A　new　mercury　iodide　complex　of　dppf,　[HgI2(dppf)]　(adduct　1,　dppf　=　1,1-bis(diphenylphosphino)-ferrocene)　was　prepared　and　characterized.　Single　crystal　Xray　diffraction　analysis　established　that　the　compound　crystallizes　in　the　monoclinic　system,　space　group　C2c,　with　a　=　34.992(3),　b　=　10.236(5),　c　=　18.765　(4)　A,　beta　=　99.410(2)degrees,　Z　=　8,　V　=　6631.2(9)　Angstrom(3).　The　coordination　about　the　mercury　atom　is　tetrahedral　with　two　equivalent　Hg-I　and　Hg-P　bonds.　Dppf　functions　as　a　chelating　ligand.　The　nonlinear　optical　(NLO)　properties　were　studied　with　an　8　ns-pulsed　laser　at　532　rim.　Its　optical　responses　to　the　incident　light　exhibit　weak　optical　absorptive　and　strong　refractive　effects,　with　n(2)　=　6.86　x　10(-18)　m(2).W-1　in　a　2.48　x　10(-4)　mol.dm(-3)　DMF　solution.