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The title compound, [Ag(C7H10N2)2]NO3·2H2O or [Ag(dmap)2]NO3·2H2O, where dmap is 4-(dimethyl­amino)­pyridine, has a distorted linear coordination geometry around the AgI ion. A novel pattern of water–nitrate hydrogen-bonded anionic strands is formed in the c direction, with the cationic [Ag(dmap)2]+ monomers trapped between them. The AgI ion and the nitrate group atoms, as well as the water mol­ecules (including the H atoms), are on a crystallographic mirror plane (Wyckoff position 4a). The influence of bulky methyl substituents in position 4 of the 4-(dimethyl­amino)­pyridine ligand on packing is discussed. The absolute structure was determined unequivocally.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109030509/fg3107sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270109030509/fg3107Isup2.hkl
Contains datablock I

CCDC reference: 749692

Comment top

Aminopyridines are water-soluble ligands which attract an intense interest owing to their versatile coordination modes, especially with AgI ions (Bowmaker et al., 2005). These type of ligands can coordinate to the metal center either via the ring N atom alone (as a monodentate ligand) or via both the ring N atom and the amine group N atom (as bridging and/or bidentate ligand). When 2-aminopyridine reacts with AgNO3 in water/ethanol solution, three compounds are formed with different stoichometric ratios, namely [Ag(2-ampy)2]NO3 (Fun et al., 2008), [Ag(2-ampy)3]NO3 and [Ag3(2-ampy)4(NO3)2]NO3 (Bowmaker et al., 2005). In the case of 3- and 4-aminopyridines, only one compound is known for each, {[Ag4(3-ampy)4(NO3)4]}n and [Ag(4-ampy)2]NO3 (Abu-Youssef et al., 2006a,b). In all the previously mentioned compounds, hydrogen bonds of the type N—H···O are formed between the amine groups of the ligands and nitrate O atoms. We have prepared the title silver(I) compound, (I), with 4-(dimethylamino)pyridine (dmap) as a continuation of our previous work on AgI compounds with pyridine-type ligands and especially aminopyridines (Abu-Youssef et al., 2006a,b; 2007).

The molecular stucture of (I) is shown in Fig. 1. The AgI ion is bonded to two dmap moieties via their pyridine N atoms, with distorted linear coordination geometry, which is the most preferred coordination geometry for AgI ions (Abu-Youssef et al., 2007; Massoud & Langer, 2009). Table 2 shows a comparison between (I) and some related aminopyridine AgI compounds. Shorter Ag—N bond distances, larger N—Ag—N bond angles and hence weaker Ag···O interactions are reported for related the linear compounds [Ag(dmap)2](PF6) (Lin et al., 2008), [Ag(4-ampy)2]NO3 (Abu-Youssef et al., 2006a) and [Ag(2-ampy)2]NO3 (Fun et al., 2008) compared with those found in (I), while for the trigonal-planar and tetrahedral compounds [Ag3(2-ampy)4(NO3)2]NO3 (Bowmaker et al., 2005) and {[Ag4(3-ampy)4(NO3)4]}n (Abu-Youssef et al., 2006b), longer Ag—N bond distances and smaller N—Ag—N bond angles are found. In the case of [Ag(dmap)2](PF6) (Lin et al., 2008), no interaction could be considered between (PF6)- and the AgI ion, where the shortest Ag···F distances are 3.007 (3) and 3.528 (6) Å.

A novel system of strong water/nitrate hydrogen bonds in (I) is shown in Fig. 2 with data in Table 1. The water/nitrate hydrogen bonds form rings [with graph-set symbol R45(12) (Bernstein et al., 1995)], forming strands propagating in the c direction. The [Ag(dmap)2]+ units are arranged in an alternating zigzag pattern between these hydrogen-bonded strands. The water/nitrate strands are also arranged in an alternating pattern above each other, with no interaction found between the successive strands. The packing scheme for (I) is shown in Fig. 3. A weak C—H···O hydrogen bond (Table 1) is found between one of the methyl groups of the dmap ligand and one of the nitrate O atoms.

