Influence of Ligand Substitution Pattern on Structure in Cobalt(II) Complexes of Bulky N,N′-Diarylformamidinate N-Oxides

• Published in: European journal of inorganic chemistry Vol. 2015; no. 1; pp. 73 - 82
• Main Authors: Cibian, Mihaela, Langis-Barsetti, Sophie, De Mendonça, Fernanda Gomes, Touaibia, Sammy, Derossi, Sofia, Spasyuk, Denis, Hanan, Garry S.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.01.2015; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Cobalt; Electronics; Isomerization; Ligands; Magnetic measurement; N,O ligands; O ligands; Physical Sciences; Science & Technology; Solid state; Solvents; Spectroscopic analysis; Spectroscopy; Stereochemistry; Structure elucidation; Substituent effects; OXIDATION; MOLECULAR CALCULATIONS; TRANSITION-METAL-COMPLEXES; EFFECTIVE CORE POTENTIALS; STABILITY; SUSCEPTIBILITY; Substituent effects; Stereochemistry; PLANAR; Cobalt; N; EQUILIBRIUM; Structure elucidation; O ligands; 4-COORDINATE
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201402895

Cobalt(II) complexes of bulky N,N′‐diarylformamidinate N‐oxide ligands were synthesized and structurally characterized. The cobalt(II) bis(chelates) are square‐planar (low spin) in the solid state, according to XRD and magnetic measurements (μeff = 1.8 to 2.1 μB), but show square‐planar (low spin) to tetrahedral (high spin: μeff = 3.5 to 4.7 μB) isomerization in solutions of noncoordinating solvents, as demonstrated by different spectroscopic techniques. The isomerization equilibrium is highly sensitive to the substitution pattern on the ligand due to a combination of steric and electronic influences. Cobalt(II) bis(chelates) of bulky N,N′‐diarylformamidinate N‐oxide ligands show isomerization from square‐planar low‐spin (in the solid state) to tetrahedral high‐spin (in solutions of noncoordinating solvents).