(3-Chloropropyl)triphenylphosphonium bromide

The title compound, C21H21ClP+Br−, is the bromide salt of a mixed aryl-alkyl phosphonium cation. C–P–C angles span a range of 107.20 (10)–111.18 (10)°. The non-H atoms of the 3-chloropropyl group adopt a staggered conformation [C–C–C–Cl torsion angle: −72.0 (3)°]. In the crystal, C—H⋯Br contacts connect the entities of the title compound into a double zigzag chain along b. These chains are linked into a supramolecular layer lying parallel to (10-1) by C—H⋯π interactions.

The title compound, C 21 H 21 ClP + Br À , is the bromide salt of a mixed aryl-alkyl phosphonium cation. C-P-C angles span a range of 107.20 (10)-111.18 (10) . The non-H atoms of the 3chloropropyl group adopt a staggered conformation [C-C-C-Cl torsion angle: À72.0 (3) ]. In the crystal, C-HÁ Á ÁBr contacts connect the entities of the title compound into a double zigzag chain along b. These chains are linked into a supramolecular layer lying parallel to (101) by C-HÁ Á Á interactions.
The phosphorus atom is coordinated tetrahedrally. The C-P-C angles span a range of 107.20 (10)-111.18 (10)° with the smallest angle found in between two phenyl groups and the largest angle in between a phenyl and the 3-chloropropyl group. The non-hydrogen atoms of the 3-chloropropyl group adopt a staggered conformation, the corresponding C-C-C-Cl angle is found at -72.0 (3)° (Fig. 1).
In the crystal, two C-H···Br contacts whose range falls by more than 0.1 Å below the sum of van der Waals radii of the corresponding atoms are observed. These are supported by a hydrogen atom of a phenyl group as well as a hydrogen atom of the methylene group directly bonded to the phosphorus atom. In terms of graph-set analysis (Etter et al., 1990;Bernstein et al., 1995), the descriptor for these contacts is DD on the unary level. Furthermore, a C-H···π contact stemming from one of the H atoms on a phenyl group is observed. Taking into account only the contacts that involve the bromide ion, the entities of the title compound are connected to a double zigzag chain along the crystallographic b axis.
Metrical parameters as well as information about the symmetry of these contacts are summarized in Table 1. The shortest intercentroid distance between two aromatic systems was measured at 4.8882 (16) Å and is apparent between one of the phenyl groups and its symmetry-generated equivalent (Fig. 2).
The packing of the title compound in the crystal is shown in Figure 3.

Experimental
The title compound was obtained as a gift sample from R. L. Fine Chem., Bengaluru, India. The compound was recrystallized from methanol by slow evaporation at room temperature and was used as such for diffraction studies.

Refinement
Carbon-bound H atoms were placed in calculated positions (C-H 0.95 Å for aromatic carbon atoms, C-H 0.99 Å for methylene groups) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U eq (C).

Figure 1
The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level).