Rare Earth 4‐Hydroxyphenylacetate Complexes: Synthesis, Structural Characterization, and Corrosion Inhibition Properties

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) 2024-11
• Main Authors: Salpadoru Thuppahige, Naveena Yasaswin, Guo, Zhifang, Deacon, Glen B., Somers, Anthony E., Junk, Peter Courtney
• Format: Article
• Language: English
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.202400180

Four different structural types of rare earth aqua 4‐hydroxyphenylacetate complexes {[Ce(L)3(H2O)2]⋅H2O}n (a), {[RE2(L)6(H2O)]⋅4H2O]}n (RE = Nd (b), Gd (c)), {[RE2(L)6(H2O)]⋅3H2O]}n (RE = Dy (d), Y (e)), {[RE2(L)6(H2O)]⋅5H2O]}n (RE = Er (f), Yb (g)), (L = 4‐hydroxyphenylacetate) have been synthesized by the metathesis reactions of corresponding rare earth metals chlorides or nitrates and sodium 4‐hydroxyphenylacetate (NaL). All compounds were obtained as 1‐D polymeric structures, with a common carboxylate coordination mode of chelating bridging. The structure of a differs in being a monometallic repeating unit and having two coordinated waters whilst the others have binuclear repeating units that resulted from the alternating coordination of one water molecule along the chain. Corrosion tests by the weight loss method and potentiodynamic polarisation tests revealed that {[Gd2(L)6(H2O)]⋅4H2O}n has the best corrosion inhibition properties for mild steel in 0.01 M NaCl. Furthermore, all a‐g complexes are more effective corrosion inhibitors than both the aqua and 2,2’‐bipyridine (bpy) complexes of unsubstituted phenylacetate indicating that 4‐OH substitution of phenylacetate enhances anti‐corrosion properties.