(Acridine-N)trichlorogold(III)

The title compound, [AuCl₃(C₁₃H₉N)], is the first complex of gold and acridine to be reported. The coordination sphere of the Au atom is square planar. The crystal structure is built up of neutral complex mol­ecules linked into chains by means of attractive π–π interactions between the parallel acridine ligands.

S1. Comment

Single crystals of the title complex, (I), were prepared in order to obtain an insight into the vibrational spectra of the molecule and, subsequently, to compare these spectra of (I) with the SERS (surface-enhanced Raman scattering) spectra of the ligand adsorbed on colloidal gold (Jeong et al., 2000; Muniz-Miranda, 2000). This work is part of our project on the comparison of synthetic metal-ligand complexes (where the metal is Ag, Au, Pd or Pt and the ligand is an N-containing organic base) with analogous SERS systems (Srnova et al., 1997; Srnova et al., 1999). Having searched the Cambridge Structural Database (Allen & Kennard, 1993), we have found that (I) is the first complex of gold and acridine to be reported. \sch

The coordination of the Au atom is square planar, formed by the three Cl atoms and atom N1 of the acridine (acr) ligand (Fig. 1). The relevant distances and angles are summarized in Table 1.

The angle between the plane formed by the acr ligand and that given by the Au coordination sphere (Au/Cl1/Cl2/Cl3/N1) is 77.53 (8)°, which differs from the ideal value of 90°. This is due to π-π interactions between parallel acr ligands, which will be discussed below. If the angle were 90°, the Cl atoms of adjacent complex molecules would be too close to each other, and this would hinder the π-π interactions.

Neutral molecules of (I) are linked into chains running parallel to [100]. The linkage is realised by π-π interactions (Desiraju, 1995) between the planar acr ligands. As there is just one acr ligand per asymmetric unit and the space group P1 is generated by inversions and translations only, all the planes defined by the planar acr ligands are exactly parallel, i.e. the π-π interacting acr molecules are always parallel due to the space-group symmetry. Two types of π-π interaction found in the crystal structure of (I) are shown in Fig. 2. In type (i), the interaction between the acr at (x, y, z) and that generated by (-x, -y, -z) is, from the point of view of geometry, similar to the interaction found between the layers in graphite (Wyckoff, 1965). In type (ii), the interaction between the acr at (x, y, z) and that generated by (1 - x, -y, -z) is somewhat different, the molecules being mutually shifted, as shown in Fig. 2. In both cases, the interacting ligands exhibit a parallel-displaced geometry connected via a slightly attractive interaction (Hunter & Sanders, 1990; Hobza et al., 1994). The distances between the parallel planes are 3.460 (7) Å for interaction (i) and 3.620 (7) Å for interaction (ii).

Examination of the structure with PLATON (Spek, 1990) showed that there are no solvent-accessible voids in the crystal lattice. The structure of an analogous complex, with the same ligands as (I) and Cu as the central metal atom, has been reported by Healy et al. (1985).

Related literature

For related literature, see: Allen & Kennard (1993); Desiraju (1995); Healy et al. (1985); Hobza et al. (1994); Hunter & Sanders (1990); Jeong et al. (2000); Muniz-Miranda (2000); Spek (1990); Srnova et al. (1997, 1999); Wyckoff (1965).

S2. Experimental

Orange crystals of (I) were obtained by mixing equimolar amounts of HAuCl₄·3H₂O in water (0.04 M) and acridine in dioxane (0.04 M). Within 3 h, thin needle crystals appeared and these were filtered off. Prism crystals of (I), suitable for X-ray analysis, grew from the mother liquor in 2 d. No recrystallization was necessary.

S3. Refinement

Because of the presence of Au in (I), the proper absorption correction was the crucial step in the data reduction. Several types of absorption correction were tried. The best results were achieved with numerical absorption correction based on indexed crystal faces. H atoms were clearly visible in the difference electron-density map. They were set to calculated positions, with a C—H distance of 0.93 Å, and their isotropic displacement parameters were set equal to 1.2U_eq of the parent atom. The deepest hole in the final difference electron-density map was found 0.98 Å from Au.

Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: SCALEPACK (Otwinowski & Minor 1997); data reduction: DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1990); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The asymmetric unit of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The scheme of attractive π-π interactions between acridine ligands in (I).

(acridine-N)trichlorogold(III)

Crystal data

[AuCl3(C13H9N)]	Z = 2
Mr = 482.53	F(000) = 448
Triclinic, P1	Dx = 2.342 Mg m^−3
a = 7.6207 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.5869 (5) Å	Cell parameters from 3668 reflections
c = 10.6829 (5) Å	θ = 1–25°
α = 71.115 (3)°	µ = 11.32 mm^−1
β = 84.066 (3)°	T = 293 K
γ = 67.921 (2)°	Prism, dark orange
V = 684.16 (6) Å^3	0.21 × 0.11 × 0.06 mm

Data collection

Nonius KappaCCD diffractometer	2413 independent reflections
Radiation source: fine-focus sealed tube	2229 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
Detector resolution: 0.110 pixels mm^-1	θmax = 25.1°, θmin = 3.2°
ϕ and ω scans	h = 0→9
Absorption correction: gaussian (NUMERIC; Nonius, 1999)	k = −10→11
Tmin = 0.102, Tmax = 0.546	l = −12→12
5224 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.025	H-atom parameters constrained
wR(F^2) = 0.059	w = 1/[σ^2(Fo^2) + (0.0142P)^2 + 0.3962P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.034
2413 reflections	Δρmax = 0.99 e Å^−3
164 parameters	Δρmin = −1.20 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: heavy atom method	Extinction coefficient: 0.0058 (5)

Special details

Experimental. CCD (rotation scans, rotation per image 2°, 118 images collected using ϕ + ω scans, total scan length 168.0° ϕ and 48.0° ω, which corresponds to half the Ewald sphere)

