Hydrotris(3-neopentylpyrazol-1-yl)borates: a new type of sterically hindered poly(pyrazolyl)borates

The new ligand hydrotris(3-neopentylpyrazol-1-yl)borate (=L * ) was synthesized and found useful in preparing heteroleptic L * ML compounds, by the reaction of its stable L * MCl derivatives with L - . Examples of L included pseudohalides, in which case L * ML complexes were tetrahedral,various tris(pyrazolyl)borates, which led to octahedral complexes of C 3υ symmetry, and H 2 B(3,5-Me 2 pz) 2 , which yielded complexes containing five N-bonds to the metal.