Multimetallic complexes that feature two metals in close proximity (&lt; 5 Å) are useful in a range of applications, including electrochemical transformations of small molecules. However, such compounds can be challenging to prepare and characterize, as their properties depend on multiple metals. To gain insight into how the chemistry of a redox-active metal center is modulated by a closely spaced Lewis-acidic redox-inactive metal, we have prepared a series of heterobimetallic complexes. In our approach, nickel was first coordinated into the Schiff base cavity of a previously known ditopic ligand, and then a range of redox-inactive cations (M) were installed in a pendant crown ether-like site. Structural data for these new compounds indicate that the Ni–M distances depend on the identity of the redox-inactive metal. Importantly, electrochemical data reveal a trend in the reduction potentials of these complexes that tracks with the Lewis acidity of the redox-inactive cations. Studies examining the stability of these heterobimetallic complexes in several solvents will also be discussed. Taken together, these results provide new insights into building stable and tunable bimetallic catalysts containing highly Lewis-acidic trivalent redox-inactive cations.

Reduction potential and stability trends in heterobimetallic complexes containing trivalent redox-inactive cations

255th National Meeting (2018)

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