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)(PPh3)] (1), [Cu((Ph)Bai)(PPh3)] (2), [Cu((Naphth)Bai)(PPh3)] (3), [Cu((Me)Bai)(PCy3)] (4), [Cu((Ph)Bai)(PCy3)] (5) and [Cu((Naphth)Bai)(PCy3)] (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 CuCl2 and two equivalents of the corresponding Li[RBai] 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 kappa(3)-N,N,H coordination mode.

Automated summary

This article focuses on the synthesis and characterization of a series of complexes containing scorpionate ligands based on borates with the 7-azaindole heterocycle, and investigates their coordination chemistry with copper(I) and copper(II). The copper(I) and copper(II) complexes were characterized using spectroscopic and analytical methods, and crystal structures were obtained for eight of the nine complexes. The boron-based ligand in all complexes was found to coordinate to the metal centers via a kappa(3)-N,N,H mode.