Supramolecular networks of silver(I) and iron(II) complexes of the third generation tris(pyrazolyl) methane ligand Ph-2(O)POCH2C(pz)(3) (pz = pyrazolyl ring)

摘要

The new ligand Ph-2(O)POCH2C(pz)(3) (pz = pyrazolyl ring), prepared from the reaction of HOCH2C(pz)(3) and Ph2P(O)Cl in the presence of base, reacts with either AgBF4 or Fe(BF4)(2)center dot 6H(2)O in a 2/1 molar ratio to yield {[Ph-2(O)POCH2C(pz)(3)](2)Ag}(BF4) (1) and {[Ph-2(O)POCH2C(pz)(3)](2)Fe}(BF4)(2) (4), respectively. In the structure of 1, the silver is in an unusual planar geometry with each of the ligands in a kappa(2)-kappa(0) coordination mode. Slow evaporation of a thf solution of 1 yields crystalline [Ph-2(O)POCH2C(pz)(3)Ag](2)(thf)(2)}(BF4)(2) (2). In each cationic unit of 2, the two Ph-2(O)POCH2C(pz)(3) ligands coordinate to the same two silver(I) centers in a kappa(2)-kappa(1) bonding mode, with a silver atom separation of 3.36 angstrom. The supramolecular structure of both 1 and 2 is dominated by a pair of cooperative hydrogen bonding interactions between the Ph2P(O) secondary tecton and a hydrogen atom from a methylene group situated on a neighboring building block, which arranges the cations in chains. The reaction of HC(pz)(3) and AgO3SCF3 (AgOTf) yields {[HC(pz)(3)](2)Ag-2}(OTf)(2) (3). The cationic unit in 3 has a structure very similar to that of 2, but with a much shorter distance between the silver atoms at 2.86 angstrom. The supramolecular structure of 3 is dominated by an unusual pyrazolyl embrace interaction where the acceptor ring in the C-H ... pi interaction is the pyrazolyl ring kappa(1)-bonded to silver in the adjacent dimeric unit rather than the other ring in a kappa(2)-bonded Cpz(2) unit. This interaction arranges the cations in chains which are further organized into sheets by the triflate anions that link the chains via combined Ag ... O/CH ... O interactions. The iron in 4 is octahedral with each tris(pyrazolyl) methane unit in the kappa(3)-tripodal coordination mode. The supramolecular structure is sheets formed by hydrogen bonding between the Ph2P(O) oxygen and a meta-position hydrogen on one of the diphenylphosphine rings from an adjacent cation.