Chemistry of the Group 1B metals. Part 16. Crystal and molecular structures of [ortho-phenylenebis(dimethylarsine)][tetrakis(1-pyrazolyl)borato-N ²,N²′]copper(I) and bis[ortho-phenylenebis(dimethylarsine)]-copper(I) hexafluorophosphate(V)

The crystal structures of the title compounds, [Cu{(AsMe₂)₂C₆H₄-o}{(C ₃H₃N₂)₄B}], (1) and [Cu{(AsMe₂)₂C₆H₄-o} ₂][PF₆], (2) have been determined by single-crystal X-ray diffraction methods at 295 K and refined by least squares to residuals of 0.037 and 0.038 for 3 005 and 702 independent 'observed' reflections respectively. Crystals of (1) are monoclinic, space group P2₁/n, with a = 12.819(4), b = 17.388(10), c = 12.042(6) Å, β = 93.22(4)°, and Z = 4. The complex is mononuclear and comprises a copper(I) species in a four-co-ordinate environment, each ligand acting as a chelate. The potential symmetry of the system is lost because of steric interactions between the ligand substituents: Cu-As, 2.370(1), 2.333(1); Cu-N, 1.987(4), 2.016(4) Å. Crystals of (2) are orthorhombic, space group Fddd, with a = 21.35(1), b = 20.46(1), and c = 13.262(9) Å. The cation and anion each have 222 symmetry although the latter is disordered. The copper atom of the cation is co-ordinated by the two bidentate arsine ligands, Cu-As, 2.360(1) Å, the interligand angular geometry being irregular [As-Cu-As, 113.64(5), 126.39(6)°].