In Situ Generation of Carboxylate:  An Efficient Strategy for a One-Pot Synthesis of Homo- and Heterometallic Polynuclear Complexes

Abstract

An efficient strategy for synthesis of a wide range of homo- and heterometallic polynuclear complexes is proposed. The synthesis protocol consists of a two-step one-pot reaction. The first step is the in situ generation of carboxylate anions via oxidation of aromatic aldehydes by metal nitrates in air. The aldehydes act as solvents and are also involved in redox processes. Solutions containing solely transition metal cations and aromatic carboxylates are obtained following this procedure. The second step is a tunable "à la carte" formation of a series of various polynuclear carboxylato complexes from solutions obtained at the former stage upon addition of different solvents. The polarity and donor properties of the solvents play a key role in determination of the nuclearities of the complexes. Hydrolytic processes can induce the formation of oxo- or hydroxo-bridges inside the polynuclear core as well. Complexes of various nuclearities are obtained: from discrete tri-, hexa-, or octanuclear units to 1D polymers. This protocol can be adapted with disconcerting simplicity to the synthesis of heterometallic species with similar molecular structures to their homometallic analogues starting from stoichiometric mixture of metal nitrates under the same reaction conditions. Detailed description of synthesis and the molecular structure of one representative complex for each series are presented in this paper. The temperature dependence of magnetic susceptibility of the heterometallic 1-D MnCo chain reveals typical behavior of a ferrimagnetic chain. The low-temperature investigations on single crystals show significant Ising type magnetic anisotropy.

CuIIGdIII Cryogenic Magnetic Refrigerants and Cu8Dy9 Single‐Molecule Magnet Generated by In Situ Reactions of Picolinaldehyde and Acetylpyridine: Experimental and Theoretical Study

“…The resulting gem ‐diol anion transfers hydride ion to another carbonyl of picolinaldehyde, given 2‐picolinic acid ( L 2 ) and 2‐pyridinylmethanol ( L 1 ). By increase the ratio of alkaline triethylamine, both [Gd 4 Cu 8 ] (complex 2 ) and the reported mononuclear [Cu( L 2 ) 2 ]14b are simultaneously crystalized and grown as blue crystals in distinct shapes of cubic and needle‐like, respectively. The oxidation product ( L 2 ) may come from disproportionation (Cannizzaro) reaction as well as oxidation reaction by O 2 /NO 3 − , whereas the reduction product ( L 2 ) should originate from the former.…”

“…That is, [Gd III 2 Cu II 2 (OH) 2 (NO 3 ) 2.5 (OAc) 3.5 ( L 1 ) 2 ] n ( 1 ); [Gd III 4 Cu II 8 (OH) 8 (Me 3 CCOO) 8 ( L 1 ) 8 ](NO 3 ) 2 (OH) 2 ⋅15 H 2 O⋅3 MeCN ( 2 ); [Gd III 9 Cu II 8 (NO 3 ) 2 (OH) 10 ( L 3 ) 4 (OAc) 18 (H 2 O) 4 ](NO 3 ) 2 (OH) 3 ⋅22 H 2 O⋅4 MeOH ( 3⋅Gd ); [Dy III 9 Cu II 8 (NO 3 ) 2 (OH) 10 ( L 3 ) 4 (OAc) 18 (H 2 O) 4 ](NO 3 ) 2 (OH) 3 ⋅16 H 2 O⋅10 MeOH ( 3⋅Dy ). Here we report three types of [Ln x Cu y ] topologies accompanied by three kinds of reactions: Cannizzaro reaction, oxidation reaction and aldol reaction,14b, 18b, c and the latter two are the addition reactions between homomolecules. Magnetic measurements indicate that 3⋅Dy behaves as an SMM, and the other two Gd complexes exhibit significant magnetocaloric effect.…”

Tetrathiafulvalene-based group XV ligands: Synthesis, coordination chemistry and radical cation salts

“…The key step in the preparation of the complexes involves the in situ generation of the benzoate upon oxidation of benzaldehyde by nitrate salts of the transition metal, followed by the addition of the ligand and crystallization by slow diffusion [116]. The finetuning of the experimental conditions affords either bimetallic (Co5) or trimetallic (Co6-Co7) complexes.…”

Manganese and Cadmium Benzoate Complexes Having 8-Aminoquinoline Ancillary Ligand

“…These binding modes complicate selective synthesis of metal carboxylate complexes [1][2][3][4][5][6][7][8][9][10][11][12]. A general approach to rationalize selective synthetic procedures for polynuclear carboxylate complexes would require extensive structural study on carboxylate complexes prepared via different synthetic routes [13][14][15][16][17][18][19][20][21][22][23][24][25].…”