Complexation of the antihypertensive drug oxprenolol with copper(II)

The complexation between copper(II) and the antihypertensive drug oxprenolol (HOxp) was studied both in methanol and slightly alkaline aqueous media at Cu:HOxp molar ratio from 1:1 to 1:10. Copper(II) forms two types of complexes–a mononuclear violet one, CuOxp 2, with bidentately bound ligands and a green dimeric one, Cu 2Oxp 2Cl 2, in which the two Cu(II) centres are linked by the ligand through oxygen bridges. The crystal structure of the Cu 2Oxp 2Cl 2 complex consists of two crystallographically non-equivalent centrosymmetric copper dimers. Each copper atom is four-coordinated in a distorted square-planar environment. The Cu 2O 2 structural core is characterized by a Cu1–O1–Cu1′ angle of 104.15(13)° (Cu2–O2–Cu2′ 104.30(13)°) and a relatively short Cu1–Cu1′ separation of 3.026(1) Å (Cu2–Cu2′−3.023(1) Å). Magnetic susceptibility and EPR measurements indicate an antiferromagnetic coupling of the copper(II) centers.