Bis­(benzene­thiol­ato-S)(2,9-di­methyl-1,10-phenanthroline-N,N′)­cadmium(II)

The title compound, [Cd(C₆H₅S)₂(C₁₄H₁₂N₂)], exists as monomeric mol­ecules with offset π-stacking interactions between the phenanthroline ligands in adjacent mol­ecules.

S1. Comment

Highly colored and luminescent complexes can be formed when Zn^II or Cd^II is coordinated in a heteroleptic field containing N,N-heterocyclic and either one dithiolate or two monothiolate ligands. This visible transition has been described as a metal-mediated π–π* ligand-to-ligand charge-transfer (LLCT) transition (Koester, 1975; Crosby et al., 1985; Truesdell & Crosby, 1985; Kutal, 1990; Burt & Crosby, 1994) and is observed for a large variety of mono- and dithiolate plus N,N-heterocyclic ligand sets (Muresan & Muresan, 1979; Fernadez & Kisch, 1984; Crosby et al., 1985; Highland & Crosby, 1985; Highland et al., 1986; Reddy et al., 1992; Galin et al., 1993; Gronlund, Burt & Wacholtz, 1995; Gronlund, Wacholtz & Mague, 1995; Halvorsen et al., 1995; Zemskova et al., 1998; Yam et al., 1999; Wang et al., 2000). A number of recent studies have indicated that unusual multinuclear Zn^II and Cd^II complexes are obtained when the mixed ligand set is a planar N,N-heterocyclic ligand in combination with a dithiolate ligand (Halvorsen et al., 1995; Gronlund, Wacholtz & Mague, 1995; Wang et al., 2000; Lowther et al., 2001). However, when substituents are attached to the periphery of 1,10-phenanthroline ligands, only mononuclear complexes tend to be observed. In one Zn^II system, two different crystal forms are obtained for very subtle conformational changes in the monthiolate ligands (Jordan et al., 1991). In order to fully investigate the structure–property relationships in analogous Cd^II complexes for comparison with these Zn^II systems, we have investigated the reactions of monothiolate complexes of Cd^II with substituted 1,10-phenanthroline ligands.

Bis(benzenthiolato)(2,9-dimethyl-1,10-phenanthroline)cadmium(II), (I), is monomeric in contrast to related 1,2-benzenedithiolate complexes which are dinuclear (Lowther et al., 2001; Gronlund, Wacholtz & Mague, 1995). The elongated displacement ellipsoid for S2 is evidence for positional disorder in this atom, but attempts to model this by two or even three partially occupied sites were unsuccessful. It was evident from these attempts that no simple disorder model would be sufficient to describe alternate positions for this atom. It appears from Fig. 3 that the whole molecule is disordered over several slightly different conformations involving libration about a point near the center of the chelate ring. This is effectively an `inversion' about this point and evidently the several conformations existing over the whole of the crystal vary considerably more in the locations of S2 and its attached phenyl ring than in the locations of the remaining atoms. This is likely the reason for the Cd—S distances, particularly Cd—S2, appearing shorter than the usual values of around 2.50 Å. The two phenyl rings are inclined at an angle of 56.2 (1)° (Fig. 1). That built on C7 is nearly parallel to the mean plane of the phenanthroline ligand [dihedral angle is 9.1 (2)°], while the other makes an angle of 64.3 (2)° with this mean plane. Fig. 2 depicts the offset π-stacking between phenanthroline ligands on neighboring molecules. The rings in question are virtually parallel, with a distance between the centers of gravity of the two rings of 3.62 (1) Å and a perpendicular distance from the center of gravity of one ring to the mean plane of the other of 3.55 (1) Å.

