Synthesis and structures of CuI,II complexes with a 2,2′-bipyridine derivative bearing a (+)-3-carene moiety

The complex salt {[CuL2][Cu4I6]center dot MeCN}(n) (1) and the compound [Cu4L3I4]center dot 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 [CuL2](2+) (N3O2 polyhedron is a trigonal bipyramid) and Cu-I coordination polymers (CuI4 polyhedron is a tetrahedron) as anions. The experimental magnetic moment mu(eff) at 300 K is 1.90 mu(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-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 IC50 value for complex 2 (13.0 +/- 1.7 mu M) is substantially smaller than IC50 for compound L (30.5 +/- 0.5 mu M).