Synthesis, structure, optical and magnetic properties of [CrL(X)3], {L = 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine; X = Cl−, N3−, NCS−}

Three complexes of composition [CrL(X)3], where L = 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine and X = Cl−, N3−, NCS− are synthesized. They are characterized by IR, UV–Vis, fluorescence, EPR spectroscopic, and X-ray crystallographic studies. Structural studies reveal that the Cr(III) ion is coordinated by three N atoms of L in a meridional fashion. The three anions occupy the other three coordination sites completing the mer-N3Cl3 (1) and mer-N3N3 (2 and 3), distorted octahedral geometry. The Cr–N2 has a shorter length than the Cr–N1 and Cr–N3 distances and the order Cr–N(NCS−) < Cr–N(N3−) < Cr–Cl is observed. They exhibit some of the d–d transitions in the visible and intra-ligand transitions in the UV regions. The lowest energy d–d transition follows the trend [CrLCl3] < [CrL(N3)3] < [CrL(NCS)3] consistent with the spectrochemical series. In DMF, they exhibit fluorescence having π → π∗ character. All the complexes show a rhombic splitting as well as zero-field splitting (zfs) in X-band EPR spectra at 77 K.

Three complexes of composition [CrL(X)3], where L = 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine and X = Cl−, N3−, NCS−, are synthesized. Optical, magnetic and X-ray crystallographic studies are reported.Figure optionsDownload as PowerPoint slide