No ππ interaction was found in (I), following the requirement stated by Janiak (2000).

Introducing the two methyl groups as a substituents in the amine N atom of the 4-aminopyridine ligand has greatly affected the structural features of the resulting compound (I). The bulky terminal groups of the ligand in (I) force both the nitrate and the water molecules to be arranged around the metal centres and not to be packed in between the [Ag(dmap)2]+ units as in the case of [Ag(4-ampy)2]NO3 (Abu-Youssef et al., 2006a). The nitrate anions are known for their ability to form strong hydrogen bonds, being better acceptors than the hexafluorophosphate anions in the case of [Ag(dmap)2](PF6) (Lin et al., 2008). In addition to the steric effect of the dmap ligand and the presence of nitrate groups as counter-ions, the high water content increases the possibility of formation of hydrogen bonds with the nitrate groups forming novel water/nitrate hydrogen bonded strands. This structure is very stable since different crystal morphologies were formed, which in all cases afforded the same internal order.

Related literature top

For related literature, see: Abu-Youssef, Dey, Gohar, Massoud, Öhrström & Langer (2007); Abu-Youssef, Langer & Öhrström (2006a, 2006b); Bernstein et al. (1995); Bowmaker et al. (2005); Fun et al. (2008); Janiak (2000); Lin et al. (2008); Massoud & Langer (2009).

Experimental top

To an aqueous solution (4 ml) of AgNO3 (0.169 g, 1 mmol), an ethanol solution (4 ml) of 4-(dimethylamino)pyridine (0.367 g, 1 mmol) was added. Drops of 0.1 N HNO3 were added and a brown precipitate formed, which was dissolved by stirring and heating. The final clear solution was allowed to stand for a couple of days, after which colorless crystals of different morphologies (needles, prisms, plates and cubes) suitable for X-ray measurements were collected and dried in air, with a yield of 50% with respect to the metal. Note that all the crystals have the same structure as confirmed by X-ray single-crystal analysis.

Refinement top

Aromatic H atoms were refined isotropically with Uiso(H) set at 1.2Ueq(C) and their positions were constrained to an ideal geometry using an appropriate riding model (C—H = 0.95 Å). For methyl groups, N—C—H angles (109.5°) were kept fixed, while the torsion angle was allowed to refine with the starting positions based on the circular Fourier synthesis averaged using the local threefold axis. A common Uiso(H) was refined for the methyl H atoms [final value 0.059 (4) Å2; C—H = 0.98 Å]. Water H atoms were restrained to have O—H distances of 0.88 (s.u. value?) Å with a common Uiso(H) refined [final value 0.070 (10) Å2].

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003) and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The atomic numbering scheme, with atomic displacement ellipsoids drawn at the 50% probability level; broken lines indicate hydrogen bonds (see Table 1).
[Figure 2] Fig. 2. A perspective view of (I), showing the water/nitrate hydrogen-bonded strands running in the c direction and the zigzag arrangement of [Ag(dmap)2]+. For symmetry codes see Table 1.
[Figure 3] Fig. 3. A packing diagram for (I); broken lines indicate hydrogen bonds. Note that no interaction is found between the ligands, and the water/nitrate strands run around the AgI centers.
Bis[4-(dimethylamino)pyridine-κN1]silver(I) nitrate dihydrate top
Crystal data top
[Ag(C7H10N2)2]NO3·2H2OF(000) = 920
Mr = 450.25Dx = 1.646 Mg m3
Orthorhombic, Cmc21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2c -2Cell parameters from 3205 reflections
a = 20.3572 (10) Åθ = 3.3–22.9°
b = 11.3133 (5) ŵ = 1.14 mm1
c = 7.8904 (4) ÅT = 153 K
V = 1817.22 (15) Å3Prism, colourless
Z = 40.32 × 0.17 × 0.14 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
2856 independent reflections
Radiation source: fine-focus sealed tube2268 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.062
Detector resolution: 120 pixels mm-1θmax = 30.6°, θmin = 2.1°
ω scansh = 2929
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
k = 1616
Tmin = 0.711, Tmax = 0.856l = 1111
14780 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.064 w = 1/[σ2(Fo2) + (0.0266P)2 + 0.1432P]
where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max = 0.001
2856 reflectionsΔρmax = 0.74 e Å3
137 parametersΔρmin = 0.36 e Å3
5 restraintsAbsolute structure: Flack (1983), 1330 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.06 (3)
Crystal data top
[Ag(C7H10N2)2]NO3·2H2OV = 1817.22 (15) Å3
Mr = 450.25Z = 4
Orthorhombic, Cmc21Mo Kα radiation
a = 20.3572 (10) ŵ = 1.14 mm1
b = 11.3133 (5) ÅT = 153 K
c = 7.8904 (4) Å0.32 × 0.17 × 0.14 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
2856 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
2268 reflections with I > 2σ(I)
Tmin = 0.711, Tmax = 0.856Rint = 0.062
14780 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.033H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.064Δρmax = 0.74 e Å3
S = 1.00Δρmin = 0.36 e Å3
2856 reflectionsAbsolute structure: Flack (1983), 1330 Friedel pairs
137 parametersAbsolute structure parameter: 0.06 (3)
5 restraints
Special details top

