Isolation and Structural Characterization of a Binuclear Intermediate Species Pertinent to Transmetalation of Zn(salphen) Complexes and the Formation of Polynuclear Salen Structures

Abstract

Zinc(II) salphen complexes equipped with additional alkoxy donor groups at the 3-position of the salicylideneimine groups have been prepared to bind metal acetates in a second coordination sphere close to the central Zn(II) ion. The isolated binuclear monosalphen complexes have been studied in detail using NMR and MS techniques. Further synthesis has revealed that the formation of binuclear species from the parent salphen ligands is dependent on the nature of the bridging group between the two salicylideneimine groups and is prevented by replacement of one of the alkoxy substituents for a bulky t-Bu group. One of the binuclear Zn2 complexes was crystallographically characterized and can be regarded as a structural model for the intermediate stage of the transmetalation of the central Zn(II) center within these dinuclear compounds by other metal acetate salts. Furthermore, the X-ray diffraction structure also relates well with some intermediate structural stages of the buildup of various polynuclear salen structures.

Chiral tetranuclear and dinuclear copper(ii) complexes for TEMPO-mediated aerobic oxidation of alcohols: are four metal centres better than two?

“…[26][27][28][29][30] Schiff base type ligands are excellent ligand candidates for high-nuclearity metallosupramolecular assemblies, in particular in cases where additional O-donor atoms have been introduced to the backbone of a Schiff base ligand scaffold. [31][32][33][34][35] In search of active multimetallic copper catalysts for the aerobic oxidation reactions, we are particularly interested in exploring the catalytic performance of multinuclear copper(II) complexes based on simple Schiff base-type N,O-ligands. Although a dinuclear Cu II -N,O complex has been reported to catalyse the aerobic oxidation of primary alcohols and carbohydrates several years ago, suggesting the great potential of multimetallic copper complexes in catalytic alcohol oxidations, the structures of the catalyst species were not elucidated.…”

Unique tetranuclear heterometallic compound [Na2Zn2{(4-py)C(H)(NOH)}2(CH3COO)6(H2O)4].2H2O with luminescent properties

“…The acetate anion as a polydentate ligand is widely used in coordination chemistry nowadays. The generalization of modes of CH 3 COO − inclusion in coordination compounds is available [24][25][26][27][28][29][30][31][32][33]. Our search of CSD [34] revealed the commonly observed modes of the acetate anion coordination to the Zn(II) atom summarized in Scheme 2.…”

{4,4′-Dibromo-6,6′-dimethoxy-2,2′-[1,2-phenylenebis(nitrilomethanylylidene)]-κ4O1,N,N′,O1′}nickel(II)

“…The molecular structure of the title complex is shown in Figure 1 (Wang et al, 1994;Bhattacharya et al, 2011;Yu et al, 2009;Kargar et al, 2009;Felices et al, 2009). …”