The Front Cover shows our rare earth corrosion inhibitor work. Corrosion is a significant burden to infrastructure, including bridges, and we have shown that incorporation of steric bulk about heteroatoms on the ligands bound to rare earth atoms (right figure) affects the ability to inhibit corrosion, compared to when we have open access to these heteroatoms (left figure). The artwork for the cover was done by Vidushi Vithana. More information can be found in the Research Article by P. C. Junk and co-workers.

The preparation and characterization of six rare earth 2-methyl-3-furoate (2m3fur) complexes are reported. All compounds belong to two structural groups: {[RE₂(2m3fur)₆(EtOH)] ⋅ H₂O}_n (RE=La, Ce, Pr) and [RE₃(2m3fur)₉]_n (RE=Y, Er, Yb). In corrosion inhibition tests on mild steel in 0.01 M NaCl solution, the maximum efficiency was observed with [Y₃(2m3fur)₉]_n. The results suggest that the steric effect of the methyl group adversely affects corrosion inhibition.

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 belong to one of 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 feature carboxylate coordinated linear polymers. The former complexes have two distinct metal centers, one ten coordinate and one nine, with lattice water participating in a hydrogen bond with coordinated ethanol. The latter structures, involving erbium, ytterbium, and yttrium, have 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 than yttrium 3-furoate (90 % efficiency). The results suggest that the steric effect of the methyl group adversely affects corrosion inhibition.