The first examples of half-sandwich Rh(i) complexes stabilized by borane coordination have been prepared and structurally characterized. As substantiated by NMR spectroscopy and single-crystal X-ray diffraction, the phosphine-borane ligand iPr2P-(o-C6H4)-BFxyl2 1 [Fxyl = 3,5-(F3C)2C6H3] engages in tight η3-BCC or η1-B coordination, depending on the metal environment.