DFT modeling of ligands in lanthanide chemistry: Is Ln[N(SiH3)2]3 a model for Ln[N(SiMe3)2]3?

DFT (B3PW91) calculations with large core ECPs for the whole series Ln[N(SiH3)2]3 have been carried out. The calculations find two types of geometries