Bis Pyridyl Ligands Research Articles

Diversity of chain, interwoven and network structures formed by metal complexes with 2,3,5,6-tetrafluoro-1,4-bis(4-pyridyl-sulfenyl)benzene †

The preparations are reported of a range of complexes formed by 2,3,5,6-tetrafluoro-1,4-bis(4-pyridylsulfenyl)benzene (L) with MnII, CoII, NiII, ZnII and CdII, and single crystal X-ray diffraction studies have been made on four of the compounds. In the complex CoLI2·0.5CH2Cl2, the organic ligand bridges tetrahedrally coordinated CoII centres so as to form chains. The compound Cd2L3(NO3)4 has a more complex structure in which seven-coordinate Cd centres are linked by two different types of L bridges so as to form arrays of 90-membered macrocycles comprising sheets of linked alternating enantiomeric helices. In the complexes MnL2(EtOH)2X2 (X = Br or NCS), the bis(pyridyl) ligand utilises only one of its pyridyl units to coordinate directly to the metal atom. In both cases the Mn coordination environment comprises an all-trans octahedral arrangement of two anions, two ethanol ligands and two pyridyl units derived from two different L ligands. However in both compounds the non-coordinated pyridyl units bridge adjacent Mn centres by forming hydrogen bonds to the ethanol ligands. The resulting, complex networks are, however, dramatically different. The isothiocyanate complex forms sheets of partially interpenetrating helices whereas the bromide forms a system of triply interpenetrating (4,4) nets of ‘over 2-under 2’ type. X- and Q-Band EPR spectra of the manganese complexes are reported as are relevant spectroscopic results for the other complexes.