Super‐Bulky Penta‐arylcyclopentadienyl Ligands: Elixir for the Isolation of the Full‐range of Half‐sandwich Heavy Alkaline‐earth Metal Hydrides

Hydrogenolysis of the half‐sandwich penta‐arylcyclopentadienyl supported heavy alkaline‐earth metal alkyl complexes (CpAr)Ae[CH(SiMe3)2](S) (CpAr = C5Ar5, Ar = 3,5‐iPr2‐C6H3; S = THF or DABCO) in hexane afforded the calcium, strontium and barium metal hydride complexes as the same dimers [(CpAr)Ae(μ‐H)(S)]2 (Ae = Ca, S = THF, 2‐Ca; Ae = Sr, Ba, S = DABCO, 4‐Ae), which were characterized by NMR spectroscopy and single‐crystal X‐ray analysis. 2‐Ca, 4‐Sr and 4‐Ba catalyzed alkene hydrogenation under mild conditions (30 oC, 6 atm, 5 mol% cat.), with the activity increasing with the metal size. A variety of activated alkenes including tri‐ and tetra‐substituted olefins, semi‐activated alkene (Me3SiCH=CH2), and unactivated terminal alkene (1‐hexane) were evaluated.

from A via a.sfakia on Inoreader http://bit.ly/2sHKVYU