Bis­[aqua(4-chloro­benzoato)silver(I)](Ag—Ag)

The title compound, [Ag₂(C₇H₆ClO₃)₂(H₂O)₂], is a centrosymmetric dimeric complex held together by a short Ag...Ag contact. The Ag^I atom is coordinated by two O atoms, one from the water mol­ecule and the other from the benzoate moiety, in a nearly linear geometry. The crystal structure is composed of molecular columns which are stabilized by two types of O—H...O hydrogen bonds. Intermolecular Ag...Ag and Ag...O short contacts are also observed.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.010 Å
• R factor = 0.055
• wR factor = 0.130
• Data-to-parameter ratio = 19.6

checkCIF results

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S1. Comment

The study of the structures and properties of d-metal-carboxylates is an important research branch of chemistry. Among different `hot' topics currently being studied, silver(I)–carboxylate complexes have been widely reported (Zhu et al., 1999; Zheng, Tong, Zhu & Chen, 2001; Zheng, Tong, Zhu, Fang & Chen, 2001). In these studies, we have reported and structurally characterized a few silver(I) complexes containing carboxylate anions; some of the complexes have special properties. Recently, we reported the crystal structure of a silver complex with 4-fluorobenzoate, and it was found that this complex has significant antitumor activity (Zhu et al., 2003). We have also prepared an analogous silver(I)-carboxylate complex, viz. the title compound, (I), whose crystal structure is reported here.

In the title complex, the Ag atom is coordinated by two O atoms, one from the water molecule and the other from the benzoate moiety, in a nearly linear geometry, O1—Ag1—O1W being 174.1 (2) Å. The Ag—O bond distances [Ag1—O1 2.103 (5) Å and Ag1—O1W 2.109 (5) Å] are significantly shorter than those in other silver(I) complexes with terephthalate [2.175 (3)–2.191 (2) Å; Zhu et al., 2003]. The benzoate moiety is planar with the carboxylate O atoms deviating by −0.027 (5) Å (O1) and −0.031 (6) Å (O2) from the mean plane.

The asymmetric unit consists of one half of the dimeric complex (Fig. 1), the other half being generated by an inversion center. The dimer is held together by a short Ag···Ag(-x, 1 − y, −z) contact [3.118 (1) Å]. This contact is much shorter than that in the silver(I) complexes with terephthalate [3.489 (7) Å].

In the crystal structure, the molecules are interconnected, in columns parallel to b, by intermolecular O1W—H1W···O2ⁱ and O1W—H2W···O2ⁱⁱ hydrogen bonds (Fig. 2; for symmetry codes see Table 2). The molecular columns are further interconnected by intermolecular Ag···Ag and Ag···O short-contacts (Table 3).

S2. Experimental

Ag₂O (0.5 mmol, 116 mg) and 4-chlorobenzoic acid (1 mmol, 156 mg) were dissolved in aqueous ammonia (10 ml), stirring for ca 10 min to obtain a clear solution. After the solution had stood in air for two days with ammonia gas escaping, colorless crystals were deposited, collected and washed with water. These crystals were then dried in a vacuum desiccator under drying CaCl₂ (yield 66%). Analysis of the title complex (C₁₄H₁₂AgCl₂O₆) calculated: C 29.87, H 2.15%; found: C 30.05, H 2.18%. A single-crystal of suitable size was used for the X-ray diffraction study.

S3. Refinement

All H atoms were geometrically fixed with C—H = 0.93 Å and O—H = 0.94–1.00 Å. They were treated as riding atoms with U_iso(H) = 1.2U_eq(C) and U_iso(H) = 1.5U_eq(O). The maximum and minimum electron-density peaks are located at 1.00 and 1.19 Å from Ag1 and H2W, respectively.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 1990).

Figures

	Fig. 1. The structure of the title complex showing 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. Packing diagram of the complex viewed down the b axis, showing the column formation. The dashed lines denote the O—H···O intermolecular interactions and Ag···Ag short contacts.

