A General High-Yield Route to Bis(salicylaldimine) Zinc(II) Complexes:  Application to the Synthesis of Pyridine-Modified Salen-Type Zinc(II) Complexes

Abstract

A general, direct, and high-yield synthesis of bis(salicylaldimine) zinc complexes from the ligands and Et(2)Zn is reported. This synthetic method is particularly valuable, not only because it allows the efficient preparation of salen-type complexes of zinc but also because it can be used to prepare bifunctional pyridine-modified zinc(II) bis(salicylidene) complexes, which are potentially useful compounds for applications in asymmetric catalysis and materials chemistry. The synthesis and complete structural characterization of a new series of pyridine-modified zinc(II) bis(salicylidene) ligands is discussed.

X‐ray Crystal Structure and Characterization in Aqueous Solution of{N,N′‐Ethylenebis(pyridoxylaminato)}zinc(II)

“…Their low solubility in most common solvents is another drawback, and only a few complexes have been characterized by X-ray diffraction. The Zn II ion in these complexes is either fivecoordinate with a square-pyramidal geometry [6,7] or has a dinuclear structure. [8] Singer et al [6] have characterized two mononuclear zinc complexes with sal 2 en-type SB's (SB = Schiff base) containing a solvent molecule in a fifth coordi- nation position.…”

Enantioselective phenylacetylene addition to aldehydes and ketones catalyzed by recyclable polymeric Zn(salen) complex

“…41 Charac- The interesting feature of this novel polymeric Zn salen complex is its inherent tendency to be precipitated out in nonpolar solvent like hexane due to its higher molecular weight and lower solubility in reaction medium. We have recovered the catalyst, which worked well up to four cycles with gradual loss in reactivity due to physical loss during post work up process but with retention of enantioselectivity of propargylic alcohols (Table 5).…”

New Helical Zinc Complexes with Schiff Base Derivatives of β‐Diketonates or β‐Keto Esters and Ethylenediamine

“…Metal amides (third route) or alkyls (forth route) can also be used as initial reagents; the only by-products are volatile amines or alkanes. [11,14] Metal complexes with Schiff base derivatives of salicylic aldehyde can be also obtained by a two-step reaction including the deprotonation of the Schiff base with sodium-or potassium hydride followed by reaction with a metal halide (fifth route). The last three synthetic routes allow the obtainment of pure final products with high yields, but they are more complicated and have to be conducted under an inert atmosphere because of the high moisture sensitivity and reactivity of the initial reagents.…”