Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270105000806/fa1102sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270105000806/fa1102Isup2.hkl |
CCDC reference: 268080
1-Allyl-3-aminopyridinium chloride was prepared from 3-aminopyridine (Aldrich) by a procedure similar to that used for obtaining 1-allyl-4-aminopyridinium chloride (Goreshnik et al., 2003a). Good quality crystals of the title compound were obtained using the alternating-current electrochemical technique (Mykhalichko & Mys'kiv, 1998) starting from 1-allyl-3-aminopyridinium chloride and copper(II) chloride. To an ethanol solution (2 ml) of CuCl2.2H2O (1 mmol) was added an ethanol solution (2 ml) of 1-allyl-3-aminopyridinium chloride (1.2 mmol). The solution was placed into a small test tube and copper-wire electrodes in cork were inserted. After applying 0.30 V alternating current (frequency 50 Hz) for some days, colorless crystals of the title compound appeared on the copper electrodes. The density, measured by flotation in a chloroform–bromoform mixture, is 2.0 Mg m3.
The highest difference peak is located 0.92 Å from atom Cu1. All H atoms were allowed to ride on their parent atoms [C—H = 0.93 and 0.97 \%A and Uiso(H) = 1.2Ueq(C,N)].
Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: Corinc (Dräger & Gattow, 1971); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Diamond (Bergerhoff, 1996); software used to prepare material for publication: enCIFer (Allen et al., 2004).
Fig. 1. Copper–chloro chains and ligands in the structure of (I). | |
Fig. 2. Hydrogen-bonding in the structure of (I). |
[Cu4Cl6(C8H11N2)2] | Z = 1 |
Mr = 737.24 | F(000) = 364 |
Triclinic, P1 | Dx = 2.020 Mg m−3 Dm = 2.000 Mg m−3 Dm measured by flotation |
Hall symbol: -P 1 | Cu Kα radiation, λ = 1.54178 Å |
a = 8.4148 (12) Å | Cell parameters from 25 reflections |
b = 8.7310 (16) Å | θ = 35–45° |
c = 9.8916 (16) Å | µ = 10.14 mm−1 |
α = 102.177 (16)° | T = 295 K |
β = 104.587 (12)° | Plate, colourless |
γ = 113.166 (13)° | 0.24 × 0.20 × 0.04 mm |
V = 606.1 (2) Å3 |
Enraf–Nonius CAD-4 diffractometer | 2004 reflections with I > 2σ(I) |
Radiation source: rotating anode | Rint = 0.106 |
Graphite monochromator | θmax = 73.4°, θmin = 4.9° |
θ/2ω scans | h = −10→0 |
Absorption correction: numerical (de Meulenaer & Tompa, 1965) | k = −9→10 |
Tmin = 0.19, Tmax = 0.696 | l = −11→12 |
2615 measured reflections | 3 standard reflections every 60 min |
2443 independent reflections | intensity decay: 5% |
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)] = 0.060 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.175 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.1252P)2 + 0.1886P] where P = (Fo2 + 2Fc2)/3 |
2443 reflections | (Δ/σ)max < 0.001 |
136 parameters | Δρmax = 1.28 e Å−3 |
