Two New closo- or nido- Carborane Diphosphine Complexes: Synthesis, Characterization and Crystal Structures

Two new carborane complexes containing closo- or nido- carborane diphosphine ligands with the formula: complex [Hg(7,8-(PPh2)(2)-7,8-C2B9H10)2] CH2Cl2 (1) and [Ag-2(mu-Cl)(2)(1,2-((PPr2)-Pr-i)(2)-1,2-C2B10H10)(2)] (2) have been synthesized and characterized by elemental analysis, H-1 and C-13 NMR spectroscopy and X-ray structure determination. The X-ray structure analyses revealed that the carborane diphosphine ligand was degraded from closo-1,2-(PPh2)(2)-1,2-C2B10H10 to nido-[7,8-(PPh2)(2)-7,8-C2B9H10](-) in complex 1, while the closo nature of the starting ligand 1,2-((PPr2)-Pr-i)(2)-1,2-C2B10H10 was retained in complex 2. In either of the two complexes, the carborane diphosphine ligand was coordinated bidentately to the Hg(II) or Ag(I) center through its two phosphorus atoms, therefore forming a five-member cheating ring between the carborane ligand and the metal center. The coordination geometry of the metal atom is distorted tetrahedron formed by P-4 unit in complex 1 and P2Cl2 unit in complex 2, respectively.