THE COORDINATION CHEMISTRY OF 2-PYRIDONE AND ITS DERIVATIVES

This review covers the coordination chemistry of 2-pyridone (2-hydroxy pyridine) and its derivatives from 1968 to 1993. The derivatives studi ed have chiefly been 2-pyridone itself and those substituted in the 6- position of the ring, in particular 6-methyl-2-pyridone and 6-chloro-2 -pyridone. These ligands have found their major usage as 1,3-bridging ligands akin to carboxylates. A large number of dimeric complexes have been synthesized with elements including Cr, Mo, W, Tc, Re, Ru, Os, R h, Ir, Pd, Pt and Cu, and in which the metal-metal bond order varies f rom four to zero. The structural chemistry of these dimeric complexes is discussed, as are physical studies designed to increase the underst anding of metal-metal bonding. Larger polymetallic arrays can be made with first-row metals such as chromium, cobalt and copper. Work on pla tinum complexes of 2-pyridone has been important in modelling the inte raction of cis-[Pt(NH3)(2)Cl-2] with uracil nucleobases; this work is also reviewed, Dimeric rhodium(I) and iridium(I) complexes display int eresting photochemistry, and this work is described. A recent developm ent is the use of 2-pyridones as bridging ligands in heterometallic as semblies, especially of copper and lanthanoids and Group 2 metals.