Two Types of Heterometallic One-Dimensional Alignment Composed of Acetamidate-Bridged Dirhodium and Pivalamidate-Bridged Diplatinum Complexes

Two types of heterometallic one-dimensional chains, [{Rh2(acam)4}­{Pt2(piam)2(NH3)4}2] n ­(CF3SO3)4n ·2nMeOH (2, where acam = acetamidate, piam = pivalamidate) and [{Rh2(acam)4}­{Pt2(piam)2(NH3)4}] n ­(CF3CO2)2n ·2nEtOH (3), have been synthesized and characterized by single-crystal X-ray analyses. The chain structures in 2 and 3 are composed of two kinds of dinuclear complexes, [Rh2(acam)4] (i.e., [Rh2]) and [Pt2(piam)2(NH3)4] (i.e., [Pt2]), where Rh and Pt atoms are axially linked by metal–metal bonds. In 2 and 3, each complex is one-dimensionally aligned as −{[Rh2]–[Pt2]–[Pt2]} n – or −{[Rh2]–[Pt2]} n –, respectively, in which different alignments are caused by different isomers of [Pt2] that are HH (head–head) and HT (head–tail) orientation of piam ligands and their hydrogen bonding modes. Considering the crystal structures and X-ray photoelectron spectra (XPS) measurements in 2 and 3, the oxidation states of the metal atoms are −{[Rh2 II,II]–[Pt2 II,II]–[Pt2 II,II]} n – and −{[Rh2 II,II]–[Pt2 II,II]} n –, which are unchanged from those in the starting compounds. The diffuse reflectance spectra show that LUMOs are M–M σ-type orbitals. The gap between filled and vacant σ-type orbitals in 3 is narrower than that in 2, and is attributed to the relative higher destabilized filled σ-type orbitals caused by lower numbers of linking platinum atoms.