Über die erstmalige Darstellung des Lithium‐Tris‐2, 2′‐Dipyridyl‐Niob(‐1) Li[NbDipy₃] · 3,5 THE

Electronic Structures of Homoleptic [Tris(2,2′-bipyridine)M]nComplexes of the Early Transition Metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta;n= 1+, 0, 1–, 2–, 3−): An Experimental and Density Functional Theoretical Study

“…It has not been possible to isolate the corresponding salt of the anionic species [Nb( t bpy) 3 ] 1-, but the unsubstituted [Nb(bpy) 3 ] 1complex is already known. 17 The electronic spectra of the neutral complexes [M( t bpy) 3 ] 0 (M = V, 21b Nb, Ta) are presented in Figure 1 and summarized in Table 4 alongside data for [Ti III (bpy • ) 3 ] 0 and [Cr( t bpy • ) 3 ] 0 .…”

“…Oxidation of the monoanion [Ta( t bpy) 3 ] 1‑ by 1 equiv of tropylium tetrafluoroborate in THF yields the clean, neutral complex [Ta( t bpy) 3 ] 0 in very good yields. It has not been possible to isolate the corresponding salt of the anionic species [Nb( t bpy) 3 ] 1‑ , but the unsubstituted [Nb(bpy) 3 ] 1‑ complex is already known …”

“…The corresponding unsubstituted species [M(bpy) 3 ] 0 (M = Nb, Ta) also possess an S = 1 / 2 ground state . In contrast, both [Na(THF) 5 ][Ta( t bpy) 3 ] and Li[Nb(bpy) 3 ]·3.5THF are diamagnetic. Whereas the EPR spectrum of [Nb( t bpy) 3 ] 0 was recorded in THF solution at ambient temperature (Figure a), that of [Ta( t bpy) 3 ] 0 was recorded as a powdered solid sample at 20 K (Figure b).…”

“…Early transition metal tris(2,2′-bipyridine) complexes (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with charges ranging from 1+ to 3–, accessible via successive one-electron transfer steps, have been generated either chemically or electrochemically, and in many instances isolated as neutral species or salts. , Table provides a list of the complexes isolated to date and their electronic ground states. − Despite the fact that many of the complexes shown in Table have been synthesized as early as the mid 1960s, in only a few cases have their electronic structures been elucidated spectroscopically (using UV–vis and EPR, and magnetochemically) and correctly described.…”