Schiff bases salicylaldehyde diamines

The complexes with Schiff bases (SBs) derived from diamines and salicylaldehydes (66) or /3-diketones (67) normally have a 1 1 stoichiometry. 

Although complexes with these ligands are common in palladium(II) chemistry, their occurrence is more scarce in platinum(II) compounds. Nevertheless these complexes can be prepared, examples being platinum(II) complexes of the optically active quadridentate Schiff base of salicylaldehyde and (R)-l, 2-diamines.1212 An alternative synthesis involves formation of the Schiff base by reaction of a complexed amino ligand on platinum(II) with amide acetates (equation 372).1213... 

Measurement of stability constants for complex formation between Zn2+ and the Schiff bases derived from salicylaldehyde (sal) and either en or 1,3-diaminopropane indicate terdentate coordination by two nitrogen atoms and one oxygen atom. Zn2+ also promotes formation of these Schiff bases, and the rate constants are consistent with a mechanism which involves the preequilibrium formation of a mixed [(sal)Zn(diamine)]+ complex.1216... 

The first production of polymer N202-chelates starts from a macroporous glycidyl methacrylate-ethylene dimethycrylate copolymer Nucleophilic addition of ethylen-diamine led to polymer amine, which is converted with salicylaldehyde to the Schiff base ligand (57) and then with Cu and Co to chelates (52) (Eq.20). 

Schiff-base ligands prepared form the condensation of salicylaldehyde with diamines offer [N2O2] donor sets that are capable of coordinating a wide range of metals. Tin(IV) acetate reacts with salenH2 and R2SnCl2 reacts with either (3-MeO)salphen (R = Ph, Bu , or the ligand... 

Imine bases (Schiff bases) such as bis(salicylaldehyde)ethylene diamine (salen)... 

The synthesis of a variety of dibenzodiaza-crowns from salicylaldehyde or its derivatives has been reported by Lindoy and coworkers (Adam et al., 1981a, 1981b Armstrong and Lindoy, 1975 Armstrong et al., 1977 Baldwin et al., 1987 Grimsley et al., 1977). The macrocycles were obtained via the corresponding diimines (Schiff bases), which were obtained by condensations of the appropriate dialdehydes and diamines as shown (method U-14). It was... 

The Co(SALEN) complexes are attractive organocobalt-model complexes due to their ready preparation via Schiff-base condensation of a diamine and o-salicylaldehyde, (3). The limitation of these resultant species is the N2O2 ligand field, rather than the desired N4 donor. Variations of the condensation protocol have resulted in the preparation of related complexes suitable for organocobalt synthesis. 

Schiff base) and UO dl), 197 with 3,3 -methylenebis-(5-chlorosalicylaldehyde (Schiff base) and UOjdl), 197 with 5,5 -methylenebis-(salicylaldehyde) and Cd, Co, Cu(ll), Fe, Ni, orZn, 198 p-Phenylene diamine... 

The general term Salen-type is used in literature to describe the class of [O, N, N, O] tetradentate bis-Schiff base ligands. Some of the salen ligands 167,168 and 169 and their metal complexes are illustrated in Fig. 9.9. Commercial synthesis of chiral Salen complex 171, from chiral diamine salt 172 and salicylaldehyde derivative 173 is presented in Scheme 9.45 [83]. 

Due to their similarity to porphyrins and their ease of synthesis, Schiff bases have been extensively explored as ligands in oxidation catalysis [38, 44, 45]. Salen-type Hgands are the most commonly used class of Schiff bases, and are synthesized from a diamine and two equivalents of a salicylaldehyde in which chiral derivatives are readily accessed (Fig. 5.5) [46]. Additionally, Schiff base ligands coordinate and stabilize a diverse range of metals in various oxidation states making them an excellent template to explore direct 02-coupled catalytic oxidations. 

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