metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

(2,9-Di­methyl-1,10-phenanthroline-κ2N,N′)di­iodidocadmium

aDepartment of Chemistry, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia, bPetrochemical Research Chair, College of Science, King Saud, University, Riyadh, Saudi Arabia, and cLaboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna Bizerte, Tunisia
*Correspondence e-mail: mohamedrzaigui@yahoo.fr

(Received 5 October 2011; accepted 25 October 2011; online 2 November 2011)

In the title compound, [CdI2(C14H12N2)], the mol­ecule sits on a crystallographic twofold axis. The coordination sphere of the CdII atom is built of two symmetry-equivalent N atoms of one 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand and two symmetry-equivalent I atoms, thus forming a distorted tetra­hedral geometry. Inversion-related mol­ecules inter­act along the c-axis direction by ππ stacking inter­actions between the phenanthroline ring systems, with centroid–centroid distances of 3.707 (9) and 3.597 (10) Å.

Related literature

For coordination chemistry of phenanthroline derivatives and their applications, see: Miller et al. (1999[Miller, M. T., Gantzel, P. K. & Karpishin, T. B. (1999). J. Am. Chem. Soc. 121, 4292-4293.]); Bodoki et al. (2009[Bodoki, A., Hangan, A., Oprean, L., Alzuet, G., Castineiras, A. & Borras, J. (2009). Polyhedron, 28, 2537-2544.]); Kane-Maguire & Wheeler (2001[Kane-Maguire, N. A. P. & Wheeler, J. F. (2001). Coord. Chem. Rev. 211, 145-162.]); Shahabadi et al. (2009[Shahabadi, N., Kashanian, S. & Purfoulad, M. (2009). Spectrochim. Acta Part A, 72, 757-761.]). For related structures involving 2,9-dimethyl-1,10-phenanthroline, see: Alizadeh et al. (2009[Alizadeh, R., Heidari, A., Ahmadi, R. & Amani, V. (2009). Acta Cryst. E65, m483-m484.]); Preston & Kennard (1969[Preston, H. S. & Kennard, C. H. L. (1969). J. Chem. Soc. A, pp. 1956-1961.]); Wang & Zhong (2009[Wang, B. S. & Zhong, H. (2009). Acta Cryst. E65, m1156.]). For background information on ππ stacking inter­actions, see: Janiak (2000[Janiak, C. (2000). J. Chem. Soc. Dalton Trans. pp. 3885-3896.]).

[Scheme 1]

Experimental

Crystal data
  • [CdI2(C14H12N2)]

  • Mr = 574.46

  • Monoclinic, C 2/c

  • a = 15.690 (3) Å

  • b = 11.580 (2) Å

  • c = 9.836 (5) Å

  • β = 114.65 (4)°

  • V = 1624.3 (9) Å3

  • Z = 4

  • Ag Kα radiation

  • λ = 0.56087 Å

  • μ = 2.72 mm−1

  • T = 293 K

  • 0.35 × 0.23 × 0.19 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: multi-scan (SORTAV; Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]) Tmin = 0.563, Tmax = 0.605

  • 6126 measured reflections

  • 3986 independent reflections

  • 2306 reflections with I > 2σ(I)

  • Rint = 0.020

  • 2 standard reflections every 120 min intensity decay: none

Refinement
  • R[F2 > 2σ(F2)] = 0.047

  • wR(F2) = 0.127

  • S = 1.02

  • 3986 reflections

  • 88 parameters

  • H-atom parameters constrained

  • Δρmax = 1.65 e Å−3

  • Δρmin = −1.30 e Å−3

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994[Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); program(s) used to solve structure: SIR92 (Altomare et al., 1994[Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEPIII (Burnett & Johnson, 1996[Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.]) and DIAMOND (Brandenburg & Putz, 2005[Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

Metal complexes using 1,10-phenanthroline (phen) and their modified derivative ligands are particularly attractive species for design and developing novel diagnostic and therapeutic agents that can recognize and selectively cleave DNA (Miller et al., 1999; Bodoki et al., 2009). The ligands or the metal in these complexes can be varied in an easily controlled manner to facilitate an individual application, thus providing an easy access for the understanding of details involved in DNA-binding and cleavage (Kane-Maguire & Wheeler, 2001; Shahabadi et al., 2009). We report herein the synthesis and crystal structure of a new CdII complex, [CdI2(dmphen)] (I) where dmphen = (2,9-dimethyl-1,10-phenanthroline).

