Journal article
Electronic Structure, Excited States, and Photoelectron Spectra of Uranium, Thorium, and Zirconium Bis(Ketimido) Complexes (C5R5)2M[−NCPh2]2 (M = Th, U, Zr; R = H, CH3)
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, Vol.109(24), pp.5481-5491
06/23/2005
Handle:
https://hdl.handle.net/2376/110396
PMID: 16839076
Abstract
Organometallic actinide bis(ketimide) complexes (C5Me5)2An[−NC(Ph)(R)]2 (where R = Ph, Me, and CH2Ph) of thorium(IV) and uranium(IV) have recently been synthesized that exhibit chemical, structural, and spectroscopic (UV−Visible, resonance-enhanced Raman) evidence for unusual actinide−ligand bonding. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682; Jantunen et al., Organometallics, 2004, 23, 4682; Morris et al., Organometallics, 2004, 23, 5142.] Similar evidence has been observed for the group 4 analogue (C5H5)2Zr[−NCPh2]2. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682.] These compounds have important implications for the development of new heavy-element systems that possess novel electronic and magnetic properties. Here, we have investigated M-ketimido bonding (M = Th, U, Zr), as well as the spectroscopic properties of the highly colored bis-ketimido complexes, using density functional theory (DFT). Photoelectron spectroscopy (PES) has been used to experimentally elucidate the ground-state electronic structure of the thorium and uranium systems. Careful examination of the ground-state electronic structure, as well as a detailed modeling of the photoelectron spectra, reveals similar bonding interactions between the thorium and uranium compounds. Using time-dependent DFT (TDDFT), we have assigned the bands in the previously reported UV−Visible spectra for (C5Me5)2Th[−NCPh2]2, (C5Me5)2U[−NCPh2]2, and (C5H5)2Zr[−NCPh2]2. The low-energy transitions are attributed to ligand-localized N p → CN π* excitations. These excited states may be either localized on a single ketimido unit or may be of the ligand−ligand charge-transfer type. Higher-energy transitions are cyclopentadienyl π → CN π* or cyclopentadienyl π → phenyl π* in character. The lowest-energy excitation in the (C5Me5)2U[−NPh2]2 compound is attributed to f−f and metal−ligand charge-transfer transitions that are not available in the thorium and zirconium analogues. Geometry optimization and vibrational analysis of the lowest-energy triplet state of the zirconium and thorium compounds also aids in the assignment and understanding of the resonance-enhanced Raman data that has recently been reported. [Da Re et al., J. Am. Chem. Soc., 2005, 127, 682.]
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- Title
- Electronic Structure, Excited States, and Photoelectron Spectra of Uranium, Thorium, and Zirconium Bis(Ketimido) Complexes (C5R5)2M[−NCPh2]2 (M = Th, U, Zr; R = H, CH3)
- Creators
- Aurora E ClarkRichard L MartinP. Jeffrey HayJennifer C GreenKimberly C JantunenJaqueline L Kiplinger
- Publication Details
- The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, Vol.109(24), pp.5481-5491
- Academic Unit
- Chemistry, Department of
- Publisher
- American Chemical Society
- Identifiers
- 99900547197901842
- Language
- English
- Resource Type
- Journal article