Acac and Related Ligands

Complexes of Acac and Related Ligands.—Isomerisation of complexes of acac and of its fluoro-derivatives tfac and hfac is generally intramolecular. Whether the mechanism involves reversible dissociation of one end of the ligand molecule or simply twisting without any bond breaking, is still a matter for discussion and dispute. The isolation and kinetic study of aquation intermediates containing monodentate en and mono- or 

Stieger, G. M. Harris, and H. Kelm, Ber, Bunsengesellschaft Phys. Chem., 1970, 

Tropolonates are structurally analogous to acac complexes. Their mechanisms of isomerisation or rearrangement can also be monitored by variable temperature n.m.r. studies.  

Inversions.—Currently there is considerable interest in comparing rates of inversion at nitrogen with rates of hydrogen exchange for cobalt(m) and for platinum(ii) complexes of ethylenediamine derivatives. Previous work has suggested that, whereas in cobalt(iii) systems rates of hydrogen exchange 

There remain to report two further examples — inversion at cobalt(ii) in the complex Co(acac)2(4,7-diMe phen), and intramolecular rearrangement in edta complexes of uranium.  

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Chelate molecules and ions containing acac and related ligands... 

Complexes of acac and Related Ligands.—Mechanisms of isomerization of -diketone complexes have been the subject of a review. Two studies of isomerization and racemization rates of diketone complexes establish orders of relative reactivity for complexes of various cations. For complexes M(tfac)a, rates of isomerization are in the following order ... 

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