Benzothiadiazolyl‐pyridine and ‐2,2′‐bipyridine Ligands for Luminescent and Magnetic Complexes
Abstract
Abstract Two new luminescent ligands, 4‐(2‐pyridine)‐7‐methyl‐2,1,3‐benzothiadiazole (L 1 ) and 4‐(2,2‐bipyridine)‐7‐methyl‐2,1,3‐benzothiadiazole (L 2 ), based on 2,1,3‐benzothiadiazole and pyridine or bipyridine were obtained by Suzuki coupling reactions. DFT and TD‐DFT type calculations have been performed on L 1 and L 2 in order to assign their experimental UV‐visible and emission bands. Reaction of L 1 and L 2 with metal(II) chlorides (M=Zn, Mn, Cu) provided the neutral complexes of formulas [ZnL 1 Cl 2 ] ( 1 ), [Zn(L 1 ) 2 Cl 2 ] ( 2 ), [ZnL 2 Cl 2 ] ( 3 ), [MnL 2 Cl 2 ] ⋅ 0,5CH 2 Cl 2 ( 4 ) and [CuL 2 Cl 2 ] ⋅ H 2 O ( 5 ) which have been structurally characterized. The Zn(II) ions in 1 and 2 are four‐coordinate in somewhat distorted tetrahedral N 2 Cl 2 surroundings with L 1 adopting bidentate ( 1 ) and monodentate ( 2 ) coordination modes. Complexes 3 – 5 are isostructural and their metal atoms are five‐coordinate in distorted square pyramidal environments with three nitrogen atoms from the tridentate L 2 ligand and a chlorine building the basal plane and another chlorine atom occupying the apical position. The three Zn(II) complexes are strongly luminescent in solution and the solid state, while the cryomagnetic study of the paramagnetic compounds 4 and 5 in the temperature range 2.9–300 K shows a Curie‐Weiss behaviour typical of small antiferromagnetic interactions which are mediated by weak intermolecular contacts.