Related literature

For related literature, see: Burt & Crosby (1994); Crosby et al. (1985); Fernadez & Kisch (1984); Galin et al. (1993); Gronlund, Burt & Wacholtz (1995); Gronlund, Wacholtz & Mague (1995); Halvorsen et al. (1995); Highland & Crosby (1985); Highland et al. (1986); Jordan et al. (1991); Koester (1975); Kutal (1990); Lowther et al. (2001); Muresan & Muresan (1979); Reddy et al. (1992); Truesdell & Crosby (1985); Wang et al. (2000); Yam et al. (1999); Zemskova et al. (1998).

S2. Experimental

Benzenethiol (0.21 ml, 2.1 mmol) in hot ethanol (10 ml) was added dropwise to a hot solution of cadmium acetate dihydrate (266.5 mg, 1.0 mmol) in a 1:1 (v/v) mixture (50 ml) of ethanol and dimethylformamide. The solution was brought to reflux and 2,9-dimethyl-1,10-phenanthroline monohydrate (226.3 mg, 1.0 mmol) dissolved in hot ethanol (25 ml) was added slowly with stirring. A flocculent golden yellow precipitate formed immediately and the reaction was continued for an additional 30 min. The mixture was cooled to room temperature, allowed to stand for 24 h and the solid collected by suction filtration (yield 94%). Yellow crystals were obtained by slow evaporation of a dimethylformamide solution of the complex in air. Analysis calculated for C₂₆H₂₂CdN₂S₂: C 57.93, H 4.12, N 5.20%; found: C 57.9, H 4.1, N 5.2.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. Perspective view of (I). Displacement ellipsoids are drawn at the 40% probability level and H atoms have been omitted for clarity.
	Fig. 2. View of the π-stacking interaction in (I). The molecule containing primed atoms is related to the other by the operation 1/2 - x, 1/2 + y, z.
	Fig. 3. View of (I) perpendicular to the plane of the phenanthroline ligand, showing the apparent librational motion.

Bis(benzenethiolato)(2,9-dimethyl-1,10-phenanthroline)cadmium(II)

Crystal data

[Cd(C6H5S)2(C14H12N2)]	Dx = 1.519 Mg m^−3
Mr = 538.98	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 25 reflections
a = 14.164 (2) Å	θ = 11.1–15.8°
b = 12.034 (2) Å	µ = 1.12 mm^−1
c = 27.648 (3) Å	T = 293 K
V = 4712.5 (13) Å^3	Column, pale orange
Z = 8	0.48 × 0.28 × 0.16 mm
F(000) = 2176

Data collection

Enraf-Nonius CAD-4 diffractometer	2388 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.000
Graphite monochromator	θmax = 26.0°, θmin = 1.5°
θ/2θ scans	h = 0→17
Absorption correction: empirical (using intensity measurements) via ψ scans (North et al., 1968)	k = 0→14
Tmin = 0.734, Tmax = 0.836	l = 0→34
4548 measured reflections	2 standard reflections every 120 min
4548 independent reflections	intensity decay: <1%

