Molybdenum(VI) complexes of Schiff bases derived from salicylaldehyde and 2-aminoethanethiol (cysteamine)

Abstract

The reaction of salicylaldehyde and 2-aminoethanethiol (cysteamine) in methanol results in two distinct products: a yellow oil, 2-(2-mercaptoethyliminomethyl)phenol, and a yellow crystalline solid, 2,2'-[dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenol, which is an oxidation product of the former. The latter compound may also be prepared from salicylaldehyde and 2,2'-dithio-bis(ethylamine) (cystamine) in methanol.

2-(2''-Mercaptoethyliminomethyl)phenol reacts with MoO₂(acac)₂ (acac = pentane-2,4-dionate) in methanol to yield a red crystalline solid with empirical formula MoO₂(mep) [mep = 2-(2"- mercaptoethyliminomethyl)phenolate]. This red solid exists as a dimer in the solid state. It forms adducts with dimethyl sulfoxide, hexamethylphosphoric acid triamide and pyridine.

2,2'-[Dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenol reacts with MoO₂(acac)₂ to yield a pale yellow solid. It is a monomeric compound whose formula is MoO₂(dbp) {dbp = 2,2'- [dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenolate}. It does not form an adduct and is decomposed by an excess of tetramethylammonium hydroxide in methanol.