Group 13 Compounds Incorporating Salen Ligands

Abstract

In a previous review it was predicted that "the reactivity of five-coordinate complexes would certainly be different than that of the four-coordinate derivatives". Structurally and spectroscopically, there is very little difference in the higher-coordinate compounds when compared to the four-coordinate derivatives. However, the prediction was remarkably accurate, if not a bit understated, for the reactivity of these compounds. There appears to be a tremendous potential in catalysis and synthesis for the five-coordinate derivatives, far more possibilities than exist for the lower-coordinate derivatives. Furthermore, the higher-coordinate derivatives are rarely air or moisture sensitive and, thus, may be handled under a wider range of conditions. Although reactions such as oxirane and lactide polymerizations are fairly well-known now with five- and six-coordinate aluminum compounds, the potential of these compounds has only begun to be developed. It is easy to imagine that these types of compounds will see wider use than the related transition-metal compounds.

Five‐coordinated active species in the stereoselective polymerization of rac‐lactide using N,N′‐(2,2‐dimethyl‐1,3‐propylene) bis(3,5‐di‐tert‐butyl‐salicylideneimine) aluminum complexes

“…In general, the 27 Al NMR shifts move generally more downfield on passing from six-to five-and four-coordinated aluminum atoms. [30][31][32] The six-coordinate aluminum in Salen Al complexes has a chemical shift centered at d * 0 ppm, five-coordinate at d * 40 ppm, and four-coordinate at d * 70 ppm. 17 In the 27 13 These confirm that all of the three Al complexes, including LAlEt, LAlO i Pr, and the The kinetics of the polymerization was of first order in the concentration of rac-LA (Fig.…”

1,3-Bis[(4-methylbenzylidene)aminooxy]propane

“…Much interest has been focused on bisoxime compounds, in which the large electronegativity of O atoms is expected to affect strongly the electronic properties of the nitrogen atoms, and exhibit high stability against imine metathesis reactions ( Akine et al, 2005). Some of them or their metal complexes are used in wide field due to their variety of applications, especially for catalysis and biological processes, magnetism, and supramolecular architectures (Atwood et al, 2001;Yeap et al, 2008;Dong et al, 2008). Herein, the synthesis and structure of 4,4′-dimethyl-1,3-[propenedioxybis(nitrilomethylidyne)]dibenzene (I) is reported ( Fig.…”

“…For bisoximes and their applications, see: Akine et al (2005); Atwood & Harvey (2001); Dong et al (2008Dong et al ( , 2009; He et al (2008); Yeap et al (2008).…”

Crystal Structure of N,N'-Bis(4-trifluoromethoxybenzylidene)ethylenediamine

“…1,2 This interest is still growing, and considerable research effort has been devoted to the synthesis of new ligands and their complexes. 3,4 Schiff bases and their biologically active complexes have often been used as chelating ligands in the coordination chemistry of transition metals as radiopharmaceuticals for cancer targeting, agrochemicals, as model systems for biological macromolecules, as catalysts and as dioxygen carriers. 5 Although a series of Schiff base and their complexes have been studied crystallographically, there are only a very limited number of reports about free Schiff bases in the literature.…”

“…A synchrotron X-ray radiation was thus required to generate a sufficiently strong diffracted intensity for their characterization by single-crystal diffraction analysis. An attempt using synchrotron data obtained using a 0.10 × 0.10 × 0.04 mm 3 crystal with the Bruker APEX2 CCD diffractometer at the Daresbury Synchrotron Radiation Source (SRS) Light Source at Daresbury, UK was successful. The wavelength was fixed at 0.67270 Å.…”