Synthesis and characterization of two manganese(II) complexes containing di(4-pyridyl)sulfide (4-DPS) ligand: The effects of the counter ion and of the weak non-covalent interactions in the crystal structures of [Mn(4-DPS) 4(H 2O) 2](ClO 4) 2·H 2O and {[Mn(4-DPS) 2(NCS) 2] ·2H 2O} n

Abstract

From the reaction between the metallic precursor Mn(ClO 4) 2·6H 2O and the flexible ligand di(4-pyridyl)sulfide (4-DPS) a mononuclear complex [Mn(4-DPS) 4(H 2O) 2](ClO 4) 2·H 2O ( 1) was obtained, while the reaction of MnCl 2·4H 2O with 4-DPS and KSCN afforded a neutral 1-D coordination polymer namely {[Mn(4-DPS) 2(NCS) 2] ·2H 2O} n ( 2). Compounds ( 1) and ( 2) were characterized by means of elemental analysis, thermal analysis (TG/DTA), vibrational (IR and Raman) and electron paramagnetic resonance (EPR) spectroscopies. Additionally, single-crystal X-ray diffraction analysis shows that in ( 1) the 4-DPS ligand acts in the monodentate coordination mode while in ( 2) it exhibits bridging coordination mode. The crystal structure of both compounds shows that each Mn 2+ adopts a distorted octahedral geometry in which the equatorial planes contain four nitrogen atoms from different 4-DPS ligands. In ( 1), the axial positions are occupied by two oxygen atoms from two water molecules and in ( 2) by two other nitrogen atoms from two isothiocyanate groups. The supramolecular array observed in ( 1) was achieved through hydrogen-bonding and π–π interactions and in ( 2) the 1-D doubled stranded polymeric chain is extended by metal–ligand interaction. EPR spectra for both compounds are consistent with the X-ray structures containing isolated Mn 2+ ions in distorted octahedral arrangements with very weak anti-ferromagnetic coupling.