Trisilver(I) citrate

Fischer, A.

doi:10.1107/S160053681100239X

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 2| February 2011| Page m255

doi:10.1107/S160053681100239X

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Trisilver(I) citrate

Andreas Fischer ^a ^*

^aInorganic Chemistry, School of Chemical Science and Engineering, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden
^*Correspondence e-mail: afischer@kth.se

(Received 31 December 2010; accepted 17 January 2011; online 22 January 2011)

Trisilver(I) citrate, 3Ag⁺·C₆H₅O₇³⁻, was obtained by evaporation of a saturated aqueous solution of the raw material that had been obtained from sodium dihydrogen citrate and silver nitrate. It features one formula unit in the asymmetric unit. There is an intramolecular O—H⋯O hydrogen bond between the OH group and one of the terminal carboxylate groups. Different citrate groups are linked via the three Ag⁺ ions, yielding a three-dimensional network with rather irregular [AgO₄] polyhedra.

Related literature

For the preparation and structure of ammonium disilver(I) citrate monohydrate, see: Sagatys et al. (1993 ) and for tetraammonium copper(II) bis(citrate), see: Bott et al. (1991 ). For ¹⁰⁹Ag solid-state NMR studies on different silver salts, including commercial silver citrate, see: Penner & Li (2004 ).

Experimental

Crystal data

3Ag⁺·C₆H₅O₇³⁻
M_r = 512.71
Orthorhombic, P b c a
a = 6.6181 (7) Å
b = 11.8477 (11) Å
c = 22.386 (2) Å
V = 1755.3 (3) Å³
Z = 8
Mo Kα radiation
μ = 6.65 mm⁻¹
T = 299 K
0.12 × 0.05 × 0.02 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ) T_min = 0.631, T_max = 0.876
15238 measured reflections
2008 independent reflections
1493 reflections with I > 2σ(I)
R_int = 0.055

Refinement

R[F² > 2σ(F²)] = 0.032
wR(F²) = 0.051
S = 1.10
2008 reflections
148 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.21 e Å⁻³
Δρ_min = −1.21 e Å⁻³

Table 1
Selected bond lengths (Å)

Ag1—O6ⁱ	2.275 (3)
Ag1—O3	2.416 (3)
Ag1—O6ⁱⁱ	2.539 (3)
Ag1—O7ⁱⁱ	2.555 (3)
Ag2—O2ⁱⁱⁱ	2.300 (3)
Ag2—O3	2.477 (4)
Ag2—O7ⁱⁱ	2.550 (3)
Ag2—O2ⁱⁱ	2.566 (3)
Ag3—O4	2.197 (3)
Ag3—O1ⁱⁱⁱ	2.340 (3)
Ag3—O5^iv	2.404 (3)
Ag3—O4^iv	2.519 (4)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z]$ ; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ .

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5O⋯O7	0.81 (2)	1.90 (3)	2.636 (5)	152 (5)

Data collection: COLLECT (Nonius, 1998 ); cell refinement: DIRAX (Duisenberg, 1992 ); data reduction: EVALCCD (Duisenberg et al., 2003 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2007); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681100239X/kp2301sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681100239X/kp2301Isup2.hkl

checkCIF report

Comment top

The structures of many citrates of common metal ions are surprisingly sparsely investigated. Of the citrates of coinage metal cations, only ammonium disilver citrate monohydrate (Sagatys et al., 1993) and tetraammonium copper(II) bis(citrate) (Bott et al. 1991) have been reported. Here, we report the crystal structure of trisilver citrate, which was obtained from mixing solutions of sodium dihydrogen citrate and silver nitrate.

The basic structural of the 3D-polymeric structure shows an intramolecular hydrogen bond O–H···O bond between O5 and O7 (Fig. 1). As expected from the charges, all three carboxy groups are deprotonated. The coordination polyhedra about the Ag⁺ cations are quite irregular, the Ag–O distances are in the range 2.275 (3) to 2.566 (3) Å (Table 1). The Ag2–Ag3 contact of 2.8801 (6) Å is the shortest one in the structure. It can be noted that significantly shorter distances Ag⁺–Ag⁺ are observed in many silver coordination compounds.

