Synthesis, characterization, and crystal structure of mercury(II) complex containing new phosphine oxide salt

The reaction of new phosphonium-phosphine oxide salt [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]Br (1) with mercury(II) iodide in a methanolic solution yielded [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2[Hg2I5Br](2). These two compounds were fully characterized by elemental analysis, IR, 1H, 31P, and 13C NMR spectra. Crystal and molecular structure of 2 has been determined by means of X-ray diffraction. In mercury compound, the phosphine oxide salt is found as a counter ion letting the mercury(II) ion to bound halides to all four coordination sites and to give dimermercurate(II) ions as the structure-constructing species. The neighboring [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2+cations are joined together by intramolecular CH⋯O hydrogen bonds to give a 1-D chain structure along the crystallographic b-axis. The [Hg2I5Br]2−anions act as cross-linkers between neighbouring strands extending the supramolecular structure into 2D layers in (110) planes as well as balances the charge of the complex. The significant effects of CH⋯X (XO, Br and I) and π⋯π aromatic interactions play a major role in the crystal packing of compound 2.