Bis{N-[methoxy(4-methylbenzamido)methyl]-2,4-dimethylanilinido-κ2 N,O}copper(II)

In the centrosymmetric mononuclear title complex, [Cu(C18H20N2O2)2], the CuII atom is four-coordinated in a trans-CuN2O2 square-planar geometry with the N—Cu—O chelate angle being 89.97 (11)°. The dihedral angles made by the planes defined by the aromatic ring carbons of the 4-methylbenzene and 2,4-dimethylbenzene fragments with the plane defined by the chelate ring are 13.43 (15) and 82.69 (13)° respectively. The angle between the planes defined by the aromatic carbons of the two rings is 89.40 (16)°. A a weak intramolecular C—H⋯N hydrogen bond occurs.

In the centrosymmetric mononuclear title complex, [Cu(C 18 H 20 N 2 O 2 ) 2 ], the Cu II atom is four-coordinated in a trans-CuN 2 O 2 square-planar geometry with the N-Cu-O chelate angle being 89.97 (11) . The dihedral angles made by the planes defined by the aromatic ring carbons of the 4methylbenzene and 2,4-dimethylbenzene fragments with the plane defined by the chelate ring are 13.43 (15) and 82.69 (13) respectively. The angle between the planes defined by the aromatic carbons of the two rings is 89.40 (16) . A a weak intramolecular C-HÁ Á ÁN hydrogen bond occurs.

Experimental
Crystal data [Cu(C 18 Table 1 Hydrogen-bond geometry (Å , ). The interest in the synthesis and properties of transition metal complexes containing thiourea derivatives has received a significant level of attention. This is due to their significant biological activity and variation in the mode of binding. Thiourea derivatives have shown great potential in medicinal applications especially as anticancer, antifungal, antibacterial and most interestingly as anti-HIV agents (Moro et al., 2009;Rauf et al., 2009;D′Cruz et al., 2003). In this work, the title compound derived from the desulfurization of N-(4-methylbenzoyl)-N′-(2,4-dimethylphenyl)thiourea has been successfully synthesised. The molecular structure shows that the ligand acts as a bidentate chelating ligand through nitrogen and oxygen atoms (Fig. 1). The molecule is discrete and centrosymmeric about the Cu1 atom. The two ligands coordinate to the metal centre with the N1-Cu1-O1 bond angles of 89.97 (11)°. This is typical square planar geometry for a four coordinate complex. The Cu1-N1 and Cu1-O1 bond lengths are 1.963 (2) and 1.892 (2)Å, respectively, which is in agreement with a related complex (Shen et al., 1999). The bond length O1-C8 is 1.263 (3)Å, which is slightly shorter than the other bonds. This indicates the presence of partial double bond character in the this bond due to resonance effects. The C-N bond lengths of the [C9-N2 = 1.310 (4)Å, C9-N1= 1.325 (4)Å and C8-N1 = 1.313 (4)Å] groups lie in the range expected for C-N bonds with partial double bond character. This is shorter than the bond lengths for normal C-N bonds (about 1.48Å) reported in the literature (Arslan et al., 2007). The presence of strong delocalization in the chelate ring N2, C9, N1, C8 and O1 atoms, suggested the presence of a conjugated π-system along N2-C9-N1-C8-O1 which is similar to other reported carbonylthiourea derivatives (Shen et al., 1999).

Experimental
A solution of N-(4-methylbenzoyl)-N′-(2,4-dimethylphenyl)thiourea (0.51 g, 2 mmol) in DCM (30 ml) was added dropwise to a solution of copper(II) acetate monohydrate (0.17 g, 1 mmol) in MeOH (50 ml) at about 15 minutes rate in 100 ml two-necked round bottom flask with constant stirring at room temperature. The reaction was slowly put under reflux for ca. 3 hours. Reaction progress was monitored by TLC (hexane: ethyl acetate; 7:3). When the reaction had completed, the solvent was removed in-vacuo and followed by recrystallisation from DCM: MeOH (1:3) to afford dark green solid crystals. The crude product was purified by preparative TLC (hexane: acetone; 7:3) and the dark green band was collected and recrystallised from MeOH to afford the title compound (0.16 g, 24°).

Refinement
All H atoms attached to C and N atoms were fixed geometrically and treated as riding with C-H= 0.93-0.97 Å(aromatic and methylene) and N-H= 0.86 Å(amino) with U iso (H)=1.2U eq (C or N). There are highest peak 1.26Å and deepest hole 0.93Å for Br1 atom.

Figure 1
The molecular structure of (I) with the atom labeling scheme. Displacement ellipsods are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines.

Bis{N-[methoxy(4-methylbenzamido)methyl]-2,4-dimethylanilinido-κ 2 N,O}copper(II)
Crystal data [Cu(C 18  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.10 e Å −3 Δρ min = −0.43 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 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 (Å 2 )
x y z U iso */U eq