Binuclear nickel(II) complexes with 3,5-di-tert-butylbenzoate and 3,5-di-tert-butyl-4-hydroxybenzoate anions and 2,3-lutidine: the synthesis, structure, and magnetic properties

Two novel binuclear nickel(II) complexes [Ni2(O2CR)4(2,3-lut)2] (O2CR is anion of 3,5-di(tert-butyl)benzoic acid (bzo, 1) and 4-hydroxy-3,5-di(tert-butyl)benzoic acid (hbzo, 2); 2,3-lut is 2,3-lutidine) with four carboxylate bridges were synthesized. The structure of complex 1 was determined by X-ray diffraction. Both dimers 1 and 2 were characterized by elemental analysis, IR spectroscopy, and magnetic measurements. The presence of the α-substituent in the apical lutidine ligand leads to a distortion of the geometry of the metal carboxylate core in complex 1 as a result of short steric contacts Me(Lut)…O(OOCR) (3.134(7) Å). This is apparently responsible for a considerable decrease in the exchange parameters of complexes 1 and 2 (J =–30.0 and–23.6 cm–1, respectively) as compared to known analogues. Density functional calculations of the structure and magnetic properties of 1 and 2 were carried out by the UB3LYP/6-31G(d,p) method.