Copper(I)-Purine-Phosphine Complexes. Syntheses and Molecular Structures of [Cu(2)(&mgr;-HL(1))(2)(&mgr;-dppm)(eta(1)-dppm)(2)] and {[Cu(3)(&mgr;(3)-Cl)(2)(&mgr;-dppm)(3)][Cu(HL(2))(2)]} (H(2)L(1) = 8-Mercaptotheophylline and H(2)L(2) = 8-Ethyl-3-methylxanthine).

The syntheses and molecular structures of two novel polynuclear copper(I)-purine-phosphine complexes are reported. The first one is a dinuclear [Cu(2)(&mgr;-HL(1))(2)(&mgr;-dppm)(eta(1)-dppm)(2)] complex (H(2)L(1) is 8-mercaptotheophylline). The compound crystallizes in the triclinic system, space group P&onemacr;, with cell constants a = 12.342(5) Å, b = 15.255(5) Å, c = 24.972(5) Å, alpha = 74.31(2) degrees, beta = 78.62(2) degrees, gamma = 72.51(2) degrees, and Z = 2. The structure of this complex exhibits as the most important feature the simultaneous presence of eta(1)-terminal and eta(2)-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 {[Cu(3)(&mgr;(3)-Cl)(2)(&mgr;-dppm)(3)][Cu(HL(2))(2)]} complex (H(2)L(2) is 8-ethyl-3-methylxanthine), which crystallizes in the monoclinic system, space group P2(1)/n, with cell constants a = 15.829(6) Å, b = 22.801(7) Å, c = 28.569(6) Å, beta = 97.65(4) degrees, 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.