7-Azaindol-7-ylborate: A Novel Bidentate N^BH₃ Chelating Ligand

7-Azaindole (H-azain) reacts with sodium borohydride (NaBH4) to yield the sodium salt of the novel 7-azaindol-7-ylborate anion (7-azain-7)BH3−, two rhodium derivatives of which reveal distinct coordination modes  [Rh{κ2N,H-H3B(7-azain-7)}(CO)(PPh3)2] and [Rh{κ3N,H,H′-H3B(7-azain-7)}(PPh3)2]thereby demonstrating how the variable denticity of the ligand may accommodate the varying electronic requirements of the metal center.