2-Substituted <i>m</i>-Xylylene-Bridged Dicobaloximes: Structure−Property Relationship Using Variable-Temperature ¹H NMR Study^†

m-Xylylene-bridged dicobaloximes with a substituent at the 2-position having varying electronic and steric properties have been synthesized and characterized by 1H and 13C NMR spectroscopy. The variable-temperature 1H NMR study of these complexes shows that the electronic cis influence is an important phenomenon for the Co−C bond rotation. The coalescence temperature of the dioxime protons correlates well with the ortho substituent constant. The crystal structure of a 2-nitro-m-xylylene-bridged dicobaloxime, Py(dmgH)2Co-CH2-(2-NO2-1,3-C6H3)-CH2-Co(dmgH)2Py, is reported. The X-ray structural data support the 1H NMR findings.