Separation of Metal Binding and Electron Transfer Sites as a Strategy To Stabilize the Ligand-Reduced and Metal-Oxidized Form of [Mo(CO)4L]

0369241 - ÚFCH JH 2012 RIV US eng J - Journal Article
Bulak, E. - Varnali, T. - Schwederski, B. - Bubrin, D. - Fiedler, Jan - Kaim, W.
Separation of Metal Binding and Electron Transfer Sites as a Strategy To Stabilize the Ligand-Reduced and Metal-Oxidized Form of [Mo(CO)4L].
Organometallics. Roč. 30, č. 23 (2011), s. 6441-6445. ISSN 0276-7333. E-ISSN 1520-6041
R&D Projects: GA ČR GA203/09/0705
Institutional research plan: CEZ:AV0Z40400503
Keywords : Electron Transfer Sites * [Mo(CO)4L] * metal carbonyl complexes
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.963, year: 2011

The zerovalent metal in [Mo(CO)4(bmiq)] binds the two imidazole-N-imine donors of 2,3-bis(1-methylimidazol-2-yl)quinoxaline (bmiq), resulting in a seven-membered chelate ring coordinated in cis configuration. DFT calculations confirm the preference for a seven-membered vs five-membered ring chelation alternative as well as the experimental structural parameters. The complex is reversibly reduced in CH2Cl2 at −2.08 V and reversibly oxidized at −0.14 V vs ferrocenium/ferrrocene. The facilitated oxidation to a stable cation is attributed to the donor effect from the imidazole rings. In agreement with the DFT-calculated characteristics of the HOMO and LUMO, the in situ EPR studies at a Pt electrode reveal a MoI signature for the cation (g1 = 1.967, g2 = 1.944, g3 = 1.906; Aiso(95,97 Mo) = 50 G) and a quinoxaline radical-type EPR spectrum with dominant 14N coupling (2 N) of 6.0 G for the anion.
Permanent Link: http://hdl.handle.net/11104/0203358