α,ω-Diferrocenyl Cumulene Molecular Wires Studied by Density Functional Theory

Abstract

Density functional theory calculations for neutral and oxidized diferrocenyldiphenylcumulenes, [Fc(Ph)C n (Ph)Fc] with n ) 2, 4, 6, 8, were performed at the B3LYP/6-31G level without any restrictions in symmetry. Geometrically, of the four possible diasteromeric structures of the neutral cumulenes, no preferential conformation was revealed, and the calculated structures reproduce the experimental X-ray structural data quite well. The spin density of all mono-and dications is located on the iron atoms, but not on the cumulene chain. Calculations of the ionization potentials for monocations show a breakdown of Koopmans' theorem. A calibration procedure was proposed for evaluation of vertical ionization potentials, resulting in values with experimental accuracy. UV-visible absorptions are assigned in terms of their band maximums, transition energies, and bandwidths on the basis of deconvoluted experimental spectra and on the basis of comparison with structurally related compounds. Calculations of the characteristic high-frequency symmetric vibrations of the cumulene chain show a very good match with experimental Raman bands. Redox potentials in solution are calculated by a simplified model on the basis of empirical findings; the results reproduce the experimental half-wave potentials quite satisfactorily and allow an estimate of an electrochemical decay slope and an effective conjugation limit in these cumulene molecular wires. The structural, chemical, optical, electrochemical, and molecular orbital properties of 2-31 make ferrocenyl cumulenes very promising molecular objects with great potential in molecular-scale electronics in comparison with pure organic molecular wires.

Application of DFT for the modeling of the valence region photoelectron spectra of boron and d‐element complexes and macromolecules

“…In addition to ferrocene, results for the derivatives of other iron and chromium π ‐complexes (bis(benzene)chromium (η 6 ‐C 6 H 6 )Cr(η 6 ‐C 6 H 6 ), benzene chromium tricarbonyl (η 6 ‐C 6 H 6 )Cr(CO) 3 , and cyclobutadiene‐iron tricarbonyl (η 4 ‐C 4 H 4 )Fe(CO) 3 ) have been reported . It has been shown that the δ values and localization degree of 3 d AOs are stable and universal.…”

Electronic Structure and Chain‐Length Effects in Diplatinum Polyynediyl Complexes trans,trans‐[(X)(R3P)2Pt(CC)nPt(PR3)2(X)]: A Computational Investigation

“…As the chain lengthens, some negative charge flows towards the midpoint. Thus, 77 % of the total charge on the chain in PtC 26 Pt is found at C1/C2. Charge alternation patterns also develop.…”

“…Now the cumulative bond orders decrease from 2.664 to 2.600 (2.4 %), again with no change in the s population. Indeed, all CC bonds undergo bond-order reduction through the p manifold, although comparisons must be made over narrower ranges (e.g., from PtC 10 Pt to PtC 26 Pt for C5/C6 CC). In contrast, the C2/C3 CÀC single bond order shows a gradual increase from 0.967 to 0.973 (0.62 %).…”

“…[3b, [23][24][25][26][27][28] However, only one has involved species with comparable carbon-chain lengths, [28] and none have examined conformational distortions. While our data were being readied for publication, an important complementary treatment of electronic transitions in the digold complexes [(R 3 P)Au(C C) n Au(PR 3 )] (n = 1-6) appeared.…”

Ferrocene‐Containing Optically Active Liquid‐Crystalline Side‐Chain Polysiloxanes with Planar Chirality

“…A similar strategy was recently reported to yield good predictions of the properties of ferrocene-containing molecules. [38] Compound 3 can adopt several conformations. In particular, we considered the conformation at the carboxylic acid group, the conformation at the two ester groups, and the conformation at the ether group.…”