text: A range of tripodal phosphines such as HC(CHPR), N(CHCHPPh) and P(CHCHPMe) have been reviewed. The tetra amine (tris(2-aminoethyl)amine) can be reacted with salicylaldehyde to form a ligand which can bind with three oxygens and three nitrogens to a metal. Trispyrazolylmethane (Tpm) is another class of scorpionate ligands, notable for having identical geometry and very similar coordination chemistry to Tp with only a difference in charge between them. Another variation is the Trisoxazolinylborate ligand.
  Hydrotris(pyrazolyl)aluminate (Tpa) complexes have similar coordination geometries to Tp complexes, however Tpa ligands are more reactive due to the weaker Al-N and Al-H bonds, compared to B-N and B-H bonds of Tp ligands, which results in either Tpa ligand transfer, pyrazolate transfer, or hydride transfer with MX (M = Mg, Mn, Fe, Co, Ni, Cu, Zn; X = Cl, Br).