Electronic structures of trans-dioxometal complexes.
We have employed computational methods based on density functional theory to elucidate the effects of equatorial ligands on the electronic structures of trans-dioxometal complexes. In complexes with amine (sigma-only) equatorial donors, the (1)A(1 g)(b(2 g))(2)-->(1)E(g)(b(2 g))(1)(e(g))(1) excitation energy increases with metal oxidation state: Mo(IV) < Tc(V) < Ru(vi) and W(IV) < Re(V) < Os(VI). Increasing transition energies are attributed to enhanced oxometal pi-donor interactions in the higher valent central metals. But in complexes with cyanide equatorial donors, the (1)A(1 g)(b(2 g))(2)-->(1)E(g)(b(2 g))(1)(e(g))(1) energy remains roughly independent of metal oxidation state, likely owing to the compensating increased pi-donation from the pi(CN) orbitals to the metal d(xy) orbitals as the oxidation state of the metal increases.
Hummel
Patrick
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California Institute of Technology, 1200 E. California Blvd., Mail Code 139-74, Pasadena, CA 91125, USA.
Winkler
Jay R
JR
Gray
Harry B
HB