Bis(4-amino­pyridine)silver(I) tri­fluoro­acetate

In the title mononuclear complex, [Ag(C₅H₆N₂)₂](CF₃O₂), the Ag atom is coordinated in an almost linear configuration by the pyridine N atoms of two 4-amino­pyridine ligands. An O atom from the tri­fluoro­acetate anion weakly ligates to the Ag atom to give a T-shaped environment. In the crystal structure, the two moieties are interconnected by N—H...O hydrogen bonds and weak Ag...F interactions to form layers.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.044
• wR factor = 0.133
• Data-to-parameter ratio = 13.7

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low .....       0.98
PLAT761_ALERT_1_A CIF Contains no X-H Bonds ....................          ?
PLAT762_ALERT_1_A CIF Contains no X-Y-H or H-Y-H Angles ........          ?

Alert level C
PLAT244_ALERT_4_C Low Solvent  U(eq) as Compared to Neighbors ..          C11
PLAT244_ALERT_4_C Low Solvent  U(eq) as Compared to Neighbors ..          C12

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

   2 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
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

The coinage metals, especially silver, have been the subject of investigation for preparing novel complexes for decades. Interest in this area grew out of the diverse structural motifs displayed by these superficially similar monovalent cations. Recently, we reported several 2-aminopyrimidine complexes (Zhu, Usman et al., 2003; Zhu, Wang et al., 2003) with Ag^I atoms, which exhibit interesting bioactivities (to be reported elsewhere). We report here the crystal structure of a new 4-aminopyridinesilver(I) trifluoroacetate complex, (I).

As shown in Fig. 1, the Ag1 atom is coordinated to the pyridine N atoms of two independent 4-aminopyridine ligands. One O atom from the trifluoroacetate anion weakly ligates to the Ag atom [Ag1—O1 = 2.843 (4) Å]. The Ag—N distances [Ag1—N1 = 2.111 (4) Å and Ag1—N3 = 2.119 (4) Å] are within acceptable values but are shorter than those in the silver(I) complexes of 2-aminopyridines [2.230 (3) and 2.205 (4) Å (Zhu, Usman et al., 2003), and 2.137 (2) Å (Zhu, Wang et al., 2003)]. The bond angles [N1—Ag1—N3 = 166.5 (15)°, N1—Ag1—O1 = 94.8 (2)° and N3—Ag1—O1 = 96.2 (2)°], indicate a distorted T-shape coordination environment of atom Ag1. To reduce the steric effects the two pyridine rings connected by Ag1 are nearly perpendicular to one another, with a dihedral angle of 78.4 (2)°. All the other bond lengths and angles are in the normal ranges.

In the crystal structure of (I) (Fig. 2), discrete cations are interconnected by N—H···O hydrogen bonds to form a one-dimensional chain (see Table 1 for details). These chains are further linked by three short Ag···F contacts [Ag1—F1 = 3.414 (4) Å, Ag1—F1ⁱ = 3.376 (4) Å and Ag1—F2ⁱ = 3.593 (4) Å; symmetry code: (i) 2 − x, 2 − y, 1 − z], forming a layer-like structure (Fig. 3).

S2. Experimental

Silvertrifluoromethene sulfate and 4-aminopyridine were available commercially and were used without further purification. CF₃SO₃Ag (1.0 mmol, 257 mg) and 4-aminopyridine (1 mmol, 94 mg) were dissolved in an aqueous solution of ammonia (10 ml). The mixture was stirred for ca 10 min to obtain a clear solution. After keeping the resulting solution in air for 2 d, large colorless crystals were formed on slow evaporation of the solvents. The crystals were isolated, washed with water three times, and dried in a vacuum desiccator using CaCl₂ (yield: 69%).

S3. Refinement

All the H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with N—H distances of 0.86 Å, C—H distances of 0.97 Å and U_iso(H) = 1.2U_eq of the parent atom. The F-atom displacement parameters were quite large, presumably because these atoms were slightly disordered; however, no attempt was made to correct for this.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SMART; data reduction: SHELXTL (Sheldrick, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of the title compound, (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. The crystal packing of (I), showing the hydrogen bonds as dashed lines.
	Fig. 3. The crystal packing of (I), showing the Ag···O and Ag···F interactions as dashed lines.

