A bisphosphonite calix[5]arene ligand that stabilizes η6 arene coordination to palladium.

Treatment of a bis(phenylphosphonite)calix[5]arene ligand with either palladium(II) chloride or 1,5-cyclooctadieneplatinum(II) chloride yields square planar metal complexes in which the two phosphorus atoms bind cis to the MCl(2) moiety (M = Pd, Pt). Chloride was removed from the palladium complex to open a coordination site at the metal for catalysis. The chloride removal resulted in a rare and unexpected η(6) coordination of an arene to the metal.

Phosphorus-based p-tert-butylcalix[5]arene ligands.

New calix[5]arene trivalent phosphorus derivatives have been synthesized which should be excellent ligands with which to study and control the interaction of a ligand atom with a metal. The larger cavity of the calix[5]arene (compared to calix[4]arene) provides a good balance between constraint and flexibility. Treatment of p-tert-butylcalix[5]arene with 2 equiv of either tris(dimethylamino)phosphine or dichlorophenylphosphine inserts two RP moieties into the calix[5]arene framework to give calix[5](PR)2(OH) (1, R = Me2N; 2, R = Ph).