Computational density functional study of polypyrrolic macrocycles: analysis of actinyl-oxo to 3d transition metal bonding.
Density functional theoretical methods are used to study heterobimetallic compounds of a new form of binucleating Schiff-base polypyrrolic macrocycle, denoted [An(VI)O(2)(1)H(2)L], [An(V)O(2)(1)H(2)L](-), [An(VI)O(2)(TM)L] and [An(V)O(2)(TM)L](-), and containing actinyl ions AnO(2)(n+) (An = U, Np, Pu; n = 1, 2) and 3d transition metals (TM): no TM = 1, Mn = 2, Fe = 3, Co = 4, and Zn = 5. Calculated bond orders (TM-O2 = 0.36 to 0.81) provide evidence for partial bond formation between the transition metal (TM) and the actinyl-endo-oxygen for all 24 cases studied. Redox potentials for [An(VI)O(2)(1)H(2)L]/[An(V)O(2)(1)H(2)L](-) couples were found to have the same Np(VI/V) > Pu(VI/V) > U(VI/V) trend as previously studied for the [AnO(2)(H(2)O)(5)](2+/1+) couples, where Np(VI) is the most easily reduced to Np(V). Extrapolation from the earlier penta-aqua actinyl results is used to predict [An(VI)O(2)(1)H(2)L]/[An(V)O(2)(1)H(2)L](-) redox couples of U = -1.10 eV, Np = 0.25 eV, and Pu = 0.01 eV. The calculated redox potential for [U(VI)O(2)(1)H(2)L]/[U(V)O(2)(1)H(2)L](-) is within 0.08 eV of the value found by cyclic voltammetry (-1.18 eV, in THF/NBu(n)(4)BF(4) solvent).
Berard
Joel J
JJ
Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
Schreckenbach
Georg
G
Arnold
Polly L
PL
Patel
Dipti
D
Love
Jason B
JB