The molecular structure of (I) is shown in Fig. 1. The CdII cation is located on a special position (1/2, y, 1/4) in a tetrahedral environment built up from two nitrogen atoms (N1, N1i) of one dmphen bidentate ligand and two iodide ions (I1, I1i), [(i): 1 - x, y, 1/2 - z].

Geometrical analysis of the bond lengths and angles around the cadmium atom, Cd–N = 2.305 (3) Å, Cd–I = 2.691 (1)Å and I–Cd–Ii = 129.82 (4)°, N–Cd–Ni = 73.O5(16)°, N–Cd–I = 112.40 (8)° and N—Cd—Ii = 107.48 (8)°, [(i): 1 - x, y, 1/2 - z], shows that the CdI2N2 is distorted. The shortest Cd···Cd distance is 6.650 (2) Å. Similar coordination geometry around the central atom has been observed in other transition metal complexes such as [HgBr2(dmphen)], (Alizadeh et al., 2009), [ZnCl2(dmphen)], (Preston & Kennard, 1969), [CuCl2(dmphen)] (Wang et al., 2009). The phenyl and pyridyl rings of dmphen ligand are planar with a mean atomic deviation of 0.011 Å and 0.013 Å respectively. The C–C bonds of the two methyl groups are positioned close to the benzene ring plane since the C7–C1–N1–C5 and C7–C1–C2–C3 torsion angles are -179.3 (4)° and -179.5 (5)° respectively.

In the crystal packing the complex molecules are linked together by intermolecular ππ stacking interactions between the pyridyl N1C5C4C3C2C1 (of centroid Cg1) and phenyl C5C4C6C6iC4iC5i [symmetry code: (i) 1 - x, y, 1/2 - z] (of centroid Cg2) rings. The centroid–centroid distances between Cg1···Cg2ii and Cg2···Cg2ii [symmetry code: (ii) 1 - x, -y, 1 - z] are 3.707 (9) and 3.597 (10)Å respectively, which is less than the 3.8 Å maximum value regarded as relevant for ππ interactions (Janiak, 2000).

Related literature top

For coordination chemistry of phenanthroline derivatives and their applications, see: Miller et al. (1999); Bodoki et al. (2009); Kane-Maguire & Wheeler (2001); Shahabadi et al. (2009). For related structures involving 2,9-dimethyl-1,10-phenanthroline, see: Alizadeh et al. (2009); Preston & Kennard (1969); Wang & Zhong (2009). For background information on ππ stacking interactions, see: Janiak (2000).

Experimental top

A mixture of 2,9-Dimethyl-1,10-phenanthroline (50.0 mg, 0.24 mmol) in dichloromethane (5 ml) and CdI2 (87.9 mg, 0.24 mmol) in methanol (10 ml) was placed in a round bottom flask and stirred for 4 h at room temperature. The solution was concentrated to about 1 ml under reduced pressure. Addition of 40 ml of n-hexane caused the precipitation of white powder, which was filtered and then dried under vacuum to 108 mg (yield 94% based on Cd). The crystal was grown by slow diffusion of diethyl ether into a solution of the complex in dichloromethane.

Refinement top

All H atoms attached to C atoms were fixed geometrically and treated as riding, with C—H = 0.93 Å and 0.96 Å and with Uiso(H) = 1.2Ueq(C) and Uiso(H) = 1.5Ueq(Cmethyl).

