Combining a Phenanthroline Moiety with Peralkylated Guanidine Residues: Homometallic Cu II , Ni II and Zn II Halide Complexes with Site‐Differentiating Janus Head Ligands

• Published in: European journal of inorganic chemistry 2018-12, Vol.2018 (48), p.5176-5190
• Main Authors: Ortmeyer, Jochen, Vukadinovic, Yannik, Neuba, Adam, Flörke, Ulrich, Henkel, Gerald
• Format: Article
• Language: English
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201800905

The unique core portion of Janus head pro‐ligands based on a tailored phenanthroline‐bis(guanidine) architecture has been utilized to generate a multiplicity of homometallic copper(II), nickel(II) and zinc(II) complexes terminated by halide constituents. The bis‐bidentate nitrogen donor ligands provide coordination sites with metal‐differentiating properties which can be loaded successively starting with the phenanthroline interface as can be demonstrated by mononuclear species which form under metal deficient conditions. Furthermore, depending on both the alkylation and metalation stage of the guanidine residues comprising variants with tetramethyl‐, tetraethyl‐, dimethylethylene‐, and dipentylene‐guanidino functionalities, a unique diversity of bi‐ and tetranuclear complexes with multifarious coordination geometries is accessible. The resulting complexes were characterized by low‐temperature X‐ray crystallography, and their redox behavior and magnetochemical properties in solution were analyzed via cyclic voltammetric and NMR techniques (Evans method). In this way, a remarkable equilibrium between the neutral phenanthroline‐bis(guanidine) copper(II) complex (X 2 Cu II ‐phenGua‐Cu II X 2 ) and the radical monocationic phenanthroline‐bis(guanidine) copper(I)/copper(II) [X 2 Cu II ‐phenGua + · ‐(Cu I X 2 ) – ] species was identified which affects the chemical characteristics of the presented compounds in solution.