Synthesis and Magneto‐Structural Study of Distorted Octahedral CoII Complexes with Picolinamide and Azide (μ1,1)‐Bridge

• Published in: ChemistrySelect (Weinheim) 2021-02, Vol.6 (7), p.1394-1403
• Main Authors: Pastor‐Ramírez, Cándida, Zamorano‐Ulloa, Rafael, Vazquez‐Lima, Hugo, Hernández‐Anzaldo, Samuel, Reyes‐Ortega, Yasmi
• Format: Article
• Language: English
• Subjects: Analytical methods; Ascorbic acid; Poly(methacrylic acid); Sensors; Silver nanoclusters
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202004323

Two compounds [Co2(pa)2(μ1,1‐N3)2]n (1) and [Co4(pa)6(μ1,1‐N3)6] (2), (pa=picolinamide) were obtained and studied by electronic and magnetic spectroscopies. 1 is a polymer and 2 is a tetramer of mixed‐valence CoII/III. The N3− anions act as bridges between cobalt ions in the μ1,1 coordination mode. UV‐Vis spectrum analysis showed the octahedral distortion of the compounds. ESR solution spectra revealed a low‐spin ground state, s=1/2 (dz2 ) for CoII. The energy gap was J>kT between levels, S=0 to S=±1 , of 2; consequently, its transition would not be observed. 1 showed zero‐field splitting of the excited level S=±1 with D∼0.31 cm−1. Hyperfine (59Co, I=7/2) and superhyperfine (14N, I=1) couplings were observed. Magnetic susceptibility studies (3–300 K) revealed antiferromagnetic exchange interactions in 1 and 2 with exchange coupling constants, J1=−108 cm−1 and J2=−20 cm−1, g=2 and s=1/2 , for the Co(2)‐Co(2) magnetic exchange pathways. Two novel CoII complexes with picolinamide and azide as ligands were synthetized and characterized. This study demonstrates that the complexes exhibit interesting electronic and magnetic properties due to octahedral distortions that present.