Bis(4-aminopyridine)silver(I) trifluoroacetate

Crystal data

[Ag(C5H6N2)2](CF3O2)	Z = 2
Mr = 409.13	F(000) = 404
Triclinic, P1	Dx = 1.736 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 9.492 (7) Å	Cell parameters from 2092 reflections
b = 9.803 (7) Å	θ = 2.3–25.1°
c = 10.002 (7) Å	µ = 1.33 mm^−1
α = 115.206 (9)°	T = 298 K
β = 108.078 (8)°	Prism, colorless
γ = 92.793 (10)°	0.32 × 0.27 × 0.15 mm
V = 782.6 (10) Å^3

Data collection

Siemens SMART CCD area-detector diffractometer	2720 independent reflections
Radiation source: fine-focus sealed tube	2200 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
ϕ and ω scans	θmax = 25.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −11→11
Tmin = 0.676, Tmax = 0.826	k = −7→11
3984 measured reflections	l = −11→11

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.133	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0848P)^2 + 0.1491P] where P = (Fo^2 + 2Fc^2)/3
2720 reflections	(Δ/σ)max = 0.001
199 parameters	Δρmax = 0.94 e Å^−3
6 restraints	Δρmin = −0.67 e Å^−3

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
Ag1	0.85785 (4)	0.81146 (4)	0.13823 (5)	0.0720 (2)
F1	0.8563 (10)	0.9584 (8)	0.5144 (7)	0.233 (5)
F2	0.8111 (10)	0.8823 (9)	0.6519 (5)	0.220 (4)
F3	0.6613 (10)	0.9677 (10)	0.5485 (13)	0.338 (8)
N1	1.0028 (4)	0.6663 (4)	0.1821 (5)	0.0576 (9)
N2	1.3307 (5)	0.4377 (6)	0.3243 (6)	0.0788 (13)
H2A	1.3129	0.3791	0.3638	0.095*
H2B	1.4164	0.4493	0.3139	0.095*
N3	0.7608 (5)	0.9921 (5)	0.1097 (5)	0.0608 (10)
N4	0.5651 (5)	1.3482 (5)	0.0635 (5)	0.0659 (10)
H4A	0.5164	1.3381	−0.0295	0.079*
H4B	0.5724	1.4313	0.1465	0.079*
O1	0.6433 (5)	0.7312 (5)	0.2514 (4)	0.0777 (10)
O2	0.6495 (5)	0.6200 (4)	0.4028 (5)	0.0740 (10)
C1	0.9802 (6)	0.5731 (6)	0.2444 (7)	0.0656 (13)
H1	0.8873	0.5601	0.2550	0.079*
C2	1.0833 (5)	0.4973 (6)	0.2925 (6)	0.0606 (12)
H2	1.0600	0.4353	0.3350	0.073*
C3	1.2246 (5)	0.5112 (5)	0.2788 (5)	0.0546 (10)
C4	1.2474 (5)	0.6056 (6)	0.2104 (6)	0.0614 (12)
H4	1.3382	0.6182	0.1954	0.074*
C5	1.1387 (6)	0.6774 (6)	0.1668 (6)	0.0617 (12)
H5	1.1585	0.7393	0.1228	0.074*
C6	0.6847 (6)	0.9820 (6)	−0.0329 (6)	0.0568 (11)
H6	0.6752	0.8917	−0.1229	0.068*
C7	0.6196 (5)	1.0978 (5)	−0.0537 (5)	0.0557 (11)
H7	0.5694	1.0855	−0.1554	0.067*
C8	0.6299 (5)	1.2340 (5)	0.0793 (5)	0.0501 (10)
C9	0.7108 (5)	1.2446 (6)	0.2283 (5)	0.0601 (12)
H9	0.7231	1.3334	0.3208	0.072*
C10	0.7711 (6)	1.1240 (6)	0.2364 (6)	0.0647 (12)
H10	0.8230	1.1336	0.3366	0.078*
C11	0.6726 (5)	0.7286 (5)	0.3786 (5)	0.0522 (10)
C12	0.7508 (9)	0.8820 (7)	0.5228 (7)	0.0909 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.0709 (3)	0.0625 (3)	0.0866 (3)	0.0243 (2)	0.0234 (2)	0.0409 (2)
F1	0.316 (10)	0.170 (6)	0.116 (4)	−0.144 (7)	0.050 (5)	0.022 (4)
F2	0.314 (9)	0.179 (6)	0.066 (3)	−0.102 (6)	0.004 (4)	0.031 (3)
F3	0.216 (8)	0.193 (8)	0.290 (11)	0.100 (7)	0.013 (8)	−0.114 (8)
N1	0.053 (2)	0.052 (2)	0.068 (2)	0.0136 (17)	0.0181 (18)	0.030 (2)
N2	0.065 (3)	0.101 (4)	0.111 (4)	0.036 (3)	0.042 (3)	0.076 (3)
N3	0.064 (2)	0.057 (2)	0.066 (2)	0.0166 (19)	0.0238 (19)	0.033 (2)
N4	0.080 (3)	0.053 (2)	0.062 (2)	0.021 (2)	0.021 (2)	0.026 (2)
O1	0.084 (2)	0.092 (3)	0.052 (2)	0.010 (2)	0.0174 (17)	0.035 (2)
O2	0.090 (3)	0.061 (2)	0.077 (2)	0.0154 (19)	0.032 (2)	0.0357 (19)
C1	0.052 (3)	0.071 (3)	0.084 (3)	0.013 (2)	0.029 (2)	0.042 (3)
C2	0.060 (3)	0.060 (3)	0.080 (3)	0.013 (2)	0.033 (2)	0.043 (3)
C3	0.053 (2)	0.057 (3)	0.053 (2)	0.011 (2)	0.019 (2)	0.026 (2)
C4	0.055 (3)	0.073 (3)	0.070 (3)	0.014 (2)	0.028 (2)	0.042 (3)
C5	0.066 (3)	0.060 (3)	0.065 (3)	0.010 (2)	0.024 (2)	0.036 (2)
C6	0.067 (3)	0.052 (3)	0.059 (3)	0.016 (2)	0.032 (2)	0.026 (2)
C7	0.064 (3)	0.057 (3)	0.049 (2)	0.009 (2)	0.023 (2)	0.026 (2)
C8	0.050 (2)	0.048 (2)	0.055 (2)	0.0069 (19)	0.0200 (19)	0.026 (2)
C9	0.065 (3)	0.053 (3)	0.051 (2)	0.013 (2)	0.014 (2)	0.019 (2)
C10	0.066 (3)	0.065 (3)	0.055 (3)	0.012 (2)	0.011 (2)	0.029 (3)
C11	0.049 (2)	0.052 (3)	0.055 (3)	0.013 (2)	0.021 (2)	0.023 (2)
C12	0.129 (6)	0.070 (4)	0.067 (4)	0.003 (4)	0.041 (4)	0.023 (3)

