Rare Earth 2‐Methyl‐3‐furoate Complexes: Effect of Steric Hindrance on Corrosion Inhibitor Properties

Abstract

The preparation and characterization of six rare earth 2‐methyl‐3‐furoate (2m3fur) complexes are detailed in this study. Analysis through single‐crystal X‐ray diffraction, as well as powder XRD, reveals that all six compounds can be categorized into two structural groups: {[RE2(2m3fur)6(EtOH)]⋅H2O}n (RE = La, Ce, Pr) and [RE3(2m3fur)9]n (RE = Y, Er, Yb). These structural groups favour the formation of carboxylate coordinated linear polymers. The former complexes feature two distinct metal centers, with lattice water participating in a hydrogen bond with ethanol within the coordination sphere. The latter structures, involving erbium, ytterbium, and yttrium, consist of three unique metal centers: two eight coordinate, and one seven‐coordinated. In corrosion inhibition tests on mild steel in 0.01 M NaCl solution, the maximum efficiency was observed with [Y3(2m3fur)9]n at 59%, which is less effective compared to yttrium 3‐furoate complexes (90% efficiency). The results suggest that the steric effect of the methyl group adversely affects corrosion inhibition.