Trends in Metallophilic Bonding in Pd–Zn and Pd–Cu Complexes

Metallophilic interactions stabilize
the bond between closed-shell
metal centers, which electrostatically repel one another. Since their
introduction, the origin of these interactions has been argued to
be either London dispersion forces or dative bonding, but as yet,
there is no definitive answer. Insight into the nature of metallophilic
bonding would provide the key for rational tuning of the stabilizing
interaction, for example, in specific transmetalation transition states.
We now report on a computational study focused on the metallophilic
d8–d10 bond in recently published families
of Pd­(II)–Cu­(I) and Pd­(II)–Zn­(II) heterobimetallic compexes.
We show that dative bonding outweighs dispersion interaction in controlling
the metallophilic bonding energy in the studied heterobimetallic complexes,
and elucidate the governing orbital interactions.