Related literature top

For the preparation and structure of ammonium disilver(I) citrate monohydrate, see: Sagatys et al. (1993) and for tetraammonium copper(II) bis(citrate), see: Bott et al. (1991). For ¹⁰⁹Ag solid-state NMR studies on different silver salts, including commercial silver citrate, see: Penner & Li (2004).

Experimental top

An aqueous solution (0.5 mol/L) of sodium dihydrogen citrate was prepared by dissolving the respecitve amounts of trisodium citrate (Merck, p.a.) and citric acid in demineralised water. 1 mL of this solution was added to 1 mL of a solution of silver nitrate (0.5 mol/L), yielding a white precipitate. The latter was washed with demineralised water. The precipitate was then heated to 323 K with 1 mL of demineralised water. Upon cooling to room remperature, the saturated solution was filtered off and put aside for evaporation. Within a couple of days, small, colourless, rod-like crystals formed, that were suitable for structure determination. It can be noted that crystals of the title compound turned brown during the structure determination; however, no significant decrease in diffraction intensity could be observed. The initial precipitate formed from sodium dihydrogen citrate and silver nitrate was investigated by powder diffraction and it could be confirmed that it consisted of pure trisilver citrate. In addition, this powder pattern is identical with that of commercial "silver citrate hydrate".

Computing details top

Data collection: Collect; cell refinement: DIRAX (Duisenberg, 1992); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2007); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

Fig. 1. The molecular structure of the title compound. Thermal ellipsoids at the 50% probability level. H bond as dashed line.

Trisilver citrate top

Crystal data top

3Ag⁺·C₆H₅O₇³⁻	F(000) = 1904
M_r = 512.71	D_x = 3.880 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 53 reflections
a = 6.6181 (7) Å	θ = 4.0–20.0°
b = 11.8477 (11) Å	µ = 6.65 mm⁻¹
c = 22.386 (2) Å	T = 299 K
V = 1755.3 (3) Å³	Rod, colourless
Z = 8	0.12 × 0.05 × 0.02 mm

Data collection top

Bruker–Nonius KappaCCD diffractometer	1493 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.055
ϕ & ω scans	θ_max = 27.5°, θ_min = 4.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −8→8
T_min = 0.631, T_max = 0.876	k = −14→15
15238 measured reflections	l = −29→29
2008 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.032	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.051	w = 1/[σ²(F_o²) + (0.0117P)² + 5.8189P] where P = (F_o² + 2F_c²)/3
S = 1.10	(Δ/σ)_max = 0.001
2008 reflections	Δρ_max = 1.21 e Å⁻³
148 parameters	Δρ_min = −1.21 e Å⁻³
1 restraint

Crystal data top

3Ag⁺·C₆H₅O₇³⁻	V = 1755.3 (3) Å³
M_r = 512.71	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 6.6181 (7) Å	µ = 6.65 mm⁻¹
b = 11.8477 (11) Å	T = 299 K
c = 22.386 (2) Å	0.12 × 0.05 × 0.02 mm

