Bis(diphenyl-p-tolylphosphane-κP)(2-hydroxy-3,5,7-bromocyclohepta-2,4,6-trienonato-κ2 O,O′)copper(I)

The CuI atom in the title compund, [Cu(C7H2Br3O2)(C19H17P)2], is located on a twofold rotation axis; the 3,5,7-tribromotropolonate anion coordinates as a bidentate ligand with a bite angle of 76.42 (9)°. An intramolecular C—H⋯O interaction occurs. Within the crystal, extensive weak C—H⋯π interactions contribute to the herringbone pattern observed in the packing of the molecules.

The Cu I atom in the title compund, [Cu(C 7 H 2 Br 3 O 2 )-(C 19 H 17 P) 2 ], is located on a twofold rotation axis; the 3,5,7tribromotropolonate anion coordinates as a bidentate ligand with a bite angle of 76.42 (9) . An intramolecular C-HÁ Á ÁO interaction occurs. Within the crystal, extensive weak C-HÁ Á Á interactions contribute to the herringbone pattern observed in the packing of the molecules.

Comment
Tropolone and its derivatives have been of interest ever since their first discovery in the early 1940's (Dewar, 1945); they are known to have applications in both pharmacology (Hill & Steyl, 2008) and catalysis (Crous et al., 2005). Bis troplolonato copper(II) complexes are most frequently reported (Ho, 2010;Ho et al., 2009;Chipperfield et al., 1998;Hasegawa et al., 1997). Recently, reseach in this area has been extended to include copper(I) phosphine metal complexes and the effect the troplonato ligand has on the solid state and chemical behaviour of these complexes (Steyl, 2007;Steyl & Roodt, 2006;Roodt et al., 2003). In this paper, the structure of the tropolonato-bis[diphenyl(p-tolyl)phosphine]copper(I) complex is reported (Fig. 1).
The Cu-O and Cu-P bond distances were found to be 2.090 (1) Å and 2.229 (1) Å respectively and are well within comparable ranges for copper(I) phosphine complexes. the bond angles about the Cu atom show significantly distorted tetrahedral coordination (Table 1). The bidentate bite angle O2-Cu-O2 i observed at 76.42 (9)° is close to analogous angles in previously reported structures (Steyl, 2009).
The title compound (I) displays intramolecular C-H···Br interactions with a distance of 3.4666 (5) Å as seen in Figure   2. Figure 3 illustrates the packing diagram for compound (I), a zigzag pattern is adopted with inverted repeating units creating diagonals in all directions. This intricate design is achieved though numerous C-H···π itermolecular interactions see Figure 4. These interactions occur between methyl H atoms of the p-tolyl and phenyl π, phenyl H to p-tolyl π, phenyl H to phenyl π and p-tolyl π to p-tolyl The C-H···π itermolecular interactions range from 3.1816 (1) Å -3.7267 (2) Å.
Experimental 3,5,7-Tribomotropolone (0.3 mmol) was dissolved in methanol (20 ml). To this solution was added Bis(diphenyl(p-tolyl)phosphine) copper nitrate (0.3 mmol). The resulting mixture was stirred at room temperature for 30 minutes before filtering. The filtrate was then slowly evaporated yielding crystals siutable for X-ray diffraction after 48 h.

Refinement
Hydroge atoms were placed in calculated positions, and were allowed to ride on their parent C atoms.
The final difference Fouier map had a peak/hole in the vicinity of Br1.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.