Geometric parameters (Å, º)

Ag1—N1	2.111 (4)	O1—C11	1.227 (6)
Ag1—N3	2.119 (4)	O2—C11	1.212 (6)
F1—C12	1.266 (8)	C1—C2	1.351 (7)
F2—C12	1.238 (8)	C2—C3	1.395 (6)
F3—C12	1.231 (9)	C3—C4	1.408 (7)
N1—C1	1.348 (7)	C4—C5	1.344 (7)
N1—C5	1.350 (6)	C6—C7	1.380 (7)
N2—C3	1.344 (6)	C7—C8	1.398 (6)
N3—C6	1.342 (7)	C8—C9	1.405 (6)
N3—C10	1.343 (7)	C9—C10	1.360 (7)
N4—C8	1.347 (6)	C11—C12	1.507 (8)
N1—Ag1—N3	166.51 (15)	C6—C7—C8	119.5 (4)
C1—N1—C5	114.7 (4)	N4—C8—C7	121.1 (4)
C1—N1—Ag1	125.1 (3)	N4—C8—C9	122.3 (4)
C5—N1—Ag1	119.7 (3)	C7—C8—C9	116.6 (4)
C6—N3—C10	116.2 (4)	C10—C9—C8	119.5 (4)
C6—N3—Ag1	123.0 (3)	N3—C10—C9	124.5 (5)
C10—N3—Ag1	120.9 (3)	O2—C11—O1	128.9 (5)
N1—C1—C2	124.5 (4)	O2—C11—C12	116.6 (5)
C1—C2—C3	120.5 (4)	O1—C11—C12	114.5 (5)
N2—C3—C2	122.8 (4)	F3—C12—F2	103.0 (8)
N2—C3—C4	122.0 (4)	F3—C12—F1	105.1 (8)
C2—C3—C4	115.2 (4)	F2—C12—F1	102.9 (7)
C5—C4—C3	120.2 (4)	F3—C12—C11	111.4 (7)
C4—C5—N1	124.8 (5)	F2—C12—C11	117.7 (6)
N3—C6—C7	123.8 (4)	F1—C12—C11	115.2 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O2^i	0.86	2.25	2.969 (6)	142
N2—H2B···O2^ii	0.86	2.37	3.126 (7)	146
N4—H4A···O1^iii	0.86	2.05	2.887 (6)	164
N4—H4B···O2^iv	0.86	2.28	3.108 (6)	162

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