Six-coordinate aluminium cations: characterization, catalysis, and theory

Gallium and indium complexes for ring-opening polymerization of cyclic ethers, esters and carbonates

“…In 1992, Olah et al first reported on the strong Lewis acid Ga(OTf) 3 being an effective catalyst for the bulk polymerization of THF at ambient temperature for the production of high-molecular-weight poly(THF) in excellent yield (Scheme 1) [6]. Such a Lewis-acidassisted ROP process likely proceeds via a cationic mechanism similar to that observed and studied by Atwood et al in the ROP of propylene oxide initiated by salen-Al-type cationic species [7].…”

Five-coordinate organoaluminum acetylides and crystal structure of the hydrosylate, [Salophen(tBu)Al]2O

“…Some of these can act as precursors to six-coordinate cations [14]. Beyond their fundamental interest and novelty, these high coordinate Salen-main group compounds are finding applications in catalysis [15][16][17]. For example, the asymmetric addition of diorgano-H-phosphonates to carbonyls (the phospho-aldol reaction) has been found to be catalyzed by chiral complexes of aluminum containing the salycen ligand framework, [(R,R)-Salcyen]AlX (X ¼ Me, OSiMe 2 t Bu) [17].…”

Synthesis, Characterization and Biological Activity of Schiff Base Metal Complexes Derived from 2, 4-Dihydroxyactophenone

“…A band at 1660 cm -1 in free Schiff base is due to the stretching vibration of azomethine [νC=N]. The shifting of this group to lower frequency (1627-1688 cm -1 ) in the metal complexes when compared to free ligand, suggests the coordination of metal ion through nitrogen of azomethine group 13 . New bands, which are not present in the ( Figure 3) spectrum of ligand, appeared in the spectra of complexes in the range of 727-767 cm -1, corresponding to νM-N and 623-662 cm -1 to νM-O vibrations respectively.…”