0 restraints | Δρmin = −0.95 e Å−3 |
[Cu4Cl6(C8H11N2)2] | γ = 113.166 (13)° |
Mr = 737.24 | V = 606.1 (2) Å3 |
Triclinic, P1 | Z = 1 |
a = 8.4148 (12) Å | Cu Kα radiation |
b = 8.7310 (16) Å | µ = 10.14 mm−1 |
c = 9.8916 (16) Å | T = 295 K |
α = 102.177 (16)° | 0.24 × 0.20 × 0.04 mm |
β = 104.587 (12)° |
Enraf–Nonius CAD-4 diffractometer | 2004 reflections with I > 2σ(I) |
Absorption correction: numerical (de Meulenaer & Tompa, 1965) | Rint = 0.106 |
Tmin = 0.19, Tmax = 0.696 | 3 standard reflections every 60 min |
2615 measured reflections | intensity decay: 5% |
2443 independent reflections |
R[F2 > 2σ(F2)] = 0.060 | 0 restraints |
wR(F2) = 0.175 | H-atom parameters constrained |
S = 1.06 | Δρmax = 1.28 e Å−3 |
2443 reflections | Δρmin = −0.95 e Å−3 |
136 parameters |
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. A full-matrix least-squares refinement based on F2 was carried out for the positional and thermal parameters for all atoms, anisotropic mode of the refinement - excluding H-atoms. The highest peak is located 0.92 Å from Cu1. For H atoms in NH2 group the coordinates 'ride' on the coordinates of the N atom. The same shifts are applied to the coordinates of all three atoms, and all of them contribute to the derivative calculation. Hydrogen atoms of pyridine ring refined as a a riding model. |
x | y | z | Uiso*/Ueq | ||
Cu1 | 0.37372 (10) | 0.08635 (10) | 0.55036 (8) | 0.0357 (3) | |
Cu2 | 0.83984 (13) | 0.32969 (13) | 0.47343 (11) | 0.0541 (3) | |
Cl1 | 0.67770 (15) | 0.28543 (16) | 0.64312 (13) | 0.0356 (3) | |
Cl2 | 0.68444 (17) | 0.04525 (17) | 0.28167 (13) | 0.0413 (3) | |
Cl3 | 0.83960 (16) | 0.55051 (16) | 0.37308 (14) | 0.0389 (3) | |
N1 | 0.2456 (5) | 0.2954 (5) | 0.2040 (4) | 0.0320 (8) | |
C2 | 0.0691 (7) | 0.2630 (7) | 0.1697 (5) | 0.0375 (10) | |
H2 | 0.0103 | 0.2350 | 0.2356 | 0.045* | |
C3 | −0.0290 (7) | 0.2704 (7) | 0.0370 (6) | 0.0394 (11) | |
C4 | 0.0648 (9) | 0.3151 (8) | −0.0560 (6) | 0.0507 (14) | |
H4 | 0.0059 | 0.3270 | −0.1433 | 0.061* | |
C5 | 0.2467 (10) | 0.3425 (10) | −0.0204 (7) | 0.0614 (18) | |
H5 | 0.3082 | 0.3688 | −0.0851 | 0.074* | |
C6 | 0.3352 (8) | 0.3305 (9) | 0.1112 (6) | 0.0489 (14) | |
H6 | 0.4563 | 0.3466 | 0.1355 | 0.059* | |
N7 | −0.2074 (8) | 0.2375 (9) | 0.0043 (6) | 0.0629 (15) | |
H7A | −0.2639 | 0.2213 | −0.0841 | 0.076* | |
H7B | −0.2432 | 0.2122 | 0.0814 | 0.076* | |
C8 | 0.3429 (6) | 0.2873 (6) | 0.3489 (5) | 0.0319 (9) | |
H8A | 0.3258 | 0.3572 | 0.4288 | 0.038* | |
H8B | 0.4753 | 0.3370 | 0.3691 | 0.038* | |
C9 | 0.2662 (6) | 0.0981 (6) | 0.3431 (5) | 0.0311 (9) | |
H9 | 0.3168 | 0.0295 | 0.3054 | 0.037* | |
C10 | 0.1274 (7) | 0.0235 (7) | 0.3901 (5) | 0.0350 (10) | |
H10A | 0.0749 | 0.0897 | 0.4281 | 0.042* | |