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
Au1	0.13330 (2)	0.17696 (2)	0.321553 (17)	0.03418 (11)
Cl1	−0.14749 (19)	0.1400 (2)	0.34318 (15)	0.0495 (4)
Cl2	0.4124 (2)	0.2173 (2)	0.29449 (18)	0.0596 (4)
Cl3	0.0433 (2)	0.3144 (2)	0.46838 (15)	0.0547 (4)
N1	0.2101 (6)	0.0624 (5)	0.1804 (4)	0.0342 (10)
C2	0.1320 (7)	0.1434 (7)	0.0572 (5)	0.0374 (12)
C3	−0.0025 (8)	0.2998 (7)	0.0253 (6)	0.0455 (14)
H3	−0.0388	0.3503	0.0900	0.055*
C4	−0.0788 (9)	0.3768 (8)	−0.0981 (6)	0.0527 (15)
H4	−0.1692	0.4785	−0.1154	0.063*
C5	−0.0269 (10)	0.3091 (9)	−0.2008 (6)	0.0560 (17)
H5	−0.0803	0.3660	−0.2851	0.067*
C6	0.1004 (9)	0.1618 (9)	−0.1764 (6)	0.0545 (17)
H6	0.1345	0.1166	−0.2445	0.065*
C7	0.1859 (8)	0.0717 (8)	−0.0467 (5)	0.0426 (14)
C8	0.3142 (8)	−0.0827 (8)	−0.0161 (7)	0.0516 (17)
H8	0.3495	−0.1320	−0.0815	0.062*
C9	0.3903 (7)	−0.1642 (7)	0.1101 (6)	0.0444 (14)
C10	0.5196 (9)	−0.3253 (10)	0.1466 (9)	0.068 (2)
H10	0.5558	−0.3771	0.0828	0.082*
C11	0.5902 (10)	−0.4037 (10)	0.2709 (10)	0.078 (2)
H11	0.6733	−0.5085	0.2927	0.094*
C12	0.5364 (9)	−0.3245 (9)	0.3683 (8)	0.0652 (19)
H12	0.5875	−0.3786	0.4535	0.078*
C13	0.4136 (8)	−0.1733 (8)	0.3415 (7)	0.0522 (15)
H13	0.3805	−0.1249	0.4076	0.063*
C14	0.3346 (7)	−0.0880 (7)	0.2100 (6)	0.0425 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Au1	0.03475 (14)	0.03952 (16)	0.03130 (15)	−0.01086 (10)	0.00090 (8)	−0.01804 (10)
Cl1	0.0390 (7)	0.0617 (10)	0.0558 (9)	−0.0212 (7)	0.0093 (6)	−0.0276 (8)
Cl2	0.0418 (8)	0.0830 (13)	0.0727 (11)	−0.0299 (8)	0.0064 (7)	−0.0410 (10)
Cl3	0.0692 (9)	0.0593 (10)	0.0428 (8)	−0.0181 (8)	0.0050 (7)	−0.0323 (8)
N1	0.033 (2)	0.037 (3)	0.035 (2)	−0.0135 (19)	0.0044 (18)	−0.014 (2)
C2	0.045 (3)	0.046 (3)	0.034 (3)	−0.025 (3)	0.009 (2)	−0.021 (3)
C3	0.056 (3)	0.050 (4)	0.039 (3)	−0.023 (3)	0.005 (3)	−0.022 (3)
C4	0.065 (4)	0.055 (4)	0.042 (3)	−0.027 (3)	−0.006 (3)	−0.012 (3)
C5	0.076 (4)	0.072 (5)	0.033 (3)	−0.046 (4)	−0.004 (3)	−0.010 (3)
C6	0.073 (4)	0.078 (5)	0.037 (3)	−0.046 (4)	0.013 (3)	−0.031 (4)
C7	0.052 (3)	0.061 (4)	0.036 (3)	−0.035 (3)	0.014 (2)	−0.030 (3)
C8	0.054 (3)	0.068 (5)	0.060 (4)	−0.035 (3)	0.027 (3)	−0.049 (4)
C9	0.037 (3)	0.045 (4)	0.065 (4)	−0.019 (3)	0.016 (3)	−0.037 (3)
C10	0.044 (4)	0.063 (5)	0.111 (7)	−0.014 (3)	0.009 (4)	−0.051 (5)
C11	0.049 (4)	0.057 (5)	0.130 (8)	−0.008 (4)	0.001 (4)	−0.044 (5)
C12	0.048 (4)	0.051 (4)	0.085 (5)	−0.004 (3)	−0.011 (3)	−0.019 (4)
C13	0.049 (3)	0.047 (4)	0.059 (4)	−0.012 (3)	0.000 (3)	−0.019 (3)
C14	0.034 (3)	0.044 (4)	0.059 (4)	−0.017 (3)	0.010 (3)	−0.027 (3)

Geometric parameters (Å, º)

