Copper(II) and Sodium(I) Complexes based on 3,7‐Diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide: Synthesis, Characterization, and Catalytic Activity

Abstract

The reaction of 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) with metal salts of Cu or Na /Ni under mild conditions led to the oxidized phosphane derivative 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane-5-oxide (DAPTA=O) and to the first examples of metal complexes based on the DAPTA=O ligand, that is, [Cu (μ-CH COO) (κO-DAPTA=O)] (1) and [Na(1κOO';2κO-DAPTA=O)(MeOH)] (BPh ) (2). The catalytic activity of 1 was tested in the Henry reaction and for the aerobic 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-mediated oxidation of benzyl alcohol. Compound 1 was also evaluated as a model system for the catechol oxidase enzyme by using 3,5-di-tert-butylcatechol as the substrate. The kinetic data fitted the Michaelis-Menten equation and enabled the obtainment of a rate constant for the catalytic reaction; this rate constant is among the highest obtained for this substrate with the use of dinuclear Cu complexes. DFT calculations discarded a bridging mode binding type of the substrate and suggested a mixed-valence Cu /Cu complex intermediate, in which the spin electron density is mostly concentrated at one of the Cu atoms and at the organic ligand.

Synthesis, Structural, and Cytotoxic Properties of New Water-Soluble Copper(II) Complexes Based on 2,9-Dimethyl-1,10-Phenanthroline and Their One Derivative Containing 1,3,5-Triaza-7-Phosphaadamantane-7-Oxide

“…In the last decades the coordination chemistry of PTA and PTA=O has seen a pronounced development justified by the search for water-soluble and stable transition metal complexes [21][22][23]. Currently, several examples of PTA=O coordination modes are known, where a tetrapodal ligand is connected to a metal center in the O- [24][25][26], N- [24,27,28], ON- [24,25], ONN- [10,29], NNN- [30], or ONNNmodes [29,31], achieving either discrete metallic units or polymeric compounds [32]. Among the biorelevant N-donor ligands suitable to afford new bioactive metal complexes, polypyridines represent a good choice due to a recognizable influence on a large variety of biological functions [33][34][35][36][37].…”

“…A series of Cu(I)-dmphen complexes stabilized by tertiary phosphines and other Cu(II)-dmphen coordination compounds have been also reported, but their poor solubility in polar solvents eventually prevented the application of these compounds as bioactive materials [38,39]. In particular, some of us have reported a number of water-soluble copper(I/II)-PTA-cage coordination networks [10,[40][41][42][43][44] as well as a discrete complexes [32,[40][41][42][43][45][46][47][48], which were evaluated successfully for their magnetic [10,43,45], catalytic [10,44], and luminescent properties [40,42,44,48].…”

Hydrosoluble Complexes Bearing Tris(pyrazolyl)methane Sulfonate Ligand: Synthesis, Characterization and Catalytic Activity for Henry Reaction

“…Activation of the carbonyl group using Lewis acidic metal compounds for catalytic Henry reaction is an approach that has been intensively studied and performed with (i) a well-defined complex [28,[43][44][45][46][47][48][49][50][51][52][53], (ii) an in situ generated complex by addition of a metal salt and a ligand [54][55][56][57][58][59], or (iii) a metal organic framework (MOF) [60][61][62]. In some instances a base is used to facilitate the deprotonation of the nitroalkane [56,63,64].…”

Recent Advances in Copper Catalyzed Alcohol Oxidation in Homogeneous Medium

“…Pombeiro and coworkers reported [27] the first example of a copper complex based on 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo [3. Figure 8).…”