Metal-metal interactions in bimetallic complexes have long been a topic of thorough investigation due to their unique photophysical and structural properties. While there have been many cases of covalent bonding between open-shell metals, fewer examples exist for covalent bonding between closed-shell (d10) and pseudo-closed shell metals. This undertaking is a direct continuation of research inspired by recent discoveries in the Omary Group of a new type of chemical bond between closed-shell d10 metal centers in a hexanuclear cluster complex, Au4Cu2 {[Au2(μ-C2,N3-EtIm)2Cu(μ-3,5-(CF3)2Pz)] as well as intramolecular polar-covalent interactions in a heterobimetallic dimer, AuCu(MTP)2. Electrostatic effects can be tuned to assist the potential of polar-covalent bonding in heterobimetallic complexes (M-M’) whereas the electronic factor of the two metals (M/M’) and/or two ligands (L/X) can be altered to engender greater mixing of (n+1)s0/p0 orbitals of M with (n)d10 orbitals of M’ en route to strengthening the M-M’ supramolecular polar-covalent bond. Although the M-M’ supramolecular polar-covalent bond is expected to form based on density functional computational predictions, formation of the bond would be at the expense of homo- or hetero- metallophilic bonding – which is shown to be weaker than the M-M’ polar-covalent bond – is cooperative in nature in extended 1-D or 2-D systems, as has been established in past publications. Where intra- and inter-molecular d10-d10 interactions in hetero- and homometallic structures have been extensively studied, the current investigation will be primarily focused on supramolecular dimers of mononuclear, sterically-unencumbered systems of the form MM’LX. Where, M/M’ = Ag/Au, L = NH3 and X = CN. Bulkier neutral L (e.g., bulkier phosphines with higher cone angle than that in PMe3) and/or X anionic ligands (e.g., o-substituted arylthiolates instead of halides or cyanide) will also be investigated in order to potentially stabilize the dimeric products instead of 1-D or 2-D extended structures. This investigation serves as a comprehensive study of potentially new metal-metal bonds in the complexes discussed above and our efforts to synthetically achieve these d10-d10 structures.

Bonding studies in supramolecular assemblies of ion-paired mononuclear ionic complexes

2019 Spring National Meeting

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