Electrocatalytic reduction of carbon dioxide based on 2,2'-bipyridyl complexes of osmium

Abstract

The complex cis-[Os(bpy)2(CO)H]+ (bpy is 2,2'-bipyridine) has been found to be an electrocatalyst for the reduction of C02 in CH$N containing 0.1 M tetra-n-butylammonium hexafluorophosphate at glassy carbon or Pt electrodes. Under anhydrous conditions CO is the dominant product, but addition of water results in up to 22% formate anion. Kinetic parameters derived by digital simulation of cyclic voltammograms under electrocatalytic conditions are consistent with a rate-determining associative step (kl) in which C02 undergoes a reaction with the direduced complex, [Os(bpy)z(CO)H]-, to form an intermediate. This intermediate either gives CO or a second intermediate which is a source of CO or formate by competitive pathways that follow the rate-determining step(s). On the basis of the results of isotopic labeling studies, neither the bound CO nor H-groups are involved in the reduction of CO1. The kinetics of reduction of C02 by the twice-reduced complexes ~is-[M(bpy)~(CO)R]-(M = Os, R = H, Me, Ph; M = Ru, R =

Reflectance infrared and UV–visible spectroelectrochemical studies on a series of [Ni3(µ3-L)(µ3-I)(µ2-dppm)3][PF6] (L = CO; CNR, R = alkyl, aryl; dppm = Ph2PCH2PPh2) clusters

“…Although the spectrometer can be configured to scan to 27 000 cm-', the region past 22 000 cm-' is unreliable due to the low power of our visible source. Similar results were obtained for other selected nickel clusters (3)(4)(5)(6). Methods for increasing the sensitivity of the SEC response past 22 000 cm-' are being pursued.…”

“…Infrared SEC studies on [Ni3(p3-CNR)(p3-I)(p2-dppm)3]+ (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) A distinguishing feature of the IR spectra for many of the isocyanide capped clusters 2-14 is the appearance of ttvo v(C=N) absorption bands, both in the solid state and in solution. Isotope labeling experiments confirmed that the appearance of two v(C=N) bands was a result of a Fermi resonance between the v(C=N) fundamental and the first overtone of the v(N-C(alky1)) fundamental (1).…”

“…The synthesis and physical properties of a class of T-acceptor capped trinuclear nickel clusters [Ni3(k3-L)(k3-I)(k2-dppm),]' (L = CO (1); CNR, R = CH, (2), i-C,H, (3), CGHll (41, t-C4H9 (51, CH2C6H5 (6), C6H5 (7), p-CGH41 (8), p-C6H4F (91, p-C6H,CH3 (lo), p-C6H4CF3 ( l l ) , p-C6H40CH3 (12), and P -C~H~C N ( 1 3 , 2,6-(CH3)2C6H3 (14); dppm = Ph,PCH,PPh,) has been recently reported ( 1 4 (2)(3)(4)(5)(6) ~k N i @ = CNR, R = ary1 (7)(8)(9)(10)(11)(12)(13)(14) \I/ For personal use only.…”

“…However, due to the importance of C 0 2 activation, a variety of transition metal catalysts able to effectively catalyze the reduction of C 0 2 have been reported (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). The methyl isocyanide capped cluster (2) is a known electrocatalyst for the reduction and subsequent activation of carbon dioxide in acetonitrile (2).…”

Splitting CO 2 into CO and O 2 by a single catalyst

“…Progress has also been made on catalytic reduction of CO 2 to CO (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). Both present a formidable challenge in chemical reactivity.…”