Data collection top

Bruker–Nonius KappaCCD diffractometer	2008 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	1493 reflections with I > 2σ(I)
T_min = 0.631, T_max = 0.876	R_int = 0.055
15238 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.032	1 restraint
wR(F²) = 0.051	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	Δρ_max = 1.21 e Å⁻³
2008 reflections	Δρ_min = −1.21 e Å⁻³
148 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Ag1	0.10659 (6)	0.25916 (4)	0.431564 (16)	0.02802 (12)
Ag2	0.27992 (6)	0.15476 (4)	0.296424 (16)	0.03187 (12)
Ag3	0.42015 (6)	0.32800 (4)	0.216249 (16)	0.02955 (12)
C1	0.7295 (7)	0.5962 (4)	0.33652 (19)	0.0165 (10)
C2	0.4709 (7)	0.3885 (4)	0.3454 (2)	0.0181 (11)
C3	0.5610 (7)	0.4467 (4)	0.39995 (19)	0.0168 (10)
C4	0.7567 (7)	0.5110 (4)	0.38916 (18)	0.0155 (10)
C5	0.8155 (7)	0.5769 (4)	0.44573 (19)	0.0160 (10)
C6	1.0229 (7)	0.6305 (4)	0.4444 (2)	0.0176 (11)
O1	0.5862 (5)	0.6651 (3)	0.34287 (14)	0.0244 (8)
O2	0.8489 (5)	0.5926 (3)	0.29317 (14)	0.0240 (8)
O3	0.3092 (5)	0.3355 (3)	0.35141 (15)	0.0317 (9)
O4	0.5631 (5)	0.3974 (3)	0.29684 (14)	0.0307 (9)
O5	0.9113 (5)	0.4296 (3)	0.37668 (14)	0.0186 (7)
O6	1.0678 (5)	0.7019 (3)	0.48333 (15)	0.0296 (9)
O7	1.1480 (5)	0.6006 (3)	0.40461 (15)	0.0272 (8)
H3A	0.4617	0.4990	0.4157	0.020*
H3B	0.5856	0.3900	0.4304	0.020*
H5A	0.7161	0.6359	0.4522	0.019*
H5B	0.8089	0.5260	0.4796	0.019*
H5O	1.012 (5)	0.468 (4)	0.379 (2)	0.028*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag1	0.0264 (2)	0.0362 (3)	0.02149 (19)	0.00746 (19)	0.00281 (17)	−0.00024 (17)
Ag2	0.0284 (2)	0.0484 (3)	0.01882 (19)	−0.0047 (2)	−0.00075 (17)	−0.00654 (19)
Ag3	0.0383 (3)	0.0327 (3)	0.01763 (18)	−0.0018 (2)	−0.00653 (17)	−0.00150 (17)
C1	0.014 (2)	0.020 (3)	0.016 (2)	−0.005 (2)	−0.004 (2)	−0.003 (2)
C2	0.018 (3)	0.014 (3)	0.022 (2)	−0.002 (2)	−0.004 (2)	0.002 (2)
C3	0.014 (2)	0.021 (3)	0.015 (2)	0.001 (2)	0.0015 (19)	−0.0013 (19)
C4	0.015 (2)	0.016 (3)	0.016 (2)	0.003 (2)	0.001 (2)	0.0021 (19)
C5	0.019 (3)	0.015 (3)	0.014 (2)	0.002 (2)	0.0004 (19)	0.0012 (19)
C6	0.017 (3)	0.020 (3)	0.016 (2)	0.002 (2)	−0.004 (2)	0.003 (2)
O1	0.0250 (19)	0.023 (2)	0.0250 (17)	0.0080 (17)	0.0029 (15)	0.0076 (15)
O2	0.0222 (18)	0.034 (2)	0.0162 (16)	0.0004 (16)	0.0039 (15)	0.0037 (15)
O3	0.029 (2)	0.040 (2)	0.0260 (18)	−0.013 (2)	0.0013 (16)	−0.0050 (17)
O4	0.029 (2)	0.044 (2)	0.0188 (17)	−0.0117 (18)	0.0016 (17)	−0.0080 (16)
O5	0.0197 (19)	0.0140 (19)	0.0220 (16)	0.0030 (16)	0.0001 (15)	−0.0033 (14)
O6	0.031 (2)	0.034 (2)	0.0232 (17)	−0.0112 (18)	0.0018 (16)	−0.0115 (16)
O7	0.0223 (19)	0.030 (2)	0.0296 (19)	−0.0022 (17)	0.0038 (16)	−0.0077 (16)

