Copper ( I ) - Purine - Phosphine Complexes . Syntheses and Molecular Structures of [

The syntheses and molecular structures of two novel polynuclear copper(I)-purine-phosphine complexes are reported. The first one is a dinuclear [Cu2(μ-HL)2(μ-dppm)(η-dppm)2] complex (H2L is 8-mercaptotheophylline). The compound crystallizes in the triclinic system, space group P1h, with cell constants a ) 12.342(5) Å, b ) 15.255(5) Å, c ) 24.972(5) Å, R ) 74.31(2)°, â ) 78.62(2)°, γ ) 72.51(2)°, and Z ) 2. The structure of this complex exhibits as the most important feature the simultaneous presence of η1-terminal and η2-bridging dppm ligands, which is first here described for a copper complex. This complex is also of interest because of its reversible photochromic behavior in the solid state. The second compound is an ionic {[Cu3(μ3-Cl)2(μ-dppm)3][Cu(HL)2]} complex (H2L is 8-ethyl-3-methylxanthine), which crystallizes in the monoclinic system, space group P21/n, with cell constants a ) 15.829(6) Å, b ) 22.801(7) Å, c ) 28.569(6) Å, â ) 97.65(4)°, and Z ) 6. The structure of this complex consists of trinuclear copper(I) cations and mononuclear [Cu(purine)2] anions, exhibiting a linear stereochemistry. As far as we know, this compound represents the first example of a copper(I)-purine complex whose structure has been determined by X-ray crystallography.