Iminoacylberyllium Compounds Derived from Octamethyl- and Decamethylberyllocene and 2,6-Dimethylphenyl Isocyanide. Evidence for the Existence of η⁵/η¹Isomers of Beryllocenes

Abstract

The existence in solution of η 5 /η 1 isomers of the beryllocenes Be(C 5 Me 5 ) 2 and Be(C 5 Me 4 H) 2 is inferred from the results of their reaction with CNXyl to give iminoacyl products. The process is reversible and involves coupling of a Be-η 1 -Cp′ group with the isocyanide.

Synthesis, Solid-State Structures, and Computational Studies of Half-Sandwich Cp*BeX (X = Cl, Br, I) Compounds

“…The 13 C NMR spectra of 1 – 3 each show a single resonance for the ring carbon atoms (109.95 pm for 1 , 110.21 pm for 2 , and 110.53 pm for 3 in C 6 D 6 ), indicating η 5 -bonded Cp* groups. Comparable findings were reported for homo- and heteroleptic η 5 -Cp*BeX compounds such as Cp* 2 Be (110.4 ppm), Cp*BeCp (108.6 ppm), Cp*BeCl (109.6 ppm), Cp*BeMe (108.0 ppm), Cp*BeCp′ (108.9 ppm), Cp*BeCNXylCp* (108.8 ppm), and Cp*BeP­( t -Bu) 2 and Cp*BeAs­( t -Bu) 2 (109.3 ppm) . In addition, 9 Be­{ 1 H} NMR spectra (Table ) gave resonances at −14.9 ppm for 1 , −14.8 ppm for 2 , and −15.8 ppm for 3 , which compare well with values reported for Cp* 2 Be (−21.7 ppm, w 1/2 = 4.4 Hz) , and Cp*BeCp′ (−19.7 ppm, w 1/2 = 4.4 Hz) and clearly show the η 5 coordination mode of the Cp* ligand.…”

Cyclopentadienyl Complexes of the Alkaline Earths in Light of the Periodic Trends

“…[Cp*Be{B( Dipp DAB)}] has a Be‐B bond [78] . [Cp* 2 Be], [Cp Me4 2 Be], and [Cp*BeCp Me4 ] all undergo reversible isonitrile insertion with CN(Xyl) [19b,79] . The last two give temperature‐dependent positional isomers due to the fluxional behavior.…”

Alkaline Earth Organometallics

“…59 The process is reversible with 10 (DH ¼ 18 AE 0.4 kcal mol À1 ; DS ¼ 35 AE 1 cal mol À1 K À1 ), and the insertion product 15 obtained at 25 C was characterized with X-ray diffraction ( Figure 7). 59 The process is reversible with 10 (DH ¼ 18 AE 0.4 kcal mol À1 ; DS ¼ 35 AE 1 cal mol À1 K À1 ), and the insertion product 15 obtained at 25 C was characterized with X-ray diffraction ( Figure 7).…”