Structures, electronic configurations, and magnetic interactions of heterometallic one-dimensional chains

Abstract One-dimensional coordination networks connected through halide ions or organic linkers have been frequently described, but examples featuring direct metal–metal bonding remain scarce and are mainly limited to rhodium, palladium, iridium, and platinum. Here, we report a series of one-dimensional heterometallic complexes in which two or three metal centers are regularly arranged through metal–metal bonds, facilitated by interactions between the highest occupied molecular orbital (HOMO–) and the lowest unoccupied molecular orbital LUMO involving the σ* orbitals of two different precursors. The resulting single crystals are vividly colored with a metallic sheen. Unlike the typical HOMO of homometallic one-dimensional chains (a partially oxidized σ-type orbital), the HOMO of the heterometallic analogs is an additional metal-derived orbital inserted between the σ-type valence and conduction bands. This unique orbital arrangement confers magnetic behavior and tunable electronic properties. We further demonstrate strong magnetic coupling mediated by direct metal–metal interactions in these systems.