New homo- and hetero-bimetallic assemblies based on 2,5-bis(4-carboxyphenylamino)-3,6-dichloro-1,4-benzoquinone: synthesis, characterization, and magnetic properties

Abstract

Synthesis, characterization, and magnetic properties of a new series of dinuclear compounds M^IIM′^IIL₂(H₂O)₄ (where M^II, M′^II= Mn (1), Ni (2), Cu (3) and M^II= Cu, M′^II= Co (4), Ni (5); LH₂ = 2,5-bis(4-carboxyphenylamino)-3,6-dichloro-1,4-benzoquinone) are reported. These complexes were characterized by elemental analyses, FAB mass spectra, thermogravimetric analysis, spectroscopic techniques (infrared, NMR, UV-Vis), and powder XRD studies. Magnetic properties investigated by SQUID magnetometer show antiferromagnetic coupling between the metal centers connected by the extensive π-delocalized ligand. Magnetic coupling constants (J) ranging from −1.01 to −3.01 cm⁻¹ based on the Hamiltonian H = −2JS _i S _j have been obtained. The optimized geometry of the ligand derived from DFT is also reported.

Keywords:

• Bimetallic assemblies
• Bicarboxylate ligand
• SQUID
• Magnetic properties
• π-Delocalized
• Coupling constant
• DFT

Acknowledgments

The authors thank the Head, Department of Chemistry, Banaras Hindu University, Varanasi, for providing laboratory facilities. The authors are grateful to Mr Suryanarayan Das and Mr Kranti Kumar Sharma for their help in the magnetic data recording. Thanks are also due to I.T.(B.H.U.) for powder X-ray data, CDRI, Lucknow for FAB-MS, SAIF IIT, Mumbai for TGA analysis, Mr Satish Tiwari for CHN analyses and Mr V.N. Pandey for IR and electronic spectra recording. One of the authors (KRR) thanks BHU for research scholarship.