N-Benzyloxycarboxamides and Their Zirconium Complexes: Synthesis, Structures, and Thermal Properties

N-Benzyloxycarboxamides (HL) and corresponding zirconium(IV) complexes [Zr(L)4] (L = R'C(O)NOR, R = CH2–C6H5; R' = CH3 for L = baa or R' = C6H5 for L = bba) are synthesized and characterized to reveal the influence of the aromatic substituent on the structures and thermal properties. The structures of Hbba, [Zr(baa)4], and [Zr(bba)4] (CIF files CCDC nos. 2 474 365, 2 474 366, and 2 474 367, respectively) are determined by single-crystal X-ray diffraction (SC-XRD) and compared with those of N‑methoxybenzamide analogues Hmba and [Zr(mba)4] (R = CH3, R' = C6H5). The compounds are also studied by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The thermodynamic parameters for melting of Hbba and [Zr(baa)4] have been determined for the first time. In the [Zr(L)4] complexes, the introduction of the benzyl group into L results in the disappearance of the low-temperature structural transitions (L = mba) and a decrease in the melting points (L = baa, bba). The melting points of N‑alkoxybenzamides increase in the order L = mba < bba. Under the TGA conditions at comparable molecular weights, the [Zr(mba)4] complex partially evaporates, whereas [Zr(baa)4] decomposes.