Structure description top

Metal complexes using 1,10-phenanthroline (phen) and their modified derivative ligands are particularly attractive species for design and developing novel diagnostic and therapeutic agents that can recognize and selectively cleave DNA (Miller et al., 1999; Bodoki et al., 2009). The ligands or the metal in these complexes can be varied in an easily controlled manner to facilitate an individual application, thus providing an easy access for the understanding of details involved in DNA-binding and cleavage (Kane-Maguire & Wheeler, 2001; Shahabadi et al., 2009). We report herein the synthesis and crystal structure of a new CdII complex, [CdI2(dmphen)] (I) where dmphen = (2,9-dimethyl-1,10-phenanthroline).

The molecular structure of (I) is shown in Fig. 1. The CdII cation is located on a special position (1/2, y, 1/4) in a tetrahedral environment built up from two nitrogen atoms (N1, N1i) of one dmphen bidentate ligand and two iodide ions (I1, I1i), [(i): 1 - x, y, 1/2 - z].

Geometrical analysis of the bond lengths and angles around the cadmium atom, Cd–N = 2.305 (3) Å, Cd–I = 2.691 (1)Å and I–Cd–Ii = 129.82 (4)°, N–Cd–Ni = 73.O5(16)°, N–Cd–I = 112.40 (8)° and N—Cd—Ii = 107.48 (8)°, [(i): 1 - x, y, 1/2 - z], shows that the CdI2N2 is distorted. The shortest Cd···Cd distance is 6.650 (2) Å. Similar coordination geometry around the central atom has been observed in other transition metal complexes such as [HgBr2(dmphen)], (Alizadeh et al., 2009), [ZnCl2(dmphen)], (Preston & Kennard, 1969), [CuCl2(dmphen)] (Wang et al., 2009). The phenyl and pyridyl rings of dmphen ligand are planar with a mean atomic deviation of 0.011 Å and 0.013 Å respectively. The C–C bonds of the two methyl groups are positioned close to the benzene ring plane since the C7–C1–N1–C5 and C7–C1–C2–C3 torsion angles are -179.3 (4)° and -179.5 (5)° respectively.

In the crystal packing the complex molecules are linked together by intermolecular ππ stacking interactions between the pyridyl N1C5C4C3C2C1 (of centroid Cg1) and phenyl C5C4C6C6iC4iC5i [symmetry code: (i) 1 - x, y, 1/2 - z] (of centroid Cg2) rings. The centroid–centroid distances between Cg1···Cg2ii and Cg2···Cg2ii [symmetry code: (ii) 1 - x, -y, 1 - z] are 3.707 (9) and 3.597 (10)Å respectively, which is less than the 3.8 Å maximum value regarded as relevant for ππ interactions (Janiak, 2000).

