Comparisons of MN2S2vs. bipyridine as redox-active ligands to manganese and rhenium in (L-L)M'(CO)3Cl complexes.
The bipyridine ligand is renowned as a photo- and redox-active ligand in catalysis; the latter has been particularly explored in the complex Re(bipy)(CO)3Cl for CO2reduction. We ask whether a bidentate, redox-active MN2S2metallodithiolate ligand in heterobimetallic complexes of Mn and Re might similarly serve as a receptor and conduit of electrons. In order to assess the electrochemical features of such designed bimetallics, a series of complexes featuring redox active MN2S2metallodithiolates, with M = Ni2+, {Fe(NO)}2+, and {Co(NO)}2+, bound to M'(CO)3X, where M' = Mn and Re, were synthesized and characterized using IR and EPR spectroscopies, X-ray diffraction, cyclic voltammetry, and density functional theory (DFT) computations. Butterfly type structures resulted from binding of the convergent lone pairs of the cis-sulfur atoms to the M'(CO)3X unit. Bond distances and angles are similar across the M' metal series regardless of the ligand attached. Electrochemical characterizations of [MN2S2·Re(CO)3Cl] showed the redox potential of the Re is significantly altered by the identity of the metal in the N2S2pocket. DFT calculations proved useful to identify the roles played by the MN2S2ligands, upon reduction of the bimetallics, in altering the lability of the Re-Cl bond and the ensuing effect on the reduction of ReIto Re0.
Department of Chemistry, Texas A&M University, College Station, Texas, USA. marcetta@chem.tamu.edu.
Allen M
AM
Lunsford
Kristina F
KF
Goldstein
Matthew A
MA
Cohan
Jason A
JA
Denny
Nattamai
N
Bhuvanesh
Shengda
S
Ding
Michael B
MB
Hall
Marcetta Y
MY
Darensbourg