Asymmetrical Platinum and Rhodium Dinuclear Complex Strongly Bound to Filled d z2 ${{_{{\rm z}{^{2}}}}}$ Complexes by Unbridged Pt−Metal Bonds: Toward Heterometallic‐Extended Metal Atom Chains

Heterometallic extended metal atom chains (EMACs) aligned with three types of metal were rationally synthesized by forming unbridged metal−metal bonds based on the interactions between highest occupied and lowest unoccupied molecular orbitals at the d z2 ${{_{{\rm z}{^{2}}}$ orbital. These chains form pentanuclear structures aligned as Rh−Pt−M−Pt−Rh with relatively large formation constants of 5.0×1013 M−2 for M=Pt and 6.3×1011 M−2 for M=Pd, while retaining their backbones in solution. In the case of M=Cu, the original Cu(+2) atoms were reduced to Cu(+1) during the synthetic process. Cu(+1) has an unprecedented trigonal bipyramidal coordination geometry. The reported synthesis based on asymmetrical dinuclear complexes provides a guideline for the synthesis of hetero‐EMACs to allow several analogs through judicious combinations realized by tuning the number of metal nuclei and metal species. Line up, line up! HOMO‐LUMO interactions between metal d z2 ${{_{{\rm z}{^{2}}}$ orbitals were used to synthesize hetero‐xtended metal atom chains (EMACs) for tuning the number of nuclei and metal species. Mixing an asymmetrical Pt−Rh dinuclear complex with a LUMO in the σ* orbital and a mononuclear complex with a HOMO in the d z2 ${{_{{\rm z}{^{2}}}$ orbital allows two‐step multinucleation, affording hetero‐EMACs with three well‐aligned metal species.