For coordination chemistry of phenanthroline derivatives and their applications, see: Miller et al. (1999); Bodoki et al. (2009); Kane-Maguire & Wheeler (2001); Shahabadi et al. (2009). For related structures involving 2,9-dimethyl-1,10-phenanthroline, see: Alizadeh et al. (2009); Preston & Kennard (1969); Wang & Zhong (2009). For background information on ππ stacking interactions, see: Janiak (2000).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. An ORTEP (Burnett & Johnson, 1996) view of (I). Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. [Symmetry codes: (i) -x, y, 1/2 - z]
[Figure 2] Fig. 2. A view of the crystal packing of (I) showing the intermolecular ππ stacking interactions.
(2,9-Dimethyl-1,10-phenanthroline-κ2N,N')diiodidocadmium top
Crystal data top
[CdI2(C14H12N2)]F(000) = 1056
Mr = 574.46Dx = 2.349 Mg m3
Monoclinic, C2/cAg Kα radiation, λ = 0.56087 Å
Hall symbol: -C 2ycCell parameters from 25 reflections
a = 15.690 (3) Åθ = 9–11°
b = 11.580 (2) ŵ = 2.72 mm1
c = 9.836 (5) ÅT = 293 K
β = 114.65 (4)°Prism, colorless
V = 1624.3 (9) Å30.35 × 0.23 × 0.19 mm
Z = 4
Data collection top
Enraf–Nonius CAD-4
diffractometer
2306 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.020
Graphite monochromatorθmax = 28.0°, θmin = 2.2°
non–profiled ω scansh = 2625
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
k = 219
Tmin = 0.563, Tmax = 0.605l = 316
6126 measured reflections2 standard reflections every 120 min
3986 independent reflections intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.047Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.127H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.056P)2 + 2.6748P]
where P = (Fo2 + 2Fc2)/3
3986 reflections(Δ/σ)max = 0.001
88 parametersΔρmax = 1.65 e Å3
0 restraintsΔρmin = 1.30 e Å3
Crystal data top
[CdI2(C14H12N2)]V = 1624.3 (9) Å3
Mr = 574.46Z = 4
Monoclinic, C2/cAg Kα radiation, λ = 0.56087 Å
a = 15.690 (3) ŵ = 2.72 mm1
b = 11.580 (2) ÅT = 293 K
c = 9.836 (5) Å0.35 × 0.23 × 0.19 mm
β = 114.65 (4)°
Data collection top
Enraf–Nonius CAD-4
diffractometer
2306 reflections with I > 2σ(I)
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
Rint = 0.020
Tmin = 0.563, Tmax = 0.6052 standard reflections every 120 min
6126 measured reflections intensity decay: none
3986 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0470 restraints
wR(F2) = 0.127H-atom parameters constrained
S = 1.02Δρmax = 1.65 e Å3
3986 reflectionsΔρmin = 1.30 e Å3
88 parameters
Special details top

