Synthesis of an N, N-diethyl-tert-butylazothioformamide ligand and coordination studies with Copper(I) salts

Abstract

Redox-active azothioformamides ligands rapidly coordinate to transition metals and are excellent substrates for monitoring host–guest binding interaction mechanisms as they can exhibit unique coordination complexes while producing an increase in extinction coefficient upon addition of metal salt. Herein, an alkyl derivative, N,N-diethyl-t-butylazothioformamide, was synthesized and fully characterized, including X-ray crystallography. Crystalline coordination complexes were prepared with various copper(I) salts (CuBr, CuI and [(CH3CN)4Cu]BF4 producing both 1:1 µ-X dimers from copper(I) halides and a distorted tetrahedral 2:1 species with non-coordinative tetrafluoroborate salt. Bond distances and angles suggest neutrally bound alkyl azothioformamide ligands with copper(I), indicating no redox activity upon binding. UV–Vis titration studies with copper(I) salts and subsequent data evaluation with both 1:1 and 2:1 non-linear regression binding models suggest inconsistent mechanisms with copper(I) salts.