New didentate bispyrazole ligands forming uncommon eitht-ring chelates with divalent copper, zinc and cobalt

摘要

The novel ligands 1,3-bis(pyrazol-1'-yl) propane (bpp) and 1,3-bis(3'5'-dimethylpyrazol-1'-yl)propane (bdpp) have been prepared by reacting 2 equiv. of the corresponding potassium pyrazolate with 1 equiv. of 1.3dibromopropane, Compound 1,3-bis(5'methylpyrazol-1'-yl) propane(bmpp) has been prepared from bpp by lithiation at the five position and the subsequent addition of iodomethane. These new ligands form M(II) coordination compounds with the general formula [M(ligand)X_2]where X=Cl or NO_3, and M-Cu, Zn, or Co. The single-crystal -Xay structures of [Cu(bmpp)(NO_3)_2], [Cu(bdpp)Cl_2], [Zn(bdpp)Cl_2], and [Zn(bpp)Cl_2] show the ligands to act as didentate chelates forming an uncommon eight-atom chelate ring with the metal ion. In [Cu(bmpp)(NO_3)_2] each copper ion is distorted octahedrally surrounded, whereas the metal ions in the chloride complexes have distorted tetrahedral geometries. The spectral properties are in accord with the structural data