Nucleophilic attack at the central allyl carbon atom in [(.eta.3-allyl)ML2]+ complexes (M = palladium, platinum). Experimental facts and new theoretical insights

Nucleophilic attack on η3-allyl and η2-tetrahydroborate complexes of ruthenium(ii)

“…The NMR data for all new ruthenium complexes and for adducts of BH 3 are collected in Table 1. Unless indicated otherwise, all 31 P, 13 C and 11 B data refer to spectra recorded with full proton decoupling. IR and elemental analysis data are given in the experimental section: IR data are limited to bands due to C-O stretching modes and those assigned to BH 4 Ϫ ligands.…”

“…The situation for complexes in which the organic ligand is "odd" (and in particular for the η 3 -allyl ligand) is less clear-cut, with examples of attack on both the terminal 5-7 and the central 7-11 carbon atoms. Although other groups 12, 13 have since suggested somewhat different theoretical approaches, it was originally proposed 4 that the site of attack on the allyl ligand was determined by the electronsupplying or -withdrawing nature of the rest of the complex, making a prediction for [Ru(CO) 2 (η 3 -C 3 H 5 )(PMe 2 Ph) 2 ] ϩ , which contains both predominantly σ-donor and π-acceptor ligands, particularly difficult. The reaction intended to produce the ruthenacyclobutane used BH 4 Ϫ as a source of hydride ion.…”

Advances in Palladium‐Catalyzed Decarboxylative Cycloadditions of Cyclic Carbonates, Carbamates and Lactones

“…In contrast, electron‐deficient ligands tended to produce the spirocyclic 2‐pyrrolidinone 164 f . These results could be attributed to that because the two empty n (non‐bonding) and π * (antibonding) orbitals of π ‐allyl palladium moiety are very close in energy level, [61b–d] electron‐deficient ligand would facilitate lowering the energy level of the π *‐derived empty orbital. Thus the π * orbitals overlapped well with the HOMO of the incoming nucleophile to produce the preferential formation of palladacyclobutane 4.1B (Scheme 78), delivering the spirocyclic 2‐pyrrolidinone 164 f after reductive elimination of the palladacyclobutane.…”

Transition Metal-Catalyzed Decarboxylative Allylation and Benzylation Reactions

“…To explain this, the authors proposed that the reactive orbitals on the allyl moiety (n and π* orbitals) are energetically similar and easily attenuated via choice of phosphine ligand. 137 In addition, stronger nucleophiles, like those derived from alkyl isocyanates, were suggested to have better orbital overlap with the central carbon leading to spiro[2.4]lactams (Scheme 63). 137b …”

“…137 In addition, stronger nucleophiles, like those derived from alkyl isocyanates, were suggested to have better orbital overlap with the central carbon leading to spiro[2.4]lactams (Scheme 63). 137b …”