Synthesis and Structural Characterization of Copper Complexes Containing “R-Substituted” Bis-7-Azaindolyl Borate Ligands

The coordination chemistry of scorpionate ligands based on borates containing the 7-azaindole heterocycle is relatively unexplored. Thus, there is a requirement to further understand their coordination chemistry. This article outlines the synthesis and characterization of a family of complexes containing anionic flexible scorpionate ligands of the type [(R)(bis-7-azaindolyl)borohydride](−) ([(R)Bai](−)), where R = Me, Ph or naphthyl. The three ligands were coordinated to a series of copper(I) complexes containing a phosphine co-ligand to form the complexes, [Cu((Me)Bai)(PPh(3))] (1), [Cu((Ph)Bai)(PPh(3))] (2), [Cu((Naphth)Bai)(PPh(3))] (3), [Cu((Me)Bai)(PCy(3))] (4), [Cu((Ph)Bai)(PCy(3))] (5) and [Cu((Naphth)Bai)(PCy(3))] (6). Additional copper(II) complexes, namely, [Cu((Me)Bai)(2)] (7) and [Cu((Ph)Bai)(2)] (8), were obtained during attempts to obtain single crystals from complexes 4 and 2, respectively. Complexes 7 and 8 were also prepared independently from CuCl(2) and two equivalents of the corresponding Li[(R)Bai] salt alongside an additional complex, namely, [Cu((Naphth)Bai)(2)] (9). The copper(I) and copper(II) complexes were characterized using spectroscopic and analytical methods. Furthermore, a crystal structure was obtained for eight of the nine complexes. In all cases, the boron-based ligand was found to bind to the metal centers via a κ(3)-N,N,H coordination mode.