Geometric parameters (Å, º) top

Ag1—O6ⁱ	2.275 (3)	C3—C4	1.522 (6)
Ag1—O3	2.416 (3)	C4—O5	1.433 (6)
Ag1—O6ⁱⁱ	2.539 (3)	C4—C5	1.538 (6)
Ag1—O7ⁱⁱ	2.555 (3)	C5—C6	1.513 (7)
Ag2—O2ⁱⁱⁱ	2.300 (3)	C6—O6	1.251 (6)
Ag2—O3	2.477 (4)	C6—O7	1.266 (6)
Ag2—O7ⁱⁱ	2.550 (3)	O1—Ag3^vi	2.340 (3)
Ag2—O2ⁱⁱ	2.566 (3)	O2—Ag2^vi	2.300 (3)
Ag2—Ag3	2.8801 (6)	O2—Ag2^vii	2.566 (3)
Ag2—Ag3^iv	3.1563 (7)	O4—Ag3^v	2.519 (4)
Ag3—O4	2.197 (3)	O5—Ag3^v	2.404 (3)
Ag3—O1ⁱⁱⁱ	2.340 (3)	O6—Ag1ⁱ	2.275 (3)
Ag3—O5^iv	2.404 (3)	O6—Ag1^vii	2.539 (3)
Ag3—O4^iv	2.519 (4)	O7—Ag2^vii	2.550 (3)
Ag3—Ag2^v	3.1563 (7)	O7—Ag1^vii	2.555 (3)
C1—O2	1.252 (5)	C3—H3A	0.9700
C1—O1	1.260 (6)	C3—H3B	0.9700
C1—C4	1.562 (6)	C5—H5A	0.9700
C2—O3	1.248 (6)	C5—H5B	0.9700
C2—O4	1.252 (6)	O5—H5O	0.81 (2)
C2—C3	1.523 (6)

O6ⁱ—Ag1—O3	145.89 (13)	O4—C2—C3	117.8 (4)
O6ⁱ—Ag1—O6ⁱⁱ	95.88 (6)	C4—C3—C2	115.6 (4)
O3—Ag1—O6ⁱⁱ	88.17 (12)	O5—C4—C3	107.6 (4)
O6ⁱ—Ag1—O7ⁱⁱ	132.00 (12)	O5—C4—C5	108.8 (4)
O3—Ag1—O7ⁱⁱ	75.34 (12)	C3—C4—C5	109.8 (3)
O6ⁱⁱ—Ag1—O7ⁱⁱ	51.10 (11)	O5—C4—C1	111.7 (3)
O2ⁱⁱⁱ—Ag2—O3	137.63 (12)	C3—C4—C1	110.2 (4)
O2ⁱⁱⁱ—Ag2—O7ⁱⁱ	144.77 (12)	C5—C4—C1	108.8 (4)
O3—Ag2—O7ⁱⁱ	74.39 (11)	C6—C5—C4	115.2 (4)
O2ⁱⁱⁱ—Ag2—O2ⁱⁱ	103.78 (10)	O6—C6—O7	121.6 (4)
O3—Ag2—O2ⁱⁱ	100.80 (12)	O6—C6—C5	119.1 (4)
O7ⁱⁱ—Ag2—O2ⁱⁱ	77.04 (10)	O7—C6—C5	119.4 (4)
O2ⁱⁱⁱ—Ag2—Ag3	78.71 (9)	C1—O1—Ag3^vi	119.0 (3)
O3—Ag2—Ag3	70.64 (8)	C1—O2—Ag2^vi	115.5 (3)
O7ⁱⁱ—Ag2—Ag3	135.29 (8)	C1—O2—Ag2^vii	124.9 (3)
O2ⁱⁱ—Ag2—Ag3	83.01 (8)	Ag2^vi—O2—Ag2^vii	106.72 (12)
O2ⁱⁱⁱ—Ag2—Ag3^iv	81.39 (9)	C2—O3—Ag1	138.1 (3)
O3—Ag2—Ag3^iv	62.71 (9)	C2—O3—Ag2	116.7 (3)
O7ⁱⁱ—Ag2—Ag3^iv	112.94 (8)	Ag1—O3—Ag2	90.13 (12)
O2ⁱⁱ—Ag2—Ag3^iv	155.01 (8)	C2—O4—Ag3	118.2 (3)
Ag3—Ag2—Ag3^iv	73.958 (16)	C2—O4—Ag3^v	122.1 (3)
O4—Ag3—O1ⁱⁱⁱ	141.33 (13)	Ag3—O4—Ag3^v	100.73 (13)
O4—Ag3—O5^iv	122.24 (13)	C4—O5—Ag3^v	121.5 (2)
O1ⁱⁱⁱ—Ag3—O5^iv	85.60 (11)	C6—O6—Ag1ⁱ	126.9 (3)
O4—Ag3—O4^iv	112.16 (13)	C6—O6—Ag1^vii	93.7 (3)
O1ⁱⁱⁱ—Ag3—O4^iv	100.76 (12)	Ag1ⁱ—O6—Ag1^vii	139.37 (15)
O5^iv—Ag3—O4^iv	73.33 (11)	C6—O7—Ag2^vii	136.0 (3)
O4—Ag3—Ag2	83.90 (9)	C6—O7—Ag1^vii	92.6 (3)
O1ⁱⁱⁱ—Ag3—Ag2	76.06 (8)	Ag2^vii—O7—Ag1^vii	85.45 (11)
O5^iv—Ag3—Ag2	152.65 (8)	C4—C3—H3A	108.4
O4^iv—Ag3—Ag2	90.16 (8)	C2—C3—H3A	108.4
O4—Ag3—Ag2^v	89.56 (10)	C4—C3—H3B	108.4
O1ⁱⁱⁱ—Ag3—Ag2^v	55.00 (8)	C2—C3—H3B	108.4
O5^iv—Ag3—Ag2^v	105.44 (8)	H3A—C3—H3B	107.4
O4^iv—Ag3—Ag2^v	155.43 (9)	C6—C5—H5A	108.5
Ag2—Ag3—Ag2^v	80.542 (17)	C4—C5—H5A	108.5
O2—C1—O1	125.8 (4)	C6—C5—H5B	108.5
O2—C1—C4	119.4 (4)	C4—C5—H5B	108.5
O1—C1—C4	114.9 (4)	H5A—C5—H5B	107.5
O3—C2—O4	123.6 (4)	C4—O5—H5O	101 (4)
O3—C2—C3	118.6 (4)	Ag3^v—O5—H5O	109 (4)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5O···O7	0.81 (2)	1.90 (3)	2.636 (5)	152 (5)

