The 1,8-naphthyridine-based (NP-based) ligands with furyl, thiazolyl, pyridyl, and pyrrolyl attachments at the 2-position have been synthesized. Reactions of 3-MeNP ( 3-methyl-1,8-naphthyridine), fuNP ( 2-(2-furyl)-1,8-naphthyridine), tzNP ( 2-(2-thiazolyl)-1,8-naphthyridine), pyNP ( 2-( 2- pyridyl)-1,8-naphthyridine), and prNP(-1) ( 2-( 2- pyrrolyl)-1,8-naphthyridine) with [Ru-2(CO)(4)( CH3CN)(6)](2+) lead to [Ru-2(3-MeNP)(2)(CO)(4)(OTf)(2)] ( 1), [Ru-2(fuNP)(2)(CO)(4)](2)[BF4](2) ( 2), [ Ru2( tzNP)(2)(CO)(4)][ClO4](2) (3), [Ru-2(pyNP)(2)(CO)(4)][OTf] (2) (4), and [Ru-2(prNP)(2)(CO)(4)] (5). The molecular structures of complexes 1-5 have been established by X-ray crystallographic studies. The modulation of the Ru-Ru single-bond distances with axial donors triflates, furyls, thiazolyls, pyridyls, and pyrrolyls has been examined. A small and gradual increase in the Ru-Ru distance is measured with various donors of increasing strengths. The shortest Ru-Ru distance of 2.6071( 9) angstrom is observed for the axially coordinated triflates in complex 1, and the longest Ru-Ru distance of 2.6969(10) angstrom is measured for axial pyrrolyls in complex 5. The Ru-Ru distances in complexes 3 ( 2.6734( 7) angstrom) and 4 ( 2.6792( 9) angstrom), having thiazolyls and pyridyls at axial sites respectively, are similar. The Ru-Ru distance for axial furyls in complex 2 ( 2.6261( 9) angstrom) is significantly shorter than the corresponding distances in 3, 4, and 5. DFT calculations provide insight into the interaction of the Ru-Ru sigma orbital with axial donors. The Ru-Ru sigma orbital is elevated to a higher energy because of the interaction with axial lone pairs. The degree of destabilization depends on the nature of axial ligands: the stronger the ligand, higher the elevation of Ru-Ru sigma orbital. The lengthening of Ru-Ru distances with respect to the axial donors in compounds 1-5 follows along the direction pyrrolyl > pyridyl approximate to thiazolyl > furyl > triflate, and the trend correlates well with the computed destabilization of the Ru-Ru sigma orbitals.