Refinement

Refinement on F^2	Primary atom site location: heavy-atom method
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.102	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0374P)^2 + 2.712P] where P = (Fo^2 + 2Fc^2)/3
4548 reflections	(Δ/σ)max = 0.002
282 parameters	Δρmax = 0.45 e Å^−3
0 restraints	Δρmin = −0.51 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. The thiolate ligand containing S2 and C7 - C12 appears to be affected positional disorder as evidenced by the larger thermal ellipsoids of these atoms as compared with those of the other thiolate group but no resolved alternate positions could be detected.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cd	0.02908 (2)	0.65037 (3)	0.127156 (12)	0.05439 (13)
S1	−0.03350 (9)	0.77347 (12)	0.06519 (5)	0.0678 (4)
S2	−0.02762 (11)	0.5356 (2)	0.19284 (7)	0.1259 (8)
N1	0.1675 (2)	0.7350 (3)	0.15505 (12)	0.0476 (9)
N2	0.1584 (2)	0.5521 (3)	0.09622 (12)	0.0440 (8)
C1	−0.1571 (3)	0.7530 (4)	0.06074 (15)	0.0486 (11)
C2	−0.2098 (4)	0.8344 (4)	0.03723 (18)	0.0624 (13)
H2	−0.1800	0.8977	0.0254	0.075*
C3	−0.3059 (4)	0.8217 (5)	0.0314 (2)	0.0740 (17)
H3	−0.3403	0.8767	0.0157	0.089*
C4	−0.3516 (3)	0.7285 (5)	0.04843 (19)	0.0693 (15)
H4	−0.4163	0.7201	0.0440	0.083*
C5	−0.3007 (3)	0.6486 (5)	0.07191 (17)	0.0641 (14)
H5	−0.3312	0.5863	0.0842	0.077*
C6	−0.2033 (3)	0.6600 (4)	0.07758 (16)	0.0566 (12)
H6	−0.1692	0.6041	0.0929	0.068*
C7	−0.1524 (3)	0.5358 (5)	0.19129 (17)	0.0561 (13)
C8	−0.2026 (5)	0.4456 (5)	0.17232 (19)	0.0800 (18)
H8	−0.1707	0.3864	0.1582	0.096*
C9	−0.3019 (5)	0.4457 (6)	0.1748 (2)	0.0838 (19)
H9	−0.3358	0.3864	0.1621	0.101*
C10	−0.3477 (4)	0.5310 (6)	0.1955 (2)	0.0829 (18)
H10	−0.4133	0.5300	0.1975	0.099*
C11	−0.2995 (4)	0.6171 (6)	0.2131 (2)	0.0808 (17)
H11	−0.3319	0.6767	0.2266	0.097*
C12	−0.2036 (4)	0.6188 (4)	0.21158 (19)	0.0654 (14)
H12	−0.1719	0.6792	0.2249	0.078*
C13	0.1521 (4)	0.4628 (4)	0.06824 (16)	0.0557 (12)
C14	0.2338 (4)	0.4076 (4)	0.05177 (19)	0.0684 (15)
H14	0.2284	0.3439	0.0329	0.082*
C15	0.3195 (4)	0.4473 (5)	0.0634 (2)	0.0730 (16)
H15	0.3732	0.4121	0.0515	0.088*
C16	0.3292 (3)	0.5409 (4)	0.09308 (17)	0.0567 (13)
C17	0.4180 (3)	0.5863 (5)	0.1080 (2)	0.0802 (17)
H17	0.4737	0.5526	0.0980	0.096*
C18	0.4217 (3)	0.6768 (5)	0.1362 (2)	0.0780 (18)
H18	0.4803	0.7058	0.1446	0.094*
C19	0.3383 (3)	0.7297 (4)	0.15358 (19)	0.0588 (13)
C20	0.3386 (4)	0.8232 (5)	0.1830 (2)	0.0772 (18)
H20	0.3958	0.8536	0.1929	0.093*
C21	0.2578 (5)	0.8700 (4)	0.19740 (19)	0.0770 (17)
H21	0.2590	0.9334	0.2166	0.092*
