Schiff base type ligands

Iron(III) Spin Crossover Systems of Multidentate Schiff Base-Type Ligands 285... 

Abstract In this chapter, selected results obtained so far on Fe(III) spin crossover compounds are summarized and discussed. Fe(III) spin transition materials of ligands containing chalcogen donor atoms are considered with emphasis on those of M,f T-disubsti-tuted-dithiocarbamates, Ar,N-disubstituted-XY-carbamates (XY=SO, SSe, SeSe), X-xan-thates (X=0, S), monothio-/J-diketonates and X-semicarbazones (X=S, Se). In addition, attention is directed to Fe(III) spin crossover systems of multidentate Schiff base-type ligands. Examples of spin inter-conversion in Fe(III) compounds induced by light irradiation are given. 

Schiff base-type systems are the second most widespread class of ligands which have been used to obtain Fe(III) spin crossover materials. These ligands may be classified according to the number of donor atoms available for coordination to the Fe(III) ion. In Sects. 3.1 to 3.4 attention is drawn to tri-, tetra-, penta- and hexadentate Schiff base-type ligands, severally. Section 3.5 focuses on spin crossover in iron(III) induced by light irradiation, whereas Sect. 3.6 is devoted to recent developments in the field of materials science with the objective of incorporation of Fe(III) spin crossover materials in devices. 

The major breakthrough in this field was achieved in 2003 by Legros and Bolm [164], who reported a highly enantioselective iron-catalyzed asymmetric sulfide oxidation. Optically active sulfoxides were obtained with up to 96% ee in good yields under very simple reaction conditions using Fe(acac)3 as precatalyst in combination with a Schiff base-type ligand (Table 3.9). Furthermore, inexpensive and safe 35% aqueous hydrogen peroxide served as terminal oxidant. 

LIGATION OF ZEOLITE EXCHANGED TRANSITION IONS WITH SCHIFF BASE-TYPE LIGANDS... 

Many complexes have been prepared using Schiff-base-type ligands, which can be heptadentate and octadentate and give mononuclear or dinuclear complexes. ... 

Rare Earth Complexes with Schiff Base Type Ligands... 

Bandoli G, Mazzi U, Moresco A, Nicolini M, Refosco F, Tisato F (1986) Technetium complexes containing tridentate and bidentate Schiff base type ligands. In Nicolini M, Bandoli G, Mazzi U (eds) Technetium in chemistry and nuclear medicine 2. Cortina International, Verona, Italy, pp... 

Shamim and Paul (2010) found that the silica modified by a Schiff base-type ligand promoted the Cu-catalyzed, three-component synthesis of 1,2,3-triazoles in water at room temperature (Scheme 4.3). It also exhibited higher efficiency than Wang s promoter, probably because the Schiff bases possess much better coordinating ability than the primary amines. 

Jiang J-J, Huang J, Wang D, Yuan Z-L, Zhao M-X, Wang F-J, Shi M. Cu(I)-catalyzed asymmetric chlorination of (3-ketoesters in the presence of chiral phosphine-Schiff base type ligands. Chirality 2011 23(3) 272-276. 

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