285P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
1136 reflections	Δρmax = 0.37 e Å^−3
99 parameters	Δρmin = −0.39 e Å^−3
19 restraints	Absolute structure: Flack (1983), 472 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.07 (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
Co1	0.0000	0.62726 (9)	0.11520 (6)	0.02051 (16)
P1	0.0000	0.00246 (17)	0.48747 (11)	0.0151 (2)
O1	0.1825 (3)	−0.1175 (3)	0.4454 (2)	0.0214 (5)
O2	0.0000	0.2344 (5)	0.4339 (3)	0.0227 (7)
O3	0.0000	0.0192 (4)	0.6248 (3)	0.0223 (6)
O4	0.2223 (4)	0.7377 (5)	0.2254 (2)	0.0265 (5)
O5	0.0000	0.3174 (6)	0.1997 (4)	0.0397 (10)
O6	−0.2096 (4)	0.5206 (4)	−0.0009 (3)	0.0332 (6)
O7	0.0000	0.9352 (7)	0.0283 (4)	0.0411 (11)
N1	0.5000	0.3662 (9)	0.2548 (5)	0.0337 (11)
H7	0.080 (5)	0.987 (6)	0.001 (4)	0.043 (7)*
H41	0.258 (6)	0.803 (6)	0.179 (3)	0.043 (7)*
H42	0.190 (6)	0.768 (7)	0.283 (3)	0.043 (7)*
H51	0.0000	0.279 (10)	0.260 (3)	0.043 (7)*
H52	0.0000	0.228 (7)	0.159 (5)	0.043 (7)*
H61	−0.277 (6)	0.581 (7)	−0.034 (4)	0.043 (7)*
H62	−0.239 (7)	0.416 (7)	−0.011 (5)	0.034 (12)*
H1	0.396 (6)	0.422 (9)	0.241 (6)	0.085 (14)*
H2	0.5000	0.376 (15)	0.328 (3)	0.085 (14)*
H3	0.5000	0.257 (8)	0.214 (7)	0.085 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0221 (3)	0.0185 (3)	0.0209 (3)	0.000	0.000	−0.0007 (3)
P1	0.0163 (5)	0.0127 (4)	0.0162 (5)	0.000	0.000	−0.0007 (4)
O1	0.0196 (10)	0.0189 (10)	0.0257 (12)	0.0055 (10)	−0.0002 (10)	−0.0050 (9)
O2	0.0238 (16)	0.0165 (13)	0.0279 (17)	0.000	0.000	0.0044 (15)
O3	0.0276 (15)	0.0223 (13)	0.0171 (16)	0.000	0.000	−0.0030 (16)
O4	0.0275 (14)	0.0346 (14)	0.0175 (13)	−0.0085 (12)	−0.0005 (11)	−0.0037 (12)
O5	0.078 (3)	0.0188 (18)	0.022 (2)	0.000	0.000	0.0039 (14)
O6	0.0327 (15)	0.0183 (13)	0.0485 (18)	0.0041 (11)	−0.0174 (14)	−0.0107 (13)
O7	0.0211 (18)	0.037 (2)	0.066 (3)	0.000	0.000	0.030 (2)
N1	0.035 (3)	0.030 (2)	0.035 (3)	0.000	0.000	−0.004 (2)

Geometric parameters (Å, º)

Co1—O6	2.057 (3)	O4—H41	0.70 (2)
Co1—O6^i	2.057 (3)	O4—H42	0.71 (2)
Co1—O4	2.089 (2)	O5—H51	0.71 (2)
Co1—O4^i	2.089 (2)	O5—H52	0.71 (2)
Co1—O5	2.129 (4)	O6—H61	0.71 (2)
Co1—O7	2.130 (4)	O6—H62	0.69 (4)
P1—O3	1.538 (4)	O7—H7	0.71 (2)
P1—O1	1.540 (2)	N1—H1	0.81 (3)
P1—O1^i	1.540 (2)	N1—H2	0.82 (3)
P1—O2	1.549 (3)	N1—H3	0.81 (3)
O6—Co1—O6^i	90.07 (18)	O1—P1—O1^i	110.72 (17)
O6—Co1—O4	177.01 (13)	O3—P1—O2	108.91 (17)
O6^i—Co1—O4	87.28 (11)	O1—P1—O2	108.92 (11)
O6—Co1—O4^i	87.28 (11)	O1^i—P1—O2	108.92 (11)
O6^i—Co1—O4^i	177.01 (13)	Co1—O4—H41	91 (4)
O4—Co1—O4^i	95.34 (15)	Co1—O4—H42	113 (4)
O6—Co1—O5	89.61 (12)	H41—O4—H42	130 (5)
O6^i—Co1—O5	89.61 (12)	Co1—O5—H51	136 (6)
O4—Co1—O5	91.74 (11)	Co1—O5—H52	114 (5)
O4^i—Co1—O5	91.74 (11)	H51—O5—H52	110 (7)
O6—Co1—O7	89.81 (14)	Co1—O6—H61	129 (4)
O6^i—Co1—O7	89.81 (14)	Co1—O6—H62	128 (4)
O4—Co1—O7	88.81 (12)	H61—O6—H62	102 (5)
O4^i—Co1—O7	88.81 (12)	Co1—O7—H7	127 (4)
O5—Co1—O7	179.2 (2)	H1—N1—H2	99 (5)
O3—P1—O1	109.66 (11)	H1—N1—H3	104 (5)
O3—P1—O1^i	109.66 (11)	H2—N1—H3	128 (9)

Symmetry code: (i) −x, y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H51···O2	0.71 (2)	1.97 (3)	2.666 (6)	169 (8)
N1—H1···O4	0.81 (3)	2.29 (4)	3.010 (5)	147 (6)
O4—H41···O3^ii	0.70 (2)	2.09 (3)	2.688 (3)	143 (5)
O7—H7···O1^ii	0.71 (2)	1.94 (2)	2.642 (3)	172 (6)
O6—H61···O2^iii	0.71 (2)	1.95 (3)	2.622 (3)	158 (6)
O4—H42···O1^iv	0.71 (2)	1.95 (3)	2.629 (4)	163 (5)
O5—H52···O7^v	0.71 (2)	2.32 (2)	3.034 (6)	180 (7)
O6—H62···O1^vi	0.69 (4)	1.97 (5)	2.661 (3)	176 (6)
N1—H2···O6^vii	0.82 (3)	2.49 (3)	3.171 (6)	142 (3)
N1—H3···O3^viii	0.81 (3)	1.97 (3)	2.782 (6)	176 (9)

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