title: Experimental and theoretical comparison of actinide and lanthanide bonding in M[N(EPR(2))(2)](3) complexes (M = U, Pu, La, Ce; E = S, Se, Te; R = Ph, iPr, H).
abstract: Treatment of M[N(SiMe3)2]3 (M = U, Pu (An); La, Ce (Ln)) with NH(EPPh2)2 and NH(EPiPr2)2 (E = S, Se), afforded the neutral complexes M[N(EPR2)2]3 (R = Ph, iPr). Tellurium donor complexes were synthesized by treatment of MI3(sol)4 (M = U, Pu; sol = py and M = La, Ce; sol = thf) with Na(tmeda)[N(TePiPr2)2]. The complexes have been structurally and spectroscopically characterized with concomitant computational modeling through density functional theory (DFT) calculations. The An-E bond lengths are shorter than the Ln-E bond lengths for metal ions of similar ionic radii, consistent with an increase in covalent interactions in the actinide bonding relative to the lanthanide bonding. In addition, the magnitude of the differences in the bonding is slightly greater with increasing softness of the chalcogen donor atom. The DFT calculations for the model systems correlate well with experimentally determined metrical parameters. They indicate that the enhanced covalency in the M-E bond as group 16 is descended arises mostly from increased metal d-orbital participation. Conversely, an increase in f-orbital participation is responsible for the enhancement of covalency in An-E bonds compared to Ln-E bonds. The fundamental and practical importance of such studies of the role of the valence d and f orbitals in the bonding of the f elements is emphasized.
authors.affiliation: Chemistry Division and Associate Directorate for Chemistry, Life, and Earth Sciences, Los Alamos National Laboratory, Los Alamos, NM 87545, USA. gaunt@lanl.gov
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Gaunt
authors.forename: Sean D
authors.initials: SD
authors.lastname: Reilly
authors.forename: Alejandro E
authors.initials: AE
authors.lastname: Enriquez
authors.forename: Brian L
authors.initials: BL
authors.lastname: Scott
authors.forename: James A
authors.initials: JA
authors.lastname: Ibers
authors.forename: Perumal
authors.initials: P
authors.lastname: Sekar
authors.forename: Kieran I M
authors.initials: KI
authors.lastname: Ingram
authors.forename: Nikolas
authors.initials: N
authors.lastname: Kaltsoyannis
authors.forename: Mary P
authors.initials: MP
authors.lastname: Neu
mesh_terms: D008671:Actinoid Series Elements / Q000737:chemistry*; D001665:Binding Sites; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D008671:Actinoid Series Elements; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds