Binuclear copper(ii) and nickel(ii) complexes based on N,N′-bis(3-formyl-5-tert-butylsalicylidene)-1,3-diaminopropan-2-ol: physicochemical and theoretical study

Abstract

Binuclear Cu II and Ni II complexes with exogenous acetate and pyrazolate bridges were synthesized and studied. It was shown that the  2 coordination of the DMSO molecule in an acetate bridged Cu II complex leads to the inversion of the sign of the exchange interaction parameter. Quantum chemical calculations of the geometry of the complexes and the magnetic exchange parameters showed that the role of the DMSO molecule is to stabilize the "distorted" conformation of metallocycles.Hydrazones and azomethines of multifunctional carbo nyl compounds are among the most extensively studied ligands in modern coordination and supramolecular chem istry. 1-4 These ligand systems are characterized by the formation of binuclear complexes exhibiting ex change interactions between metal ions, which can be both antiferro and ferromagnetic. 5-10 The magnetochemi cal analysis of such exchange coupled systems is an important area of coordination chemistry. The chal lenge of this area is to prepare polynuclear complexes hav ing a high magnetic moment and capable of sustain ing magnetization, which are known as single molecule magnets. 11-15There are a lot of literature data on the structures and magnetic properties of binuclear complexes with bis azomethines of 1,3 diaminopropan 2 ol based on salicyl aldehyde or  diketones. 10 However, only complexes based on symmetrical macrocyclic bis azomethines of 1,3 diaminopropan 2 ol and 2,6 diformyl 4 R phenols were described. 1, [16][17][18] In the present work, we report on the results of the study of binuclear copper(II) and nickel(II) complexes based on N,N´ bis(3 formyl 5 tert butylsalicylidene) 1,3 diaminopropan 2 ol (H 3 L).Due to the presence of two free formyl groups in the azomethine molecule H 3 L, it is possible not only to pre pare binuclear complexes with an asymmetrical exchange fragment but also to form ligand systems with different amines and hydrazines capable of chelating two more metal ions. This opens a route to the synthesis of both homo and heteronuclear complexes containing four paramag netic exchange coupled centers. ExperimentalThe compounds H 3 L and [Cu 2 L(OAc)] (1) were synthesized according to a procedure described earlier. 19 The DMSO solvate of (     2 acetato O,O´) [     2 1,3 bis(3 formyl 5 tert butylsalicylidenealdiminato)propan 2 olate O,N,N´]

Physico-chemical study of the complex formation between 2-(tosylamino)benzaldehyde bishydrazones and transition metal ions

“…Addition of D 2 O led to the complete suppression of the signals of protons of NH groups. Owing to the presence of additional donating nitrogen atoms in the structure, bishydrazones of salicylic aldehyde derivatives can form both binuclear coordination compounds IVa (structurally similar to the complexes with the ligands based on 1,3diaminopropan-2-ol [9,23,[30][31][32][33][34][35][36][37][38][39][40][41][42]), and metal chelates IVb with two metal ions having nonequivalent coordination surroundings [4,9,[43][44][45].…”

“…Analysis of the data available on magnetic properties of the complexes IVa [9,23,[30][31][32][33][34][35][36][37][38][39][40][41][42] and quantum-chemical simulation of the exchange parameters [38][39][40][41][42] demonstrated that realization of the symmetric structure assumed strong antiferromagnetic exchange interaction between ions of the metal, significantly affected by the electronic properties of the substituents both in the chelate fragment and in the salicylic aldehyde part of the molecule. In the case of complexes IVb, antiferromagnetic exchange of intermediate strength (2J = -160 to -290 cm -1 ) was observed; the value was not much affected by the substituents nature [43][44][45].…”