H10B | 0.0840 | −0.0943 | 0.3845 | 0.042* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu1 | 0.0288 (4) | 0.0416 (5) | 0.0373 (4) | 0.0128 (3) | 0.0123 (3) | 0.0222 (3) |
Cu2 | 0.0447 (5) | 0.0533 (6) | 0.0653 (6) | 0.0175 (4) | 0.0214 (4) | 0.0326 (5) |
Cl1 | 0.0250 (5) | 0.0389 (6) | 0.0410 (6) | 0.0095 (5) | 0.0124 (4) | 0.0212 (5) |
Cl2 | 0.0356 (6) | 0.0434 (7) | 0.0396 (6) | 0.0088 (5) | 0.0152 (5) | 0.0228 (5) |
Cl3 | 0.0270 (6) | 0.0406 (6) | 0.0487 (6) | 0.0099 (5) | 0.0140 (5) | 0.0269 (5) |
N1 | 0.030 (2) | 0.0293 (19) | 0.0306 (18) | 0.0053 (16) | 0.0117 (16) | 0.0168 (15) |
C2 | 0.037 (3) | 0.042 (3) | 0.035 (2) | 0.016 (2) | 0.015 (2) | 0.020 (2) |
C3 | 0.039 (3) | 0.035 (2) | 0.036 (2) | 0.014 (2) | 0.006 (2) | 0.013 (2) |
C4 | 0.059 (4) | 0.050 (3) | 0.033 (2) | 0.018 (3) | 0.007 (2) | 0.023 (2) |
C5 | 0.055 (4) | 0.082 (5) | 0.043 (3) | 0.017 (3) | 0.022 (3) | 0.039 (3) |
C6 | 0.033 (3) | 0.064 (4) | 0.047 (3) | 0.012 (3) | 0.018 (2) | 0.030 (3) |
N7 | 0.048 (3) | 0.091 (4) | 0.051 (3) | 0.036 (3) | 0.008 (2) | 0.034 (3) |
C8 | 0.024 (2) | 0.033 (2) | 0.031 (2) | 0.0058 (18) | 0.0074 (17) | 0.0148 (17) |
C9 | 0.032 (2) | 0.035 (2) | 0.033 (2) | 0.0170 (19) | 0.0114 (18) | 0.0206 (18) |
C10 | 0.031 (2) | 0.031 (2) | 0.040 (2) | 0.0100 (19) | 0.0096 (19) | 0.021 (2) |
Cu1—C10 | 2.048 (5) | C3—C4 | 1.378 (8) |
Cu1—C9 | 2.064 (4) | C4—C5 | 1.389 (10) |
Cu1—Cl1 | 2.2478 (14) | C4—H4 | 0.9300 |
Cu1—Cl2i | 2.2568 (14) | C5—C6 | 1.375 (8) |
Cu2—Cl3 | 2.3477 (15) | C5—H5 | 0.9300 |
Cu2—Cl2 | 2.3841 (18) | C6—H6 | 0.9300 |
Cu2—Cl3ii | 2.3922 (16) | N7—H7A | 0.8344 |
Cu2—Cl1 | 2.4167 (15) | N7—H7B | 0.9251 |
Cu2—Cu2ii | 2.9506 (19) | C8—C9 | 1.501 (6) |
N1—C2 | 1.333 (7) | C8—H8A | 0.9700 |
N1—C6 | 1.338 (7) | C8—H8B | 0.9700 |
N1—C8 | 1.492 (5) | C9—C10 | 1.344 (7) |
C2—C3 | 1.392 (7) | C9—H9 | 0.9300 |
C2—H2 | 0.9300 | C10—H10A | 0.9300 |
C3—N7 | 1.348 (8) | C10—H10B | 0.9300 |
C10—Cu1—C9 | 38.15 (19) | C3—C4—H4 | 119.8 |
C10—Cu1—Cl1 | 140.52 (14) | C5—C4—H4 | 119.8 |
C9—Cu1—Cl1 | 105.51 (14) | C6—C5—C4 | 119.5 (6) |
C10—Cu1—Cl2i | 109.63 (14) | C6—C5—H5 | 120.3 |
C9—Cu1—Cl2i | 146.35 (14) | C4—C5—H5 | 120.3 |
Cl1—Cu1—Cl2i | 108.12 (5) | N1—C6—C5 | 119.4 (5) |
Cl3—Cu2—Cl2 | 110.82 (6) | N1—C6—H6 | 120.3 |
Cl3—Cu2—Cl3ii | 103.01 (5) | C5—C6—H6 | 120.3 |
Cl2—Cu2—Cl3ii | 119.73 (6) | C3—N7—H7A | 114.6 |
Cl3—Cu2—Cl1 | 115.89 (6) | C3—N7—H7B | 108.7 |
Cl2—Cu2—Cl1 | 103.51 (5) | H7A—N7—H7B | 134.7 |
Cl3ii—Cu2—Cl1 | 104.32 (5) | N1—C8—C9 | 109.9 (4) |
Cl3—Cu2—Cu2ii | 52.18 (4) | N1—C8—H8A | 109.7 |
Cl2—Cu2—Cu2ii | 133.23 (6) | C9—C8—H8A | 109.7 |
Cl3ii—Cu2—Cu2ii | 50.83 (4) | N1—C8—H8B | 109.7 |
Cl1—Cu2—Cu2ii | 123.23 (7) | C9—C8—H8B | 109.7 |
Cu1—Cl1—Cu2 | 118.67 (6) | H8A—C8—H8B | 108.2 |
Cu1i—Cl2—Cu2 | 89.96 (5) | C10—C9—C8 | 122.8 (4) |
Cu2—Cl3—Cu2ii | 76.99 (5) | C10—C9—H9 | 118.6 |
