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The discovery of novel corrosion inhibitors for solution and coating applications is still an empirical process because of the large number of parameters that impact efficacy and the varied environmental conditions in which inhibitors are deployed. Moreover, conventional methods such as electrochemical and analytical techniques, and coating standard specifications can be extremely end-use focused, time and material intensive, and costly, making it prohibitive to screen new materials quickly at early stages of the discovery process. In an effort to address these challenges, we have continued to develop and deploy models and assays that can assist in accelerating the materials discovery process around novel corrosion inhibitors for different metals. In this paper we present how computational modelling, coupled with high-throughput optical and high-throughput electrochemical solution and coating assays, can be powerful tools that allow the rapid identification of prime candidates for further study. These experimental techniques are consistent with conventional % inhibition efficiency and neutral salt spray measurements, and provide additional and insightful information that cannot be easily or quickly obtained by traditional methods. Information extracted from the study of these chromium-based and small organic heterocyclic compounds reveals interesting structure–activity and structure–property relationships that will be applied in the design and discovery of new corrosion inhibitors.

Ab initio molecular orbital calculations using the 6-311G**, cc-pVDZ and aug-cc-pVDZ basis sets, with (MP2, QCISD, CCSD(T)) and without (HF) the inclusion of electron correlation indicate that decarboxylation reactions of alkoxyacyl (alkoxycarbonyl) radicals are significantly exothermic. Transition states (16) for these decarboxylation reactions are calculated to have CTS–OTS separations in the range: 1.813–1.892 A; these distances appear to be affected somewhat by steric compression. At the CCSD(T)/6-311G**//MP2/6-311G** level of theory, energy barriers of 75.9, 72.8, 67.0 and 60.3 kJ mol–1 are calculated for the decarboxylation reactions involving the methoxyacyl, ethoxyacyl, isopropoxyacyl and tert-butoxyacyl radicals (2) respectively, while the reverse reactions are calculated to require energies in excess of 130.9 kJ mol–1. By comparison, the decarbonylation reaction of the acetyl radical (8) is predicted to be significantly endothermic; methyl radicals are calculated to prefer to add to carbon monoxide with an energy barrier of only 24.0 kJ mol–1 at the CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level of theory, in good agreement with available experimental data.Similar calculations for reactions involving (methoxy)thioacyl, (methylthio)acyl and (methylthio)thioacyl radicals (12–14, R = Me) suggest that only (alkoxy)thioacyl radicals (12) provide synthetically useful β-fragmentation reactions, the remaining systems (13, 14) are unlikely to be useful as alkyl radical precursors in synthesis; the reverse reactions are calculated to be competitive with the β-fragmentation process in these cases.

Phenyltellurotris(trimethylsilyl)silane 4 and (4-fluorophenyltelluro)tris(trimethylsilyl)silane 5 react with methyl, 2-methylpropyl, cyclohexyl and phenyl substituted chloroformates (7, 11, 15, 19) in benzene and in the presence of tetrakis(triphenylphosphine)palladium(0) (4 mol%) to afford the corresponding aryltelluroformate (8, 9, 12, 13, 16, 17, 20, 21) in 50–79% yield; this procedure is also applicable to the preparation of (phenylseleno)formates and seleno- and telluro-esters.

119 Sn and 125Te NMR spectroscopies reveal that methyl, primary and secondary alkyl radicals, generated by reaction of phenyltelluroalkanes 4, 6, 7 with tributyltin hydride (benzene, AIBN initiator), are capable of displacing tributylstannyl radicals from (4-fluorophenyltelluro)tributylstannane to afford the 4-fluorophenyltelluroalkanes 3, 8, 9.