Experimental details

Crystal data
Chemical formula	3Ag⁺·C₆H₅O₇³⁻
M_r	512.71
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	299
a, b, c (Å)	6.6181 (7), 11.8477 (11), 22.386 (2)
V (Å³)	1755.3 (3)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	6.65
Crystal size (mm)	0.12 × 0.05 × 0.02

Data collection
Diffractometer	Bruker–Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.631, 0.876
No. of measured, independent and observed [I > 2σ(I)] reflections	15238, 2008, 1493
R_int	0.055
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.032, 0.051, 1.10
No. of reflections	2008
No. of parameters	148
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.21, −1.21

Computer programs: Collect, DIRAX (Duisenberg, 1992), EVALCCD (Duisenberg et al., 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2007), publCIF (Westrip, 2010).

Selected bond lengths (Å) top

Ag1—O6ⁱ	2.275 (3)	Ag2—O7ⁱⁱ	2.550 (3)
Ag1—O3	2.416 (3)	Ag2—O2ⁱⁱ	2.566 (3)
Ag1—O6ⁱⁱ	2.539 (3)	Ag3—O4	2.197 (3)
Ag1—O7ⁱⁱ	2.555 (3)	Ag3—O1ⁱⁱⁱ	2.340 (3)
Ag2—O2ⁱⁱⁱ	2.300 (3)	Ag3—O5^iv	2.404 (3)
Ag2—O3	2.477 (4)	Ag3—O4^iv	2.519 (4)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+3/2, y−1/2, z; (iii) −x+1, y−1/2, −z+1/2; (iv) x−1/2, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5O···O7	0.81 (2)	1.90 (3)	2.636 (5)	152 (5)

Acknowledgements

The Swedish Research Council (VR) is acknowledged for providing funding for the single-crystal diffractometer.

References

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