Towards dimetallic biologically inspired aerobic oxidation catalysts

We report herein the synthesis and properties of a range of group 8 dimetallic paddlewheel complexes incorporating a range of formamidinate and amidate ligands. The potential of some of these complexes as aerobic oxidation catalysts is explored and the electronic structures probed via the aid of DFT calculations under B3LYP and PBE0 on the model complex Ru2(dmf)4 (where dmf = N,N’-diphenylformamidinate). Attempts to extend a previous synthetic precedent for the synthesis of Fe2(II,II)(DPhF)4 (where DPhF = N,N’-Diphenylformamidine) to other diiron tetra-formamidinates are reported, and the structure of the first novel symmetrically basic beryllium acetate structured tetra-iron cluster species Fe4(II)(O)(DMOPhFm)6 (IX) (where DMOPhFm = N,N’-bis(3,5-dimethoxyphenyl)formamidine) published.

An alternative assignment for the redox process observed in the cyclic voltammogram of Ru2(II,II)(formamidinate) complexes is reported as evidenced by UV-Vis spectroelectrochemical analysis. Additionally, the nature of an unknown reversible interaction of the species Ru2(II,II)(DMOPhFm)4 (X) and Ru2(II,II)(4FPhFm)4 (XI) (where 4FPhFm = N,N’-bis(4-flourophenyl)formamidine) on exposure to dioxygen is explored by a wide range of analytical techniques. A provisional computational model of this interaction is proposed and compared to the available data but requires some further refinement in order to better model the phenomenon observed experimentally.