Water‐Soluble Cobalt(II) and Copper(II) Complexes of 3‐(5‐Chloro‐2‐hydroxy‐3‐sulfophenylhydrazo)pentane‐2,4‐dione as Building Blocks for 3D Supramolecular Networks and Catalysts for TEMPO‐Mediated Aerobic Oxidation of Benzylic Alcohols

Abstract

A new water-soluble β-diketone azo derivative Ϫ 3-(5-chloro-2-hydroxy-3-sulfophenylhydrazo)pentane-2,4-dione (H 3 L, 1) Ϫ was synthesized and found to be stable in DMSO solution and in the solid state in the hydrazo tautomeric form.

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

“…X-ray structure of (R)-1 with ellipsoids plotted at the 50% probability level, and H atoms and dichloromethane solvent omitted for clarity. Selected bond lengths: Cu1-O2 = 1.898(2), Cu1-O3 a = 1.936(2), Cu1-N1 = 1.937(2), Cu1-O1 = 1.9613 (19), Cu2-O4 = 1.869(2), Cu2-O3 = 1.903(2), Cu2-N2 = 1.919(2), Cu2-O1 = 1.9362(18) Å. Symmetry code: a = -x, y, -z. refined to 0.030 (9). The complete molecular cluster without the solvated dichloromethane is depicted in Fig.1 and relevant bond lengths given in the caption are unexceptional.…”

“…12-17 However, the types of organic ligands exploited in the copper catalyst systems are still limited and the structures of copper catalysts involved in the catalytic process are rarely explored. [17][18][19][20] The construction of metal-organic cluster compounds through self-assembly of predesigned ligands with appropriate metal ions is a prime research topic [21][22][23][24][25] Herein, we report the one-pot syntheses and crystal structures of two tetranuclear and dinuclear copper(II) complexes resulting from the in situ synthesis of chiral Schiff base ligands (Scheme 1), and their catalytic applications in the TEMPO-mediated aerobic oxidation of benzylic alcohols. The catalytic potential of two complexes is compared based on their catalytic performance in various alcohol oxidation reactions, suggesting that the copper(II) complex with a Cu 4 core is a more efficient catalyst than that one having a Cu 2 core.…”

“…[12][13][14][15][16][17] However, the types of organic ligands exploited in the copper catalyst systems are still limited and the structures of copper catalysts involved in the catalytic process are rarely explored. [17][18][19][20] The construction of metal-organic cluster compounds through self-assembly of predesigned ligands with appropriate metal ions is a prime research topic [21][22][23][24][25] due to the advantages in catalysing useful chemical transformations, in contrast to simple monometallic complexes. [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.…”

Water-soluble heterometallic copper(II)-sodium complex comprising arylhydrazone of barbituric acid as a ligand

“…The preparative procedures for these complexes are usually straightforward and can give high yields of the final products. Also it was demonstrated, that by modification of the methylene active moiety or by introduction of different substituents to the aromatic part of AHAMCs one can significantly change the nuclearity and overall topology of the formed complexes [1].Aquasolubility of the AHMACs and their complexes would be particularly important for green catalytic applications, pharmaceutical and other activities where water is an essential solvent or/and a reactant [1,4,14,15]. Introduction of a hydrophilic polar (e.g., sulfo-or nitro-) group into the ligand is one of the common ways to increase the water solubility of its complexes; moreover, the introduced moieties can behave as additional coordinating sites thus supporting an extension of coordination arrays in the solid state [1] and/or inducing the formation of heterometallic complexes [7].…”

“…For example, arylhydrazones of β-diketones contain a flexible O,N,O donor site which can chelate a number of metal ions, thus leading to Cu II [1][2][3][4][5][6][7], Zn II [8][9][10][11], Ni II [2,12], Na I [13], K I [7,12], Pb II [8], Cd II [9], Co II [14] complexes of different nuclearities and topologies. Moreover, the first example of an heterometallic Cu II -K AHAMC complex has been recently reported by some of us [7].…”