C2—N1—C6 | 121.9 (4) | C8—C9—H9 | 118.6 |
C2—N1—C8 | 118.4 (4) | C10—C9—Cu1 | 70.3 (3) |
C6—N1—C8 | 119.6 (4) | C8—C9—Cu1 | 110.6 (3) |
N1—C2—C3 | 121.3 (5) | C9—C10—Cu1 | 71.6 (3) |
N1—C2—H2 | 119.3 | C9—C10—H10A | 120.0 |
C3—C2—H2 | 119.3 | Cu1—C10—H10A | 109.5 |
N7—C3—C4 | 122.3 (5) | C9—C10—H10B | 120.0 |
N7—C3—C2 | 120.5 (5) | Cu1—C10—H10B | 89.0 |
C4—C3—C2 | 117.2 (5) | H10A—C10—H10B | 120.0 |
C3—C4—C5 | 120.5 (5) | ||
C10—Cu1—Cl1—Cu2 | −52.9 (3) | N7—C3—C4—C5 | −177.9 (7) |
C9—Cu1—Cl1—Cu2 | −34.05 (16) | C2—C3—C4—C5 | 3.1 (9) |
Cl2i—Cu1—Cl1—Cu2 | 144.79 (6) | C3—C4—C5—C6 | −2.2 (11) |
Cl3—Cu2—Cl1—Cu1 | 90.30 (8) | C2—N1—C6—C5 | 3.3 (9) |
Cl2—Cu2—Cl1—Cu1 | −31.23 (8) | C8—N1—C6—C5 | −178.3 (6) |
Cl3ii—Cu2—Cl1—Cu1 | −157.23 (6) | C4—C5—C6—N1 | −1.1 (11) |
Cu2ii—Cu2—Cl1—Cu1 | 150.51 (6) | C2—N1—C8—C9 | 71.2 (6) |
Cl3—Cu2—Cl2—Cu1i | −156.23 (6) | C6—N1—C8—C9 | −107.3 (5) |
Cl3ii—Cu2—Cl2—Cu1i | 84.13 (6) | N1—C8—C9—C10 | −93.3 (5) |
Cl1—Cu2—Cl2—Cu1i | −31.35 (6) | N1—C8—C9—Cu1 | −172.6 (3) |
Cu2ii—Cu2—Cl2—Cu1i | 146.65 (7) | Cl1—Cu1—C9—C10 | −160.6 (3) |
Cl2—Cu2—Cl3—Cu2ii | −129.23 (7) | Cl2i—Cu1—C9—C10 | 21.4 (4) |
Cl3ii—Cu2—Cl3—Cu2ii | 0.0 | C10—Cu1—C9—C8 | 118.6 (5) |
Cl1—Cu2—Cl3—Cu2ii | 113.23 (7) | Cl1—Cu1—C9—C8 | −42.0 (3) |
C6—N1—C2—C3 | −2.3 (8) | Cl2i—Cu1—C9—C8 | 140.0 (3) |
C8—N1—C2—C3 | 179.3 (5) | C8—C9—C10—Cu1 | −102.3 (4) |
N1—C2—C3—N7 | −179.9 (5) | Cl1—Cu1—C10—C9 | 30.2 (4) |
N1—C2—C3—C4 | −1.0 (8) | Cl2i—Cu1—C10—C9 | −167.6 (3) |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+2, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N7—H7A···Cl1iii | 0.83 | 2.83 | 3.618 (5) | 158 |
N7—H7B···Cl2iv | 0.93 | 2.75 | 3.629 (6) | 160 |
Symmetry codes: (iii) x−1, y, z−1; (iv) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | [Cu4Cl6(C8H11N2)2] |
Mr | 737.24 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 295 |
a, b, c (Å) | 8.4148 (12), 8.7310 (16), 9.8916 (16) |
α, β, γ (°) | 102.177 (16), 104.587 (12), 113.166 (13) |
V (Å3) | 606.1 (2) |
Z | 1 |
Radiation type | Cu Kα |
µ (mm−1) | 10.14 |
Crystal size (mm) | 0.24 × 0.20 × 0.04 |
Data collection | |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | Numerical (de Meulenaer & Tompa, 1965) |
Tmin, Tmax | 0.19, 0.696 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2615, 2443, 2004 |
Rint | 0.106 |
(sin θ/λ)max (Å−1) | 0.621 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.060, 0.175, 1.06 |
No. of reflections | 2443 |
No. of parameters | 136 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.28, −0.95 |
Computer programs: CAD-4 Software (Enraf–Nonius, 1989), CAD-4 Software, Corinc (Dräger & Gattow, 1971), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 1997), Diamond (Bergerhoff, 1996), enCIFer (Allen et al., 2004).
