Theoretical Study of the Intrinsic Reactivities of Various Allylmetals toward Carbonyls and Water

Abstract

Quantum mechanics MP2/6-31+G* calculations have been carried out for the reactions of a series of monomeric allylmetals with water and carbonyl compounds in the gas phase. Allyl complexes of groups IA and IIA and low-valent group IIIA and IVA metals are π-complexes or reactive σ-complexes. They show high reactivities toward hydrolysis. Group IIB, trivalent group IIIA, tetravalent group IVA, and both tri-and pentavalent group VA metals form σ-complexes with allyl. These allylmetals are less reactive toward hydrolysis than toward allylation. The calculated intrinsic kinetic preference of allylation over hydrolysis is found to correlate well with the reactivity of hydrolysis, the nucleophilicity of the allylmetals, and the lateness of hydrolysis transition structures. Both the nucleophilicity of the allylmetal complexes and the thermodynamic driving force are important to the reactivity of hydrolysis. Importantly, there is a large thermodynamic preference for allylation over hydrolysis for all allylmetals because the hydrolysis has to break a strong O-H bond. Thus, the kinetic preference for allylation is correlated with the degree of H-O bond breaking in the hydrolysis transition structure.

Hybrid Porous Materials with High Surface Area Derived from Bromophenylethenyl‐Functionalized Cubic Siloxane‐Based Building Units

“…Whether the same situation applies to beryllium allyl compounds is not entirely clear, but π bonding would not normally be expected 26. Wu et al., for example, determined that the minimum energy structure of [(C 3 H 5 )BeBr] at the MP2//HF level of theory contains a σ‐bound allyl ligand 27. However, John and co‐workers computationally modeled the allyl ligand in the compound [(η 3 ‐C 3 H 5 )BeAs( t ‐Bu) 2 ], and found that a π‐bonded allyl group on beryllium was reasonable 23…”

Solvent-resistant structures of base-free lithium and potassium allyl complexes, M[(SiMe3)nC3H5-n] (M = Li,n= 3; M = K,n= 2)

“…roughly linear K(1)À ÀK(2)À ÀK(1) 0 sections (170.28) alternating with strongly bent K(2)À ÀK(1)À ÀK(2) 0 angles (103. 38)], but it is difficult to ascribe chemical significance to this, given the broader structural difference between the chains (helical vs. simple undulations). [33]), indicating the similarly ionic bonding in the complexes.…”

“…As befits its importance in the family of organolithium reagents, the relative stabilities and geometries of bridged (Z 3 -bound) and sigma-bonded (Z 1 -bound) allyllithium, and the influence of coordinated solvent on the structures and barriers to ligand rotation have been the subject of repeated computational studies [37,38]. The symmetrical p-bound form of Li(C 3 H 5 ) is well established as lower in energy than a ''classical'' s-bonded structure [39].…”

Aqueous Barbier Allylation of Aldehydes Mediated by Tin

“…Recently, Chan et al carried out a theoretical study of hydrolysis and carbonyl additions reactions for a series of allylmetals in gas phase [27]. The divalent metal allyl complexes of group 14 have similar reactivity toward hydrolysis and carbonyl addition.…”