New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C 2 NAP Mes )

The synthesis and characterization of dissymmetric Co III ‐bis‐alkynyl complexes supported by cyclam (1,4,8,11‐tetraazacyclotetradecane) are reported. A series of trans ‐[Co(cyclam)(C 2 NAP R )Cl]Cl were prepared from the reaction between [Co(cyclam)Cl 2 ]Cl and HC 2 NAP R in the presence of Et 3 N, where NAP R is N ‐R‐1,8‐naphthalimide with R as mesityl (Mes, 1a ), methyl (Me, 1b ), 1‐ethylpropyl (Pen, 1c ), 2‐ethylhexyl (2‐ethhex, 1d ), or n ‐octyl (Oct, 1e ). Treating compounds 1a and 1b with AgOTf in NCCH 3 resulted in trans ‐[Co(cyclam)(C 2 NAP R )(NCCH 3 )](OTf) 2 ( 2a and 2b , respectively), while reactions with 1c , 1d and 1e under the same conditions yielded only intractable mixtures. More soluble 2a reacted further with HC 2 Ar in the presence of Et 3 N to afford trans ‐[Co(cyclam)(C 2 NAP R )(C 2 Ar)](OTf) with Ar as C 6 H 4 ‐4‐NMe 2 ( 3a ), NAP Mes ( 3b ) and Ph ( 3c ). All new complexes were characterized using X‐ray diffraction ( 1a , 1c and 3b ), IR, 1 H NMR, UV/Vis and fluorescent spectroscopy, and cyclic voltammetry.