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
Cd10.50000.30673 (3)0.25000.04219 (11)
I10.63145 (2)0.40526 (3)0.49576 (4)0.06297 (13)
N10.4331 (2)0.1468 (3)0.3059 (3)0.0385 (6)
C10.3676 (3)0.1493 (4)0.3594 (4)0.0456 (8)
C20.3328 (3)0.0468 (5)0.3921 (5)0.0547 (10)
H20.28730.04950.42930.066*
C30.3655 (3)0.0567 (4)0.3697 (5)0.0546 (11)
H30.34360.12460.39430.066*
C40.4325 (3)0.0616 (3)0.3093 (4)0.0470 (9)
C50.4652 (2)0.0441 (3)0.2803 (4)0.0375 (7)
C60.4684 (4)0.1672 (4)0.2796 (5)0.0571 (11)
H60.44780.23700.30170.069*
C70.3344 (3)0.2640 (5)0.3834 (6)0.0615 (12)
H7A0.38190.29970.46980.092*
H7B0.27820.25480.39880.092*
H7C0.32150.31160.29720.092*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.0423 (2)0.03666 (19)0.0490 (2)0.0000.02046 (17)0.000
I10.0659 (2)0.0604 (2)0.0597 (2)0.02133 (15)0.02329 (16)0.01232 (14)
N10.0341 (13)0.0426 (16)0.0372 (15)0.0004 (11)0.0133 (11)0.0038 (12)
C10.0387 (16)0.057 (2)0.0416 (19)0.0006 (16)0.0175 (15)0.0072 (17)
C20.0426 (19)0.073 (3)0.045 (2)0.010 (2)0.0150 (17)0.011 (2)
C30.054 (2)0.058 (2)0.041 (2)0.0205 (19)0.0087 (17)0.0072 (18)
C40.053 (2)0.0424 (19)0.0335 (17)0.0112 (16)0.0067 (16)0.0012 (15)
C50.0385 (15)0.0361 (16)0.0292 (15)0.0038 (13)0.0053 (12)0.0004 (13)
C60.081 (3)0.0360 (18)0.044 (2)0.0105 (19)0.016 (2)0.0021 (16)
C70.059 (2)0.070 (3)0.068 (3)0.015 (2)0.039 (2)0.009 (2)
Geometric parameters (Å, º) top
Cd1—N1i2.305 (3)C3—C41.407 (7)
Cd1—N12.305 (3)C3—H30.9300
Cd1—I12.6907 (14)C4—C51.401 (5)
Cd1—I1i2.6907 (14)C4—C61.427 (6)
N1—C11.337 (5)C5—C5i1.447 (8)
N1—C51.355 (5)C6—C6i1.343 (11)
C1—C21.399 (6)C6—H60.9300
C1—C71.481 (6)C7—H7A0.9600
C2—C31.357 (7)C7—H7B0.9600
C2—H20.9300C7—H7C0.9600
N1i—Cd1—N173.05 (16)C4—C3—H3119.9
N1i—Cd1—I1107.48 (8)C5—C4—C3116.9 (4)
N1—Cd1—I1112.40 (8)C5—C4—C6119.8 (4)
N1i—Cd1—I1i112.40 (8)C3—C4—C6123.3 (4)
N1—Cd1—I1i107.48 (8)N1—C5—C4122.2 (4)
I1—Cd1—I1i129.82 (4)N1—C5—C5i118.6 (2)
C1—N1—C5119.9 (3)C4—C5—C5i119.2 (2)
C1—N1—Cd1125.3 (3)C6i—C6—C4121.0 (3)
C5—N1—Cd1114.9 (2)C6i—C6—H6119.5
N1—C1—C2120.6 (4)C4—C6—H6119.5
N1—C1—C7117.5 (4)C1—C7—H7A109.5
C2—C1—C7121.8 (4)C1—C7—H7B109.5
C3—C2—C1120.1 (4)H7A—C7—H7B109.5
C3—C2—H2119.9C1—C7—H7C109.5
C1—C2—H2119.9H7A—C7—H7C109.5
C2—C3—C4120.2 (4)H7B—C7—H7C109.5
C2—C3—H3119.9
N1i—Cd1—N1—C1179.5 (4)C2—C3—C4—C52.4 (6)
I1—Cd1—N1—C178.1 (3)C2—C3—C4—C6178.6 (4)
I1i—Cd1—N1—C170.8 (3)C1—N1—C5—C40.6 (5)
N1i—Cd1—N1—C50.37 (17)Cd1—N1—C5—C4179.5 (3)
I1—Cd1—N1—C5102.0 (2)C1—N1—C5—C5i178.9 (4)
I1i—Cd1—N1—C5109.1 (2)Cd1—N1—C5—C5i1.0 (5)
C5—N1—C1—C21.3 (6)C3—C4—C5—N11.2 (5)
Cd1—N1—C1—C2178.8 (3)C6—C4—C5—N1179.8 (4)
C5—N1—C1—C7179.3 (4)C3—C4—C5—C5i179.3 (4)
Cd1—N1—C1—C70.6 (5)C6—C4—C5—C5i0.3 (6)
N1—C1—C2—C30.0 (6)C5—C4—C6—C6i1.8 (8)
C7—C1—C2—C3179.5 (5)C3—C4—C6—C6i179.3 (5)
C1—C2—C3—C41.9 (6)
Symmetry code: (i) x+1, y, z+1/2.

Experimental details

Crystal data
Chemical formula[CdI2(C14H12N2)]
Mr574.46
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)15.690 (3), 11.580 (2), 9.836 (5)
β (°) 114.65 (4)
V3)1624.3 (9)
Z4
Radiation typeAg Kα, λ = 0.56087 Å
µ (mm1)2.72
Crystal size (mm)0.35 × 0.23 × 0.19
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionMulti-scan
(SORTAV; Blessing, 1995)
Tmin, Tmax0.563, 0.605
No. of measured, independent and
observed [I > 2σ(I)] reflections
6126, 3986, 2306
Rint0.020
(sin θ/λ)max1)0.836
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.047, 0.127, 1.02
No. of reflections3986
No. of parameters88
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.65, 1.30

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996) and DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 1999).

 

Footnotes

Current address: Department of Chemistry AN-Najah National University PO Box 7, Nablus Palestine Territories.

Acknowledgements

The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding the work through the research project No. RGP-VPP-008.

References

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