Synthesis and structures of Cu{sup I,II} complexes with a 2,2´-bipyridine derivative bearing a (+)-3-carene moiety

The complex salt {[CuL_2][Cu_4I_6]•MeCN}{sub n} (1) and the compound [Cu{sub 4}L{sub 3}I{sub 4}]•3 MeCN (2) (L is a chiral ligand bearing a natural monoterpene (+)-3-carene moiety) were synthesized. The crystal structures of compounds 1 and 2 were determined by X-ray diffraction. The structure of compound 1 consists of complex cations [CuL{sub 2}]{sup 2+} (N{sub 3}O{sub 2} polyhedron is a trigonal bipyramid) and Cu{sup I} coordination polymers (CuI{sub 4} polyhedron is a tetrahedron) as anions. The experimental magnetic moment μ{sub eff} at 300 K is 1.90 μ{sub B}, which is consistent with the X-ray diffraction data and the assumption that compound 1 is mixed-valence. The structure of compound 2 comprises a tetranuclear Cu{sup I} complex, in which three Cu atoms are coordinated by two N atoms of the ligand L and two I atoms, and the fourth Cu atom is coordinated by four I atoms (coordination polyhedra are distorted tetrahedra). Compounds L and 2 were found to influence the viability of human laryngeal carcinoma cells (Hep2). The IC{sub 50} value for complex 2 (13.0±1.7 μM) is substantially smaller than IC{sub 50} for compound L (30.5±0.5 μM).