C22	0.1706 (4)	0.8234 (4)	0.18342 (17)	0.0622 (14)
C23	0.2498 (3)	0.6878 (4)	0.13979 (14)	0.0438 (10)
C24	0.2449 (3)	0.5912 (4)	0.10890 (14)	0.0427 (10)
C25	0.0784 (5)	0.8713 (5)	0.1994 (2)	0.093 (2)
H25A	0.0377	0.8798	0.1719	0.112*
H25B	0.0889	0.9424	0.2141	0.112*
H25C	0.0494	0.8223	0.2224	0.112*
C26	0.0562 (4)	0.4218 (5)	0.0552 (2)	0.0797 (17)
H26A	0.0315	0.3778	0.0813	0.096*
H26B	0.0600	0.3773	0.0265	0.096*
H26C	0.0152	0.4840	0.0495	0.096*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd	0.03470 (16)	0.0740 (2)	0.0544 (2)	0.00191 (19)	0.00270 (16)	0.0072 (2)
S1	0.0483 (6)	0.0805 (9)	0.0747 (9)	−0.0160 (7)	−0.0090 (7)	0.0220 (7)
S2	0.0464 (8)	0.202 (2)	0.1290 (14)	0.0240 (12)	0.0211 (9)	0.1062 (15)
N1	0.050 (2)	0.051 (2)	0.042 (2)	0.0030 (19)	−0.0048 (17)	−0.0001 (19)
N2	0.045 (2)	0.046 (2)	0.041 (2)	−0.0003 (18)	−0.0008 (15)	0.0008 (18)
C1	0.050 (3)	0.054 (3)	0.042 (3)	0.001 (2)	−0.004 (2)	0.000 (2)
C2	0.067 (3)	0.053 (3)	0.068 (3)	0.007 (3)	−0.003 (3)	0.011 (3)
C3	0.063 (3)	0.081 (4)	0.078 (4)	0.032 (3)	−0.015 (3)	0.011 (3)
C4	0.039 (3)	0.101 (4)	0.068 (3)	0.012 (3)	−0.005 (2)	0.004 (3)
C5	0.050 (3)	0.082 (4)	0.060 (3)	−0.008 (3)	−0.001 (2)	0.005 (3)
C6	0.049 (3)	0.065 (3)	0.055 (3)	0.003 (3)	−0.004 (2)	0.013 (3)
C7	0.044 (3)	0.070 (3)	0.055 (3)	0.003 (3)	0.009 (2)	0.020 (3)
C8	0.120 (5)	0.063 (4)	0.057 (3)	0.026 (4)	0.024 (3)	0.011 (3)
C9	0.102 (5)	0.081 (5)	0.069 (4)	−0.042 (4)	−0.019 (4)	0.008 (4)
C10	0.051 (3)	0.112 (5)	0.085 (4)	−0.007 (4)	0.002 (3)	0.019 (4)
C11	0.066 (4)	0.090 (5)	0.087 (4)	0.018 (4)	0.011 (3)	0.000 (4)
C12	0.065 (3)	0.062 (3)	0.069 (4)	−0.001 (3)	0.002 (3)	−0.004 (3)
C13	0.073 (3)	0.050 (3)	0.044 (3)	−0.002 (3)	−0.001 (2)	0.008 (2)
C14	0.094 (5)	0.054 (3)	0.058 (3)	0.015 (3)	0.008 (3)	−0.007 (3)
C15	0.073 (4)	0.079 (4)	0.067 (4)	0.030 (3)	0.018 (3)	0.006 (3)
C16	0.046 (3)	0.069 (3)	0.056 (3)	0.011 (3)	0.011 (2)	0.016 (3)
C17	0.036 (3)	0.100 (5)	0.105 (5)	0.016 (3)	0.010 (3)	0.026 (4)
C18	0.034 (3)	0.096 (5)	0.104 (5)	−0.008 (3)	−0.007 (3)	0.026 (4)
C19	0.048 (3)	0.065 (3)	0.064 (3)	−0.015 (3)	−0.011 (2)	0.015 (3)
C20	0.075 (4)	0.079 (4)	0.078 (4)	−0.028 (3)	−0.026 (3)	0.017 (3)
C21	0.113 (5)	0.061 (4)	0.057 (3)	−0.013 (4)	−0.023 (3)	−0.007 (3)
C22	0.081 (4)	0.058 (3)	0.048 (3)	0.010 (3)	−0.013 (3)	−0.002 (3)
C23	0.040 (2)	0.045 (3)	0.046 (2)	−0.0017 (19)	−0.0017 (19)	0.011 (2)
C24	0.037 (2)	0.048 (3)	0.044 (2)	0.0011 (19)	0.003 (2)	0.009 (2)
C25	0.119 (5)	0.089 (4)	0.071 (4)	0.043 (4)	−0.003 (4)	−0.025 (3)
C26	0.098 (5)	0.070 (4)	0.071 (4)	−0.024 (3)	−0.016 (3)	−0.008 (3)

