Heterometallic Second-Row Transition Metal Chain Compounds in Two Charge States: Syntheses, Properties, and Electronic Structures of [Mo-Mo-Ru](6+/7+) Chains.

Reaction of Mo2(dpa)4 (dpa = 2,2'-dipyridylamido) with (1)/2 equiv of [Ru(CO)3Cl2]2 in molten naphthalene at 250 °C provides facile access to the first all-second-row transition metal heterometallic chain compound, MoMoRu(dpa)4Cl2 (1). The one-electron oxidized compound [MoMoRu(dpa)4Cl2](OTf) (2) is synthesized by reaction of 1 with FeCp2(OTf). X-ray crystallography reveals a contraction of the Mo-Ru bond distance from 2.38 Å in 1 to 2.30 Å in 2, and an elongation of the Mo-Mo bond distance from 2.12 Å in 1 to 2.21 Å in 2. The short Mo-Ru bond distances indicate significant electron delocalization along the Mo-Mo-Ru chain, which is quantified by density functional theory (DFT) calculations. Molecular orbital analyses of both compounds based on DFT results reveal full delocalization of the orbitals of σ and π symmetry for both compounds. Additionally, δ orbital delocalization is observed in 2.