Au1—N1	2.056 (4)	C6—H6	0.9300
Au1—Cl3	2.2588 (13)	C7—C8	1.385 (9)
Au1—Cl1	2.2745 (13)	C8—C9	1.380 (9)
Au1—Cl2	2.2751 (14)	C8—H8	0.9300
N1—C14	1.348 (7)	C9—C14	1.425 (8)
N1—C2	1.358 (7)	C9—C10	1.433 (10)
C2—C3	1.415 (8)	C10—C11	1.347 (11)
C2—C7	1.436 (7)	C10—H10	0.9300
C3—C4	1.351 (8)	C11—C12	1.420 (10)
C3—H3	0.9300	C11—H11	0.9300
C4—C5	1.400 (8)	C12—C13	1.351 (9)
C4—H4	0.9300	C12—H12	0.9300
C5—C6	1.337 (9)	C13—C14	1.437 (9)
C5—H5	0.9300	C13—H13	0.9300
C6—C7	1.442 (8)
N1—Au1—Cl3	177.13 (13)	C8—C7—C2	118.1 (5)
N1—Au1—Cl1	89.61 (12)	C8—C7—C6	123.3 (5)
Cl3—Au1—Cl1	90.57 (5)	C2—C7—C6	118.6 (6)
N1—Au1—Cl2	89.64 (12)	C9—C8—C7	121.0 (5)
Cl3—Au1—Cl2	90.12 (6)	C9—C8—H8	119.5
Cl1—Au1—Cl2	178.57 (6)	C7—C8—H8	119.5
C14—N1—C2	121.5 (4)	C8—C9—C14	119.2 (5)
C14—N1—Au1	120.7 (4)	C8—C9—C10	122.7 (6)
C2—N1—Au1	117.8 (3)	C14—C9—C10	118.1 (6)
N1—C2—C3	122.2 (4)	C11—C10—C9	121.8 (7)
N1—C2—C7	120.3 (5)	C11—C10—H10	119.1
C3—C2—C7	117.5 (5)	C9—C10—H10	119.1
C4—C3—C2	120.8 (5)	C10—C11—C12	119.2 (7)
C4—C3—H3	119.6	C10—C11—H11	120.4
C2—C3—H3	119.6	C12—C11—H11	120.4
C3—C4—C5	122.5 (6)	C13—C12—C11	122.3 (7)
C3—C4—H4	118.8	C13—C12—H12	118.9
C5—C4—H4	118.8	C11—C12—H12	118.9
C6—C5—C4	119.3 (6)	C12—C13—C14	119.4 (6)
C6—C5—H5	120.4	C12—C13—H13	120.3
C4—C5—H5	120.4	C14—C13—H13	120.3
C5—C6—C7	121.4 (5)	N1—C14—C9	120.0 (6)
C5—C6—H6	119.3	N1—C14—C13	120.9 (5)
C7—C6—H6	119.3	C9—C14—C13	119.1 (5)
Cl1—Au1—N1—C14	−103.5 (4)	C2—C7—C8—C9	−1.0 (8)
Cl2—Au1—N1—C14	77.8 (4)	C6—C7—C8—C9	−179.3 (5)
Cl1—Au1—N1—C2	76.8 (4)	C7—C8—C9—C14	0.3 (8)
Cl2—Au1—N1—C2	−102.0 (4)	C7—C8—C9—C10	178.4 (5)
C14—N1—C2—C3	178.3 (5)	C8—C9—C10—C11	−179.0 (6)
Au1—N1—C2—C3	−1.9 (6)	C14—C9—C10—C11	−0.9 (9)
C14—N1—C2—C7	−2.2 (7)	C9—C10—C11—C12	−0.5 (11)
Au1—N1—C2—C7	177.6 (3)	C10—C11—C12—C13	1.2 (11)
N1—C2—C3—C4	−179.4 (5)	C11—C12—C13—C14	−0.4 (10)
C7—C2—C3—C4	1.0 (8)	C2—N1—C14—C9	1.5 (7)
C2—C3—C4—C5	−1.6 (9)	Au1—N1—C14—C9	−178.3 (4)
C3—C4—C5—C6	1.2 (9)	C2—N1—C14—C13	−178.9 (5)
C4—C5—C6—C7	−0.3 (9)	Au1—N1—C14—C13	1.4 (7)
N1—C2—C7—C8	1.9 (7)	C8—C9—C14—N1	−0.5 (8)
C3—C2—C7—C8	−178.5 (5)	C10—C9—C14—N1	−178.6 (5)
N1—C2—C7—C6	−179.7 (5)	C8—C9—C14—C13	179.8 (5)
C3—C2—C7—C6	−0.2 (7)	C10—C9—C14—C13	1.7 (8)
C5—C6—C7—C8	178.1 (6)	C12—C13—C14—N1	179.3 (6)
C5—C6—C7—C2	−0.2 (8)	C12—C13—C14—C9	−1.1 (9)