Self‐Assembled [Cu 2 ] and [Cu 3 ] Complexes Supported by Pivalate and Propionate Functionalities: Synthesis, Crystal Structure, Thermal, and Magnetic Properties

In this research, two new Cu(II) complexes, namely a dinuclear complex, [Cu(H 2 O) 4 ] 2 [Cu 2 L(piv)] 2 Cl 4 ·H 2 O ( 1 ), and a trinuclear complex, [Cu 3 L(prop)(Cl) 2 ]·3H 2 O ( 2 ), were investigated. Their structural aspects, thermal behaviors and magnetic properties were explored, featuring a flexible multidentate organic ligand H 3 L (H 3 L = N , N′ ‐bis(2‐carboxybenzyl)‐ N , N′ ‐bis(2‐pyridylmethyl)‐1,3‐diaminopropan‐2‐ol), alongside the carboxylate coligands pivalate (piv = C(CH 3 ) 3 CO 2 − ) and propionate (prop = CH 3 CH 2 CO 2 − ). In the solid state structure of 1 , within the [Cu 2 ] complex, the Cu(II) ions are doubly‐bridged by one alkoxide group of L 3− ligand and one pivalate group, with nonbonded internuclear Cu···Cu separation of 3.467(2) Å. In contrast, the trinuclear [Cu 3 ] complex ( 2 ) exhibits three nonbonded internuclear Cu···Cu separations, with the values of 3.488(1), 3.362(1) and 3.349(1) Å. Thus, the structural design of 2 shows a triangular topology formed via the coordination arrangement of three Cu centers located at the corners of a nearly isosceles triangle. Thermogravimetric analysis showed that 1 and 2 are stable up to around 203 and 217 °C, respectively. Magnetic properties showed the presence of antiferromagnetic interactions with coupling constant ( J ) values of −310(1) cm −1 in 1 , and −47.1(1) and −55.3(1) cm −1 in 2 . The nature and mechanism of magnetic interactions have been delineated on account of magneto‐structural correlations.