Experimental. Data were collected at 153 K using a Siemens SMART CCD diffractometer equipped with LT-2 A cooling device. A full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal–to–detector distance of 3.97 cm, 1 second per frame. Preliminary orientation matrix was obtained from the first 100 frames using SMART (Bruker, 2003). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement on the position of 3205 reflections with I>10σ(I) after integration of all the frames data using SAINT (Bruker, 2003).

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
xyzUiso*/Ueq
Ag11.00000.89370 (2)0.11483 (3)0.03393 (10)
N10.89430 (9)0.87828 (15)0.1171 (8)0.0299 (4)
C20.86131 (13)0.7975 (2)0.0259 (4)0.0305 (6)
H20.88620.74100.03570.037*
C30.79423 (13)0.7911 (2)0.0156 (4)0.0297 (6)
H30.77410.73060.04990.036*
C40.75502 (11)0.87433 (18)0.1024 (8)0.0266 (6)
C50.78948 (13)0.9585 (2)0.2002 (4)0.0302 (6)
H50.76621.01610.26380.036*
C60.85697 (15)0.9565 (2)0.2028 (4)0.0324 (6)
H60.87881.01420.26950.039*
N20.68857 (11)0.87351 (18)0.0938 (6)0.0324 (7)
C70.65486 (13)0.7824 (3)0.0028 (4)0.0417 (8)
H7A0.67200.78100.11890.059 (4)*
H7B0.60770.79940.00510.059 (4)*
H7C0.66220.70530.05060.059 (4)*
C80.64910 (14)0.9596 (3)0.1855 (4)0.0386 (7)
H8A0.65530.94860.30770.059 (4)*
H8B0.60270.94860.15700.059 (4)*
H8C0.66281.03960.15370.059 (4)*
N31.00000.8214 (3)0.6454 (5)0.0318 (11)
O11.00000.8566 (4)0.4980 (6)0.0536 (13)
O21.00000.8931 (3)0.7638 (6)0.0497 (13)
O31.00000.7134 (3)0.6755 (4)0.0561 (10)
O41.00000.5989 (4)0.9823 (5)0.0634 (14)
O51.00000.6141 (4)0.3225 (6)0.0729 (17)
H411.00000.645 (6)0.893 (7)0.070 (10)*
H421.00000.527 (2)0.948 (8)0.070 (10)*
H511.00000.622 (6)0.214 (3)0.070 (10)*
H521.00000.683 (3)0.374 (7)0.070 (10)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ag10.03155 (14)0.03464 (15)0.03561 (16)0.0000.0000.0026 (3)
N10.0321 (9)0.0299 (9)0.0277 (9)0.0018 (7)0.001 (3)0.005 (2)
C20.0353 (15)0.0272 (14)0.0288 (14)0.0044 (12)0.0049 (13)0.0016 (12)
C30.0383 (15)0.0255 (13)0.0252 (14)0.0019 (12)0.0047 (12)0.0019 (11)
C40.0331 (11)0.0281 (12)0.0185 (15)0.0031 (9)0.0022 (19)0.0032 (16)
C50.0389 (16)0.0256 (14)0.0262 (13)0.0015 (12)0.0024 (13)0.0026 (12)
C60.0469 (17)0.0257 (14)0.0245 (14)0.0036 (12)0.0011 (14)0.0026 (12)
