The electronic structures of a series of so-called "low-valent" transition metal complexes [M(mebpy)(3)](0) and [M(tPY)(2)](0) ((Me)bpy = 4,4'-dimethyl-2,2'-bipyridine and tpy = 2,2',6',2"-terpyridine) have been determined using a combination of X-ray crystallography, magnetochemistry, and UV-vis-NIR spectroscopy. More specifically, the crystal structures of the long-known complexes [Ti-IV(tpy(2-))(2)](0) (S = 0, 6), [V-IV(tpy(2-))(2)](0) (s = 1/2, 7), [Ti-III((Me)bpy.)(3)](0) (s = 0, 1), [V-II((Me)bpy.)(2)((Me)bpy(0))](0) (S = 1/2, 2), and [Mo-III((Me)bpy)(3)](0) (S = 0, 4) have been determined for the first time. In all cases, the experimental results confirm the electronic structure assignments that we ourselves have recently proposed. Additionally, the six-coordinate complex [Mo-III(bpy(0))(2)Cl-2]Cl center dot 2.5CH(3)OH (S = 3/2, 13), and seven-coordinate species [Mo-IV F-((Me)bpy.)2((Me)bpy(0))](PF6) (S = 0, 5), [(MoCl)-Cl-IV(tpy(0))(2)](PF6)center dot CH2Cl2 (S = 0, 11), and [(WF)-F-V(ty.r)(tpy(2-))](PF6).CH2Cl2 (S = 0, 12) have been synthesized and, for the first time, crystallographically characterized. Using the resulting data, plus that from previously published high-resolution X-ray structures of analogous compounds, it is shown that there is a linear correlation between the average C-PY-C'(PY) bond distances in these complexes and the total charge (n) of the ligands, {(bpy)(3)}(n) and {(tpy)(2)}(n). Hence, an assignment of the total charge of coordinated bpy or tpy ligands and, by extension, the oxidation state of the central metal ion can reliably be made on the basis of X-ray crystallography alone. In this study, the oxidation states of the metal ions range from +II to +V and in no case has an oxidation state of zero been validated. It is, therefore, highly misleading to use the term "low-valent" to describe any of the aforementioned neutral complexes.