Das Bis(allyl)bismut‐Kation: ein Reagens für direkte Allyl‐ Übertragung und kontrollierte radikalische Polymerisation

Abstract

Das Plus an Effizienz: Das Bis(allyl)bismut‐Kation (siehe Struktur) in [Bi(C3H5)2(thf)2] [B(C6H3Cl2)4] erwies sich bei der Additiv‐freien Allylierung ungesättigter C‐Heteroatom‐Funktionen und bei der kontrollierten lebenden Radikalpolymerisation aktivierter Olefine dem neutralen Tris(allyl)bismut als überlegen.

Structurally Defined Allyl Compounds of Main Group Metals: Coordination and Reactivity

“… Ambient‐temperature 1 H NMR spectra of compounds containing a) η 1 ‐bonded allyl ligands (A 2 MNX; example: [Bi(C 3 H 5 ) 3 ]);109 b) η 3 ‐bonded allyl ligands (A 2 B 2 X; example: [K(C 3 H 5 )]);37d c) fluxional allyl ligands (A 4 X; example: [Mg(C 3 H 5 ) 2 ]);53 d) allyl ligands with a coordination behavior intermediate between (a) and (c) (example: [Ga(C 3 H 5 ) 3 (thf)]) 76. Integrals are set to values corresponding to one allyl ligand.…”

“…Low values for the activation entropy Δ S ≠ indicate an ordered transition state, but the interpretation in terms of the molecularity of the allyl exchange is controversial 80–82. 109 A third mechanism accounting for allyl exchange is the thermally induced suprafacial [1,3]‐sigmatropic rearrangement (Scheme ). It is relevant for semimetals and goes along with inversion of the stereocenter at M (if applicable).…”

“…The homoleptic allyl compounds of Group 15 with the general formula [M(C 3 H 5 ) 3 ] (M=As,106 Sb,107 Bi)108, 109, 110c are distillable liquids used for metalorganic chemical vapor deposition and related processes (see Section 5.5) 110. The main decomposition pathway is the coupling of allyl ligands to give 1,5‐hexadiene with concomitant formation of M 0 109. 110b The allyl ligands show an η 1 bonding mode in the liquid phase94, 106, 109 and a weak β effect has been suggested for derivatives of As and Sb (see Section 4.5) 111.…”

“…The main decomposition pathway is the coupling of allyl ligands to give 1,5‐hexadiene with concomitant formation of M 0 109. 110b The allyl ligands show an η 1 bonding mode in the liquid phase94, 106, 109 and a weak β effect has been suggested for derivatives of As and Sb (see Section 4.5) 111. A dynamic behavior of the allyl ligands has not been reported for the homoleptic compounds, although high‐temperature scenarios have not been investigated.…”

“…Such compounds with the Group 15 fragment at the less‐substituted terminus of the allylic system are the thermodynamically more‐stable isomers 111. In halogenated or cationic derivatives of allyl bismuth, [Bi(C 3 H 5 ) 2 (I)] and [Bi(C 3 H 5 ) 2 (thf) 2 ] + , the allyl ligands show dynamic behavior in solution 109. In the latter case, an intramolecular mechanism has been suggested on the basis of the activation entropy being significantly higher than in intermolecular allyl‐exchange processes.…”