N20.0323 (10)0.0325 (10)0.032 (2)0.0043 (8)0.0004 (14)0.0068 (13)
C70.0355 (17)0.0451 (18)0.0446 (19)0.0006 (14)0.0058 (14)0.0069 (15)
C80.0385 (17)0.0381 (17)0.0393 (17)0.0071 (13)0.0054 (14)0.0026 (13)
N30.0318 (15)0.0289 (16)0.035 (4)0.0000.0000.0004 (17)
O10.088 (3)0.048 (3)0.025 (2)0.0000.0000.004 (2)
O20.081 (3)0.042 (3)0.026 (2)0.0000.0000.0071 (16)
O30.078 (2)0.0289 (16)0.062 (3)0.0000.0000.0089 (14)
O40.113 (4)0.046 (2)0.032 (2)0.0000.0000.003 (2)
O50.152 (5)0.035 (2)0.032 (2)0.0000.0000.001 (2)
Geometric parameters (Å, º) top
Ag1—N12.1589 (18)N2—C71.454 (4)
Ag1—N1i2.1590 (18)C7—H7A0.9800
N1—C21.343 (5)C7—H7B0.9800
N1—C61.348 (5)C7—H7C0.9800
C2—C31.370 (4)C8—H8A0.9800
C2—H20.9500C8—H8B0.9800
C3—C41.412 (4)C8—H8C0.9800
C3—H30.9500N3—O11.229 (6)
C4—N21.355 (3)N3—O21.238 (5)
C4—C51.412 (5)N3—O31.245 (4)
C5—C61.374 (4)O4—H410.88 (2)
C5—H50.9500O4—H420.85 (2)
C6—H60.9500O5—H510.86 (2)
N2—C81.455 (4)O5—H520.88 (2)
N1—Ag1—N1i170.68 (10)C4—N2—C7120.2 (3)
C2—N1—C6115.7 (2)C8—N2—C7118.3 (2)
C2—N1—Ag1123.3 (3)N2—C7—H7A109.5
C6—N1—Ag1120.9 (2)N2—C7—H7B109.5
N1—C2—C3124.5 (3)H7A—C7—H7B109.5
N1—C2—H2117.7N2—C7—H7C109.5
C3—C2—H2117.7H7A—C7—H7C109.5
C2—C3—C4119.9 (3)H7B—C7—H7C109.5
C2—C3—H3120.0N2—C8—H8A109.5
C4—C3—H3120.0N2—C8—H8B109.5
N2—C4—C5121.9 (3)H8A—C8—H8B109.5
N2—C4—C3122.4 (3)N2—C8—H8C109.5
C5—C4—C3115.7 (2)H8A—C8—H8C109.5
C6—C5—C4119.6 (3)H8B—C8—H8C109.5
C6—C5—H5120.2O1—N3—O2120.1 (4)
C4—C5—H5120.2O1—N3—O3119.9 (4)
N1—C6—C5124.5 (3)O2—N3—O3120.0 (4)
N1—C6—H6117.7H41—O4—H42108 (8)
C5—C6—H6117.7H51—O5—H52112 (6)
C4—N2—C8121.5 (3)
N1i—Ag1—N1—C246 (2)C3—C4—C5—C61.3 (6)
N1i—Ag1—N1—C6138.7 (17)C2—N1—C6—C50.7 (6)
C6—N1—C2—C30.2 (6)Ag1—N1—C6—C5174.8 (3)
Ag1—N1—C2—C3175.2 (3)C4—C5—C6—N10.1 (5)
N1—C2—C3—C41.1 (5)C5—C4—N2—C80.1 (7)
C2—C3—C4—N2178.6 (4)C3—C4—N2—C8179.5 (4)
C2—C3—C4—C51.8 (6)C5—C4—N2—C7177.5 (4)
N2—C4—C5—C6179.1 (4)C3—C4—N2—C72.1 (7)
Symmetry code: (i) x+2, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H41···O30.88 (2)1.88 (3)2.746 (6)168 (8)
O4—H42···O5ii0.85 (2)1.88 (2)2.719 (6)167 (6)
O5—H51···O4iii0.86 (2)1.84 (2)2.690 (8)166 (6)
O5—H52···O10.88 (2)2.19 (2)3.074 (6)179 (6)
O5—H52···O30.88 (2)2.41 (5)3.003 (6)125 (5)
C7—H7B···O3iv0.982.623.452 (3)143
Symmetry codes: (ii) x+2, y+1, z+1/2; (iii) x, y, z1; (iv) x+3/2, y+3/2, z1/2.