Bis[aqua(4-chlorobenzoato)silver(I)]

Crystal data

[Ag2(C7H6ClO3)2(H2O)2]	F(000) = 1088
Mr = 562.88	Dx = 2.139 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 35.978 (5) Å	Cell parameters from 1762 reflections
b = 4.0535 (6) Å	θ = 3.3–28.3°
c = 12.3204 (19) Å	µ = 2.57 mm^−1
β = 103.439 (3)°	T = 293 K
V = 1747.6 (5) Å^3	Block, colorless
Z = 4	0.40 × 0.20 × 0.20 mm

Data collection

Siemens SMART CCD area-detector diffractometer	2139 independent reflections
Radiation source: fine-focus sealed tube	1343 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
Detector resolution: 8.33 pixels mm^-1	θmax = 28.3°, θmin = 3.3°
ω scans	h = −47→29
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −5→5
Tmin = 0.426, Tmax = 0.627	l = −15→16
5101 measured reflections

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)] = 0.055	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.130	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0473P)^2 + 8.4499P] where P = (Fo^2 + 2Fc^2)/3
2139 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 1.09 e Å^−3
0 restraints	Δρmin = −0.57 e Å^−3

Special details

Experimental. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 88 and 180°) for the crystal and each exposure of 10 s covered 0.3° in ω. The crystal-to-detector distance was 5 cm and the detector swing angle was −35°. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the intensity of duplicate reflections, and was found to be negligible.

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
Ag1	0.008337 (15)	0.27127 (15)	0.10458 (4)	0.0589 (2)
Cl1	0.23476 (6)	−0.5091 (5)	0.1096 (2)	0.0790 (6)
O1	0.06162 (13)	0.1284 (14)	0.0772 (4)	0.0623 (13)
O2	0.07161 (16)	−0.0847 (14)	0.2451 (4)	0.0734 (16)
O1W	−0.04703 (15)	0.4190 (15)	0.1140 (4)	0.0741 (14)
H1W	−0.0591	0.2198	0.1242	0.111*
H2W	−0.0441	0.5983	0.1709	0.111*
C1	0.13266 (18)	−0.0794 (17)	0.0503 (5)	0.0485 (15)
H1	0.1170	0.0369	−0.0078	0.058*
C2	0.1682 (2)	−0.1888 (17)	0.0399 (6)	0.0533 (17)
H2	0.1766	−0.1440	−0.0246	0.064*
C3	0.19080 (19)	−0.3620 (16)	0.1246 (6)	0.0511 (16)
C4	0.1795 (2)	−0.4225 (17)	0.2228 (6)	0.0574 (17)
H4	0.1954	−0.5366	0.2809	0.069*
C5	0.14458 (19)	−0.3118 (16)	0.2327 (6)	0.0505 (16)
H5	0.1369	−0.3508	0.2985	0.061*
C6	0.12044 (17)	−0.1427 (15)	0.1467 (5)	0.0413 (14)
C7	0.08203 (18)	−0.0275 (15)	0.1578 (5)	0.0466 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.0505 (3)	0.0795 (4)	0.0498 (3)	0.0078 (3)	0.0182 (2)	0.0080 (3)
Cl1	0.0561 (11)	0.0736 (14)	0.1169 (17)	0.0053 (9)	0.0398 (11)	−0.0058 (12)
O1	0.050 (3)	0.090 (4)	0.048 (3)	0.013 (3)	0.013 (2)	0.008 (3)
O2	0.095 (4)	0.079 (4)	0.064 (3)	0.027 (3)	0.053 (3)	0.024 (3)
O1W	0.078 (4)	0.077 (4)	0.073 (4)	−0.006 (3)	0.031 (3)	−0.005 (3)
C1	0.051 (4)	0.055 (4)	0.042 (3)	−0.002 (3)	0.015 (3)	0.002 (3)
C2	0.057 (4)	0.057 (4)	0.054 (4)	−0.010 (3)	0.029 (3)	−0.006 (3)
C3	0.053 (4)	0.040 (3)	0.066 (4)	−0.006 (3)	0.025 (3)	−0.009 (3)
C4	0.057 (4)	0.049 (4)	0.065 (4)	0.007 (3)	0.012 (3)	0.006 (3)
C5	0.059 (4)	0.049 (4)	0.047 (3)	−0.003 (3)	0.017 (3)	0.004 (3)
C6	0.045 (3)	0.041 (3)	0.040 (3)	−0.006 (3)	0.014 (3)	−0.003 (3)
C7	0.052 (4)	0.041 (4)	0.050 (4)	−0.001 (3)	0.019 (3)	−0.003 (3)