Cu1—C10 | 2.048 (5) | Cu2—Cl3ii | 2.3922 (16) |
Cu1—C9 | 2.064 (4) | Cu2—Cl1 | 2.4167 (15) |
Cu1—Cl1 | 2.2478 (14) | N1—C8 | 1.492 (5) |
Cu1—Cl2i | 2.2568 (14) | C8—C9 | 1.501 (6) |
Cu2—Cl3 | 2.3477 (15) | C9—C10 | 1.344 (7) |
Cu2—Cl2 | 2.3841 (18) | ||
C10—Cu1—C9 | 38.15 (19) | Cl2—Cu2—Cl1 | 103.51 (5) |
Cl1—Cu1—Cl2i | 108.12 (5) | Cl3ii—Cu2—Cl1 | 104.32 (5) |
Cl3—Cu2—Cl2 | 110.82 (6) | C2—N1—C8 | 118.4 (4) |
Cl3—Cu2—Cl3ii | 103.01 (5) | C6—N1—C8 | 119.6 (4) |
Cl2—Cu2—Cl3ii | 119.73 (6) | N1—C8—C9 | 109.9 (4) |
Cl3—Cu2—Cl1 | 115.89 (6) | C10—C9—C8 | 122.8 (4) |
C2—N1—C8—C9 | 71.2 (6) | Cl1—Cu1—C9—C10 | −160.6 (3) |
C6—N1—C8—C9 | −107.3 (5) | Cl2i—Cu1—C9—C10 | 21.4 (4) |
N1—C8—C9—C10 | −93.3 (5) |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+2, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N7—H7A···Cl1iii | 0.83 | 2.83 | 3.618 (5) | 158 |
N7—H7B···Cl2iv | 0.93 | 2.75 | 3.629 (6) | 160 |
Symmetry codes: (iii) x−1, y, z−1; (iv) x−1, y, z. |
π-complexes involving heterocyclic ligands have been investigated poorly. There have been only a few publications referring to copper(I) π-complexation with pyridine derivatives (for example, Munakata et al., 1987). The importance of metal complexes with heterocyclic ligands as compounds with potential biological activity (Ghiladi et al., 2001; Rhames et al., 2001) has led us to pursue a structural investigation of the copper(I) π-complexes with 1-allyl-4-aminopyridinium (Goreshnik et al., 2003a) and 1-allyl-2-aminopyridinium (Goreshnik et al., 2003b) cations. To complete the comparison of structural peculiarities of complexes with isomeric N-allylaminopyridinium cations, the copper(I) chloride π-complex, (I), with the 1-allyl-3-aminopyridinium cation has been obtained and structurally investigated.
The Cu and Cl atoms in (I) form infinite chains, propagating along [110]. These chains are composed of 4- and 8-membered cyclic subunits, with a common apex at atom Cu2 (Fig. 1). Both of the cyclic subunits are centrosymmetric; the four-membered cycle is essentially planar, while the eight-membered ring has a chair-like conformation. All Cl atoms act as bridges; atoms Cl1 and Cl2 connect pairs of Cu1 and Cu2 atoms in the eight-membered rings, whereas atom Cl3 bridges two Cu2 atoms in the four-membered ring. Atom Cu2 is tetrahedrally surrounded by four Cl atoms, whereas the trigonal-planar arrangement about atom Cu1 includes two Cl atoms and the olefinic bond of the allyl group of the 1-allyl-3-aminopyridinium ligand (Table 1). Because the coordination number is lower for atom Cu1 than for atom Cu2, the Cu1—Cl distances, of 2.2478 (14) and 2.2568 (14) Å, are noticeably shorter than the Cu2—Cl distances [2.3477 (15) – 2.4167 (15) Å].
