Tris( pyrazolyl) phosphine Oxide and Tris( triazolyl)phosphine Oxide Scorpion Ligands

DFT calculations were performed on copper(I) complexes of neutral scorpion ligands based on either pyrazolyl (Pz) or triazolyl (Tz) rings with both methane and phosphine oxide apexes, that is, HC(Pz)(3), OP(Pz)(3), HC(Tz)(3), and OP(Tz)(3). The analyses reveal that all four ligands have similar donor properties and that their differences are easily compensated by the proper choice of substituents. This computational study strongly suggests that the readily synthesizable neutral phosphine oxide capped scorpion ligands should have broad applicability. Experimentally, the two OP-capped ligands act differently on copper(I) complexation. With OP(Tz)(3), a crystallographically characterized dimeric tris(triazolyl)phosphine oxide based copper(I) complex was obtained, whereas instead a monomer was reported for OP(Pz)(3).