Nanocap‐Shaped Tin Phthalocyanines: Synthesis, Characterization, and Corrosion Inhibition Activity

Thermal and microwave reactions between [PcSn IV Cl 2 ] ( 1 ) and the potassium salts of eight fatty acids ( 2 a – h ) led to cis ‐[(RCO 2 ) 2 Sn IV Pc] compounds ( 3 a – h ) in yields ranging from 54 to 90 %. Compounds 3 a – h were fully characterized by elemental analysis, spectroscopy (IR, UV/Vis, multinuclear NMR), and seven X‐ray diffraction structures, whereby two different allotropes were observed in two cases. The two carboxylates in 3 have a cis anisobidentate binding mode, octacoordination of the tin atoms with square‐antiprismatic geometry, and π‐electron‐rich nanocap shapes. On account of the latter characteristics, 3 a – h compounds have anticorrosion properties. LPR and Tafel electrochemical methods were used to characterize the behavior of these derivatives in naturally aerated sour brine, which is a common environment in petroleum production and refinery operations. The measurement of the corrosion rate of carbon steel AISI 1018 in the presence of 3 a–h (500 ppm) gave efficiencies of 61–87 % for the inhibitor performance. Of the different derivatives examined, compounds 3 e and 3 h were the most effective corrosion inhibitor prototypes.