Molybdenum doubly bridged and chelate nitrosyl complexes incorporating saturated n-alkanediolate ligands

The redox-active doubly bridged species [{Mo(NO)(TpMe2)Q}2] [TpMe2 = tris(3,5-dimethylpyrazol-1-yl)hydroborate, Q = O(CH2)nO, n = 3, 5, or OCH2(CF2)n−2CH2O, n = 5, 6], and a chelate complex [Mo(NO)-(TpMe2)O(CH2)5O] were prepared and characterised by elemental and mass analyses, 1H NMR and IR spectroscopy. The bimetallic species with C3, C5, and C5(F) bridges exhibit two well-resolved reduction processes in their cyclic voltammograms (ΔE1/2 values of 290, 170, and 170 mV, respectively). These results indicate that the presence of the second bridge increases the extent of electrochemical interactions (by ca. 90–130 mV) in comparison with their singly bridged analogues. All non-fluorinated and the chelate species were catalytically active in cathodic reduction of chloroform.

Graphical abstractNovel molybdenum nitrosyls have been prepared with the purpose of investigating the electronic interactions between the metal centres linked by two [O(CH2)nO]2− or [OCH2(CF2)n−2CH2O]2− bridges. The chelate complex [Mo(NO)(TpMe2)O(CH2)5O] was also obtained. A subsequent and important part of our research was an investigation of the catalytic activity of the new species in the electroreduction of chloroform.Figure optionsDownload full-size imageDownload as PowerPoint slide