For a numerical characterization of the effectiveness of the copper(I)-olefin interaction, the C—Cu—C angle provides the most suitable parameter, being dependent on both the C═C bond elongation and the Cu—(C═C) distance shortening. The CuI—(C═C) bond consists of two components. The [Cu(I)←L] σ donor–acceptor component – which is relatively insensitive to the olefinic bond orientation – is formed by the overlap of the occupied olefinic pπ orbital and the unoccupied 4s0 orbital of the CuI atom, and produces a shortening of the Cu—m distance (m is the mid-point of the C═C bond). The [Cu(I)→ L] π-dative component, based on electron transfer from the CuI 3d10 orbitals to the unoccupied antibonding orbital of the C═C group, which is strongly dependent on a proper olefinic group orientation in the metal coordination sphere, causes a lengthening of the C═ C bond. Therefore, both components increase the value of the C—Cu—C angle. Thus, shortening of the Cu—m distance and lengthening of the C═C bond, as well as an increase in the C—Cu—C angle, are the most informative values for estimating the effectiveness of the Cu—(C═C) interaction. An effective Cu—(C═C) interaction leads to a transformation of the copper coordination polyhedron from tetrahedral to trigonal-pyramidal, with the olefinic group in the basal plane and with concomitant lengthening of the central atom–axial ligand distance; this lengthening can proceed as far as the removal of the axial ligand from the metal coordination sphere, with the formation, as in the present structure, of a trigonal-planar copper environment.
The coordinated olefinic group, with a C═C distance of 1.344 (7) Å, is only slightly elongated as compared with the length of an uncoordinated C═ C bond. This value, as well as the C—Cu—C angle of 38.2 (2)° and a noteworthy 0.21 Å deviation of the olefinic C atoms from the Cl1/Cl2/m plane (corresponding to an 18° inclination of the C═C bond from the equatorial plane), reveal the low efficiency of the π interaction – that is, despite a rather effective σ-component [short Cu—m distance of 1.943 (6) Å], the π-dative component of the Cu—(C═C) interaction is less pronounced. Comparison of these values with the analogues in the structure of the copper(I) chloride π-complex with 1-allyl-4-aminopyridinium, where the Cu atom also possesses a trigonal-planar 2 C l + C═C environment [C—Cu—C = 38.0 (2)°, Cu—m = 1.950 (6) Å and C═C = 1.343 (6) Å], shows a similarly modest π interaction in both cases. The Cu—m distances are rather short for copper(I) π-complexes in general because of the absence of steric hindrance in the trigonal-planar metal environment, which includes two Cl atoms in addition to the C═C bond. The Cu1—C10(terminal) distance is, as usual, slightly shorter than the Cu1—C9 distance. All pyridine rings are strictly parallel to each other, but the shortest ring–ring distance (4.5 Å) indicates an absence of any aromatic π–π stacking. Infinite chains, formed by the CuLCl2 and CuCl4 subunits, are interconnected into a three-dimensional structure by weak N—H···Cl hydrogen bonds (Table 2 and Fig. 2). The H···Cl distances (2.75 and 2.83 Å) differ significantly from the values of 2.39–2.57 Å observed for the copper(I) chloride π-complex with 1-allyl-4-aminopyridinium, and 2.47–2.50 Å for the 1-allyl-2-aminopyridinium derivative. These π-complexes with N-allyl derivatives of aminopyridines, (2-H2N—C5H4NC3H5)2[Cu2Cl4] and (4-H2N—C5H4NC3H5)[CuCl2], possess structures with small inorganic fragments, Cu2Cl4 and CuCl2, respectively, and rather strong N—H···Cl hydrogen bonds. We note that the progression from the simplest metal-containing fragment, CuCl2−, in the complex with 1-allyl-4-aminopyridinium through Cu2Cl42− in the complex with 1-allyl-2-aminopyridinium to the complicated fragment (Cu4Cl6)n in the present compound with 1-allyl-3-aminopyridinium corresponds to decreasing order of pKa(base) values of the initial aminopyridines (9.25, 6.86 and 6.07, respectively). Thus, in (I), the electron-donor ability of the N atom of the NH2 group is weaker, which may be responsible for the elongated N—H···Cl contacts here as compared with the 2-amino- and 4-aminopyridinium analogues. Moreover, a `chelating' ligand arrangement [a 1-allyl-2-aminopyridinium cation bonded to the same Cu2Cl42− dimer via a Cu—(C═C) interaction and by N—H···Cl contacts] or a `bridging' organization (a 1-allyl-4-aminopyridinium moiety connected to one of the Cu atoms through the C═C-bond and to a chloro ligand of an adjacent metal atom through N—H···Cl hydrogen bonds) also promotes the formation of effective hydrogen bonds. In such cases, the H atom effectively completes the coordination about the Cl atom, hindering a bridging function for the halogen and thus effectively impeding the further association of small inorganic fragments into larger ones. In the case of the 1-allyl-3-aminopyridinium complex, (I), the weakly hydrogen-bonding amine H atoms cannot compete with the Cu atoms for a place in the chlorine environment, which in turn enables the formation of the infinite copper–chlorine chains.