TY - JOUR
T1 - Comparative absorption, electroabsorption and electrochemical studies of intervalence electron transfer and electronic coupling in cyanide-bridged bimetallic systems
T2 - Ancillary ligand effects
AU - Vance, Fredrick W.
AU - Slone, Robert V.
AU - Stern, Charlotte L.
AU - Hupp, Joseph T.
N1 - Funding Information:
We acknowledge helpful discussions with Dr. Marshall Newton and Prof. Jeff Curtis. We thank the US Department of Energy, Office of Research, Division of Chemical Sciences (Grant No. DE-FG02-87ER13808). FWV thanks the Materials Research Center at Northwestern University (Grant No. NSF-DMR-9632472) for a graduate assistantship. Supporting Information Available: A description of X-ray crystallographic information, including a CIF format file, is available.
PY - 2000/3/1
Y1 - 2000/3/1
N2 - Electroabsorption or Stark spectroscopy has been used to evaluate the systems (NC)5M(II)-CN-Ru(III)(NH3)5/1- and (NC)5M(II)-CN-Ru(III)(NH3)4py1-, where M(II)=Fe(II) or Ru(II). When a pyridine ligand is present in the axial position on the Ru(III) acceptor, the effective optical electron transfer distance - as measured by the change in dipole moment, |Δμ| - is increased by more than 35% relative to the ammine substituted counterpart. Comparison of the charge transfer distances to the crystal structure of Na[(CN)5Fe-CN-Ru(NH3)4py] · 6H2O reveals that the Stark derived distances are ~50% to ~90% of the geometric separation of the metal centers. The differences result in an upward revision in the Hush delocalization parameter, c(b)/2, and of the electronic coupling matrix element, H(ab), relative to those parameters obtained exclusively from electronic absorption measurements. The revised parameters are compared to those, which are obtained via electrochemical techniques and found to be in only fair agreement. We conclude that the absorption/electroabsorption analysis likely yields a more reliable set of mixing and coupling parameters. (C) 2000 Elsevier Science B.V.
AB - Electroabsorption or Stark spectroscopy has been used to evaluate the systems (NC)5M(II)-CN-Ru(III)(NH3)5/1- and (NC)5M(II)-CN-Ru(III)(NH3)4py1-, where M(II)=Fe(II) or Ru(II). When a pyridine ligand is present in the axial position on the Ru(III) acceptor, the effective optical electron transfer distance - as measured by the change in dipole moment, |Δμ| - is increased by more than 35% relative to the ammine substituted counterpart. Comparison of the charge transfer distances to the crystal structure of Na[(CN)5Fe-CN-Ru(NH3)4py] · 6H2O reveals that the Stark derived distances are ~50% to ~90% of the geometric separation of the metal centers. The differences result in an upward revision in the Hush delocalization parameter, c(b)/2, and of the electronic coupling matrix element, H(ab), relative to those parameters obtained exclusively from electronic absorption measurements. The revised parameters are compared to those, which are obtained via electrochemical techniques and found to be in only fair agreement. We conclude that the absorption/electroabsorption analysis likely yields a more reliable set of mixing and coupling parameters. (C) 2000 Elsevier Science B.V.
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U2 - 10.1016/S0301-0104(99)00400-0
DO - 10.1016/S0301-0104(99)00400-0
M3 - Article
AN - SCOPUS:0034158636
SN - 0301-0104
VL - 253
SP - 313
EP - 322
JO - Chemical Physics
JF - Chemical Physics
IS - 2-3
ER -