Experimental details

Crystal data
Chemical formula[Ag(C7H10N2)2]NO3·2H2O
Mr450.25
Crystal system, space groupOrthorhombic, Cmc21
Temperature (K)153
a, b, c (Å)20.3572 (10), 11.3133 (5), 7.8904 (4)
V3)1817.22 (15)
Z4
Radiation typeMo Kα
µ (mm1)1.14
Crystal size (mm)0.32 × 0.17 × 0.14
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2003)
Tmin, Tmax0.711, 0.856
No. of measured, independent and
observed [I > 2σ(I)] reflections
14780, 2856, 2268
Rint0.062
(sin θ/λ)max1)0.715
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.064, 1.00
No. of reflections2856
No. of parameters137
No. of restraints5
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.74, 0.36
Absolute structureFlack (1983), 1330 Friedel pairs
Absolute structure parameter0.06 (3)

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003) and SADABS (Sheldrick, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H41···O30.88 (2)1.88 (3)2.746 (6)168 (8)
O4—H42···O5i0.853 (19)1.88 (2)2.719 (6)167 (6)
O5—H51···O4ii0.86 (2)1.84 (2)2.690 (8)166 (6)
O5—H52···O10.882 (19)2.19 (2)3.074 (6)179 (6)
O5—H52···O30.882 (19)2.41 (5)3.003 (6)125 (5)
C7—H7B···O3iii0.982.623.452 (3)143
Symmetry codes: (i) x+2, y+1, z+1/2; (ii) x, y, z1; (iii) x+3/2, y+3/2, z1/2.
Table 2. Comparison of Ag—N bond lengths (Å), N—Ag—N angles (°) and Ag···O interactions (Å) in some related silver(I) aminopyridine compounds top
CompoundAg—NN—Ag—NAg···O
[Ag(dmap)2]NO3.2H2O, (I)2.1589 (18), 2.1590 (18)170.681 (6)2.638 (4), 2.770 (5)
[Ag(dmap)2]PF6a2.119 (3)180-
[Ag(4-ampy)2]NO3b2.125 (6)173.07 (2)2.889 (6)
[Ag4(3-ampy)4(NO3)4]nc2.216 (2)/2.228 (2)/2.297 (2)/2.340 (2)/2.317 (2)/2.369 (3)/2.207 (2)124.98 (10)/126.32 (10)/140.07 (8)2.445 (3)/2.562 (3)/2.643 (2)/2.463 (2)/2.456 (3)/2.570 (2)/2.582 (2)
[Ag3(2-ampy)4(NO3)2]NO3d2.198 (3)/2.186 (3)/2.384 (3)/2.419 (3)154.122 (11)/82.617 (12)2.539 (3)/2.786 (3)
[Ag(2-ampy)3]NO3d2.222 (17)/2.232 (19)/2.396 (2)105.05 (7)/113.18 (7)/140.64 (6)2.696 (2)
[Ag(2-ampy)2]NO3e2.1406 (14)/2.1413 (14)/2.1115 (14)175.97 (6)/1802.849 (3)
References: (a) Lin et al. (2008); (b) Abu-Youssef et al. (2006a); (c) Abu-Youssef et al. (2006b); (d) Bowmaker et al. (2005); (e) Fun et al. (2008).
 

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