Crystal structure and catalytic activity of ruthenium (II)/dithiocarbamate complexes in the epoxidation of cyclooctene

• We synthesised and characterised ruthenium complexes containing dithiocarbamate ligands.
• The X-ray structure of the complexes was determined.
• The dithiocarbamate complexes were used as pre-catalysts on the epoxidation of cyclooctene.
• The complex Ru(dppb)(hexCS2)2 shows the best selectivity in terms of the epoxidation reaction of cis-cyclooctene.

Complexes with the general formula [Ru(dppb)(R)2] {where: dppb = 1,4-bis(diphenylphosphino)butane and R = piperidinedithiocarbamate (pipeCS2−) (1); morpholinedithiocarbamate (morphCS2−) (2); ethilenodiaminedithiocarbamate (ethCS2−) (3) and hexamethilenominedithiocarbamate (hexCS2−) (4)} were synthesised from [RuCl2(dppb)]2-μ-(dppb). The complexes were characterised by nuclear magnetic resonance of phosphorus (31P{1H} NMR), cyclic voltammetry (CV) as well as elemental analyses. The X-ray structures of (1), (2), and (3) were determined and are presented here. Additionally, the complexes (1–4) were used as pre-catalysts in the epoxidation of cyclooctene, and initial results show that complex (4) has a selectivity of 74% in the epoxide product, with 53% conversion. The epoxidation catalysed used iodosylbenzene (PhIO) as primary oxidant.

Syntheses, characterisations and catalytic epoxidation activities of dithiocarbamate complexes containing ruthenium were described. The epoxidation of cis-cyclooctene, using PhIO as primary oxidant, is shown to be dependent on the lability of biphosphine in the catalyst precursor, followed by its oxidation. The X-ray structures of [Ru(dppb)(pipeCS2)2] (1), [Ru(dppb)(morphCS2)2] (2) and [Ru(dppb)(ethCS2)2] (3) were determined.Figure optionsDownload as PowerPoint slide