Structural analysis of five-coordinate aluminium(salen) complexes and its relationship to their catalytic activity

Abstract

Five-coordinate aluminium(salen) complexes have dynamic structures which interconvert by intramolecular salen ligand rearrangement involving square-based pyramidal and trigonal bipyramidal conformations.

Octahedral Zirconium Salan Catalysts for Olefin Polymerization: Substituent and Solvent Effects on Structure and Dynamics

“…The higher values of δ N can be attributed to the switch of N from trans to solvent (as in * 3 + FF ) to trans to oxygen. The values of δ N′ , instead, suggest that this atom could be in an intermediate situation, somewhere between trans to benzyl (as in * 3 + FF ) and trans to oxygen; both MM and FM limiting geometries (Scheme ) could contribute to the actual structure of cationic complex * 4H + MM in solution and, on average, the actual geometry may be described as a distorted trigonal bipyramid having the N and O′ arms in the apical positions. , …”

“…The values of δ N′ , instead, suggest that this atom could be in an intermediate situation, somewhere between trans to benzyl (as in *3 + FF ) and trans to oxygen; both MM and FM limiting geometries (Scheme 3) could contribute to the actual structure of cationic complex *4H + MM in solution and, on average, the actual geometry may be described as a distorted trigonal bipyramid having the N and O′ arms in the apical positions. 31,51 Alternatively, the actual geometry might be so distorted that limiting "ideal geometries" are a bad fit. Importantly, 15 N NMR data trends suggest substantial structural modifications on passing from *4H + to *4H + -THF and *4H + -Lut (Table 2 and Supporting Information).…”

Aluminum Salen Complexes Modified with Unsaturated Alcohol: Synthesis, Characterization, and Their Activity towards Ring-Opening Polymerization of ε-Caprolactone and D,L-Lactide

“…The molecular structure of complex 3c is given in Figure 1 (see Supporting Information, Table S1 for crystallographic information). In general, complex 3c is not planar and has a bowl [ 4 , 8 ] conformation, where aryl rings are bent. Complex 3c in a solid state is monomeric due to the presence of bulky tert -butyl groups (compare with dimeric methoxy substituted complexes, [(Salen)Al(μ-OMe)] 2 [ 90 ] or [(MeSalen)Al(μ-OMe)] 2 [ 91 ]).…”

“…Aluminum alkoxides, due to their low toxicity, high Lewis acidity, wide abundance, and low cost, find application in chemistry, material science, and related fields of science. Examples are numerous catalysts in organic synthesis [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], the activation of small molecules (such as carbon dioxide) [ 8 , 9 , 10 , 11 ], description of the synthesis of complexes with unusual structures [ 12 , 13 ], precursors for sol-gel technology [ 14 ] or OLED and optic materials [ 15 , 16 , 17 ] based on Al compounds. At the same time, there are many works concerning the application of aluminum alkoxides based on different ligands as initiators [ 18 , 19 , 20 , 21 , 22 , 23 ] in ring-opening polymerization (ROP) [ 24 , 25 , 26 , 27 , 28 ] of lactones and lactide for the synthesis of biodegradable polymers.…”

Construction of novel hexanuclear Co(II) and dinuclear Ni(II) bis(salamo)‐type complexes

“…There has been considerable interest in multinuclear selfassemblies [5][6][7][8] designed and synthesized by transition metal ions and organic ligands. [9][10][11][12][13][14] In addition, the general strategy for designing multinuclear complexes is to use ligands in two coordination environments, which may exhibit different coordination modes with metals. [15][16][17][18][19][20] High-nuclear metal nanoclusters have attracted much attention due to their beautiful geometric configuration, special physicochemical properties, and luminescent materials.…”