Microwave‐Assisted Generation of Lanthanide(II) Halides in THF and Simple Quantitative Determination

Abstract

Lanthanide(II) reagents (SmI2, SmBr2, YbI2, EuI2) have been prepared rapidly in high yields using microwave‐assisted heating. Samarium diiodide is obtained as a saturated solution in THF (0.13 M) within 5 min and ytterbium diiodide (0.065 M) after 45 min. A simple method for quantitative determination of LnX2 in THF is also described by utilizing the instantaneous reaction with ketones in the presence of an amine and water. This method establishes the concentration of the active single‐electron‐donor species, i.e. Ln2+. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Mechanistic Studies of Proton‐Donor Coordination to Samarium Diiodide

“…The concentration of SmI 2 was determined by iodometric titration or by the method developed by Hilmersson. [17] Benzyl bromide, dg, dgme, and dgde were dried over activated molecular sieves. Dried solvents and reagents were stored in an Innovative Technology, Inc. drybox containing an argon atmosphere and a platinum catalyst for drying.…”

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

“…(5)]. [13] However, perhaps the most convenient method of synthesis of SmBr 2 was reported by Flowers and coworkers who utilized readily available SmI 2 and LiBr [Scheme 2, Eq. (1)].…”

“…[97] On the basis of kinetic studies, the mechanism involving two SETs from europium(II) has been proposed. Perhaps the most intriguing aspect of this work is that nicotinic and picolinic acids [97b] as well as dialkylketones [13] were shown to be unreactive towards europium(II), thus showing the potential for chemoselective reductions. Furthermore, it is worth noting that both YbI 2 and EuI 2 provide important entry points to organometallic complexes of ytterbium and europium with downstream applications in inorganic chemistry, catalysis and polymerization.…”

Exploring SmBr2‐, SmI2‐, and YbI2‐Mediated Reactions Assisted by Microwave Irradiation

“…Altogether this makes these reactions less attractive with respect to large-scale syntheses. Previously, we have reported that SmI 2 and particularly SmBr 2 can be generated as suspensions in THF, [6] thus requiring a smaller volume of THF. The use of smaller volumes of solvent in reduction reactions is important as it allows reduction reactions to be carried out on a larger scale in smaller reaction vessels.…”