Geometric parameters (Å, º)

Cd—N1	2.341 (4)	C8—C9	1.408 (8)
Cd—N2	2.341 (3)	C9—C10	1.342 (8)
Cd—S2	2.4189 (16)	C10—C11	1.333 (8)
Cd—S1	2.4321 (14)	C11—C12	1.359 (7)
S1—C1	1.772 (4)	C13—C14	1.410 (7)
S2—C7	1.768 (5)	C13—C26	1.490 (7)
N1—C22	1.322 (6)	C14—C15	1.343 (7)
N1—C23	1.363 (5)	C15—C16	1.401 (7)
N2—C13	1.328 (6)	C16—C24	1.408 (6)
N2—C24	1.359 (5)	C16—C17	1.432 (7)
C1—C6	1.377 (6)	C17—C18	1.339 (8)
C1—C2	1.393 (6)	C18—C19	1.427 (7)
C2—C3	1.379 (7)	C19—C20	1.389 (7)
C3—C4	1.377 (7)	C19—C23	1.403 (6)
C4—C5	1.365 (7)	C20—C21	1.336 (8)
C5—C6	1.395 (6)	C21—C22	1.410 (7)
C7—C12	1.356 (7)	C22—C25	1.494 (7)
C7—C8	1.399 (8)	C23—C24	1.444 (6)
N1—Cd—N2	71.64 (12)	C11—C10—C9	120.1 (6)
N1—Cd—S2	106.22 (10)	C10—C11—C12	120.8 (6)
N2—Cd—S2	104.21 (10)	C7—C12—C11	122.4 (6)
N1—Cd—S1	105.80 (9)	N2—C13—C14	121.0 (5)
N2—Cd—S1	109.59 (9)	N2—C13—C26	118.0 (5)
S2—Cd—S1	139.08 (5)	C14—C13—C26	121.0 (5)
C1—S1—Cd	108.91 (15)	C15—C14—C13	119.8 (5)
C7—S2—Cd	108.23 (16)	C14—C15—C16	121.0 (5)
C22—N1—C23	119.4 (4)	C15—C16—C24	116.4 (4)
C22—N1—Cd	125.0 (3)	C15—C16—C17	124.2 (5)
C23—N1—Cd	115.6 (3)	C24—C16—C17	119.4 (5)
C13—N2—C24	119.4 (4)	C18—C17—C16	120.8 (5)
C13—N2—Cd	124.7 (3)	C17—C18—C19	121.7 (5)
C24—N2—Cd	115.9 (3)	C20—C19—C23	117.0 (5)
C6—C1—C2	118.3 (4)	C20—C19—C18	123.8 (5)
C6—C1—S1	124.0 (3)	C23—C19—C18	119.2 (5)
C2—C1—S1	117.6 (4)	C21—C20—C19	120.8 (5)
C3—C2—C1	120.3 (5)	C20—C21—C22	120.1 (5)
C4—C3—C2	120.9 (5)	N1—C22—C21	120.8 (5)
C5—C4—C3	119.2 (5)	N1—C22—C25	117.1 (5)
C4—C5—C6	120.4 (5)	C21—C22—C25	122.1 (5)
C1—C6—C5	120.8 (4)	N1—C23—C19	121.9 (4)
C12—C7—C8	117.1 (5)	N1—C23—C24	118.5 (4)
C12—C7—S2	121.7 (4)	C19—C23—C24	119.5 (4)
C8—C7—S2	121.0 (5)	N2—C24—C16	122.4 (4)
C7—C8—C9	119.2 (5)	N2—C24—C23	118.3 (4)
C10—C9—C8	120.4 (6)	C16—C24—C23	119.3 (4)