; Reported herein is a series of Ru-2(Xap)(4) capped polyyn-diyl compounds, where Xap is either 2-anilinopyridinate (ap) or its aniline substituted derivatives. Symmetric [Ru-2(Xap)(4)](mu-C-4k)[Ru-2(Xap)(4)] (compounds 4ka (X = 3-isobutoxy) and 4kc (X = 3,5-dimethoxy) with k = 2, 3, 4, and 5) was obtained from the Glaser coupling reaction of Ru-2(Xap)(4)(C2kH). Unsymmetric [Ru-2(Xap)(4)](mu-C4k+2)[Ru-2(ap)(4)] (compounds 4k4-2b with k = 2, 3, and 4) were prepared from the Glaser coupling reaction between Ru-2(Xap)(4)(C2k+2H) and Ru-2(ap)(4)(C2kH). X-ray diffraction study of compound 12c revealed both the sigmoidal topology of the polyyndiyl bridge and the fine structural detail about the Ru-2 cores. Cyclic and differential pulse voltammetric (CV and DPV) measurements and spectroelectrochemical studies revealed that (i) the reduced monoanions [Ru-2-C2-mRu2](-1) (m = 4-8) belong to the Robin-Day class II mixed valent ions and (ii) the electronic coupling between Ru-2 termini depends on the length of the polyyn-diyl bridge with an attenuation constant (gamma) between 0.12 and 0.15 angstrom(-1). In addition, spin-unrestricted DFT calculations provide insight about the nature of orbitals that mediate the long distance electronic coupling.