The unsymmetrical phosphorus ylide, Ph 2 PCH 2 CH 2 PPh 2 @C(H)C(O)Ph is shown to react with Hg(II) halides to form polymeric products with the composition {HgX 2 [PPh 2 CH 2 CH 2 PPh 2 C(H)C(O)Ph]} n , where X = Cl (1), Br (2), I (3). The complexes have been characterized by elemental analysis, IR, 1 H, 31 P NMR spectra as well as by ESI mass spectra. In product 1 the ylide exhibits a P, C-bridging mode of coordination, while in 2 and 3 it shows a monodentate P-coordination with the dangling ylide. The structure of complex 3 has been characterized crystallographically. The monomeric -Hg-I-Hg-bridging in 3 leads to a zig-zag polymeric chain in which mercury assumes a distorted tetrahedral geometry.