The paddlewheel [Ru2Cl(O2CCH3)4] complex was previously reported to react with
the model
protein hen egg white lysozyme (HEWL), forming adducts with two diruthenium
moieties bound to Asp101 and Asp119 side chains upon the release of
one acetate. To study the effect of the equatorial ligands on the
reactivity with proteins of diruthenium compounds, X-ray structures
of the adducts formed when HEWL reacts with [Ru2Cl(D-p-FPhF)(O2CCH3)3] [D-p-FPhF = N,N′-bis(4-fluorophenyl)formamidinate]
under different conditions were solved. [Ru2Cl(D-p-FPhF)(O2CCH3)3] is bonded
through their equatorial positions to the Asp side chains. Protein
binding occurs cis or trans to D-p-FPhF. Lys or Arg
side chains or even main-chain carbonyl groups can coordinate to the
diruthenium core at the axial site. Data help to understand the reactivity
of paddlewheel diruthenium complexes with proteins, providing useful
information for the design of new artificial diruthenium-containing
metalloenzymes with potential applications in the fields of catalysis,
biomedicine, and biotechnology.