Geometric parameters (Å, º)

Ag1—O1	2.103 (5)	C1—H1	0.9300
Ag1—O1W	2.109 (5)	C2—C3	1.360 (10)
Ag1—Ag1^i	3.118 (1)	C2—H2	0.9300
Cl1—C3	1.740 (7)	C3—C4	1.384 (9)
O1—C7	1.259 (8)	C4—C5	1.366 (9)
O2—C7	1.240 (7)	C4—H4	0.9300
O1W—H1W	0.9387	C5—C6	1.385 (9)
O1W—H2W	0.9981	C5—H5	0.9300
C1—C6	1.383 (8)	C6—C7	1.495 (8)
C1—C2	1.389 (9)
O1—Ag1—O1W	174.1 (2)	C2—C3—C4	121.2 (6)
O1—Ag1—Ag1^i	92.2 (1)	C2—C3—Cl1	119.4 (5)
O1W—Ag1—Ag1^i	82.8 (2)	C4—C3—Cl1	119.4 (6)
O1—Ag1—Ag1^ii	72.6 (1)	C5—C4—C3	118.9 (7)
O1W—Ag1—Ag1^ii	103.1 (2)	C5—C4—H4	120.6
Ag1^i—Ag1—Ag1^ii	77.76 (3)	C3—C4—H4	120.6
C7—O1—Ag1	113.5 (4)	C4—C5—C6	121.4 (6)
Ag1—O1W—H1W	103.6	C4—C5—H5	119.3
Ag1—O1W—H2W	107.3	C6—C5—H5	119.3
H1W—O1W—H2W	120.6	C1—C6—C5	118.7 (6)
C6—C1—C2	120.3 (6)	C1—C6—C7	120.4 (6)
C6—C1—H1	119.8	C5—C6—C7	120.9 (6)
C2—C1—H1	119.8	O2—C7—O1	122.6 (6)
C3—C2—C1	119.5 (6)	O2—C7—C6	119.5 (6)
C3—C2—H2	120.3	O1—C7—C6	117.9 (5)
C1—C2—H2	120.3
Ag1^i—Ag1—O1—C7	169.0 (5)	C2—C1—C6—C7	−179.5 (6)
Ag1^ii—Ag1—O1—C7	−114.6 (5)	C4—C5—C6—C1	−1.6 (10)
C6—C1—C2—C3	0.7 (10)	C4—C5—C6—C7	179.0 (6)
C1—C2—C3—C4	−2.1 (10)	Ag1—O1—C7—O2	−1.1 (8)
C1—C2—C3—Cl1	178.1 (5)	Ag1—O1—C7—C6	179.6 (4)
C2—C3—C4—C5	1.6 (10)	C1—C6—C7—O2	−179.6 (6)
Cl1—C3—C4—C5	−178.6 (5)	C5—C6—C7—O2	−0.1 (9)
C3—C4—C5—C6	0.3 (10)	C1—C6—C7—O1	−0.3 (9)
C2—C1—C6—C5	1.0 (10)	C5—C6—C7—O1	179.1 (6)

Symmetry codes: (i) −x, −y+1, −z; (ii) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W···O2^iii	0.94	2.16	2.946 (8)	141
O1W—H2W···O2^iv	1.00	2.04	2.925 (8)	146

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