Group 3 Metal Complexes of Radical-Anionic 2,2′-Bipyridyl Ligands

Abstract

A new method for generating group 3 metal complexes containing radical-anionic 2,2'-bipyridyl (bipy) ligands is described that relies on hydrogen-atom abstraction from dearomatized biheterocyclic complexes. This method does not involve electron transfer to neutral 2,2'-bipyridyl or salt metathesis between the lithium salt of the 2,2'-bipyridyl radical anion and group 3 metal halides. The new metal complexes were characterized by single-crystal X-ray diffraction, electron paramagnetic resonance, and absorption spectroscopy. Density functional theory (DFT) calculations were used to probe the electronic structure of these compounds. All these methods support the radical-anionic character of bipy in all bipy compounds presented.

Reactivity and Properties of Metal Complexes Enabled by Flexible and Redox-Active Ligands with a Ferrocene Backbone

“…43 In addition, the group 13 metal complex (salfen)In(OtBu) was prepared through salt metathesis between InCl 3 and K 2 (salfen) followed by treating (salfen)InCl with KOtBu, 38 while late transition metal complexes such as M(salfen) (M = Co, Zn) were also prepared by salt metathesis from the corresponding metal chlorides. 87 C. C-H Activation, Dearomatization, and Ring-Opening Reactions of aromatic N-heterocycles Scheme 3: Reactivity of rare-earth metal alkyl complexes supported by ferrocene diamide ligands toward aromatic N-heterocycles: (a) C-H activation of pyridine followed by C-C coupling and formation of bipyridine radical anion; 63 (b) dearomatization of isoquinoline; 65 (c) C-H activation of 2-phenylpyridine followed by hydrogen migration; 54 (d) ring-opening of 1-methylimidazole; 82 (e) reactivity of pincer-type pyridine diamide complexes. 67 Rare-earth metals are highly electropositive and can activate strong C-H bonds typically through a -bond metathesis mechanism.…”

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

“…The electron donating 1,1′-ferrocenediyl group (Sauro and Workentin, 2002) makes the amide donor bind strongly to the highly electropositive group 3 metals and uranium(IV) ion. By using NN TBS as the ancillary ligand for d 0 f n metal alkyl complexes, the C-H bond activation of aromatic heterocycles , successive C-C bond coupling Carver et al, 2010;Monreal and Diaconescu, 2010;Williams et al, 2010), dearomatization of aromatic heterocycles , and the unprecedented ring-opening of 1-methylimidazole Monreal et al, 2009), 1-methylbenzimidazole , or other aromatic heterocycles (Duhović et al, 2010) were observed and studied (Diaconescu, 2010a;Diaconescu, 2010b).…”

Analysis of Lanthanide-Radical Magnetic Interactions in Ce(III) 2,2′-Bipyridyl Complexes

“…However, whilst there have been numerous studies on complexes of the general formula [Ln(L) 2 (bipy •-)] (Ln = Eu, Sm, Yb; bipy = 2,2′-bipyridyl), [24][25][26][27][28][29][30]32,33 there are relatively few reports on analogous systems for lighter Ln centers. [44][45][46][47] Herein, we have thoroughly characterized a series of complexes of the general formula [Ln(Cp R ) 2 (bipy •-)] (Ln = La, Ce), examining their physical properties and reactivity, and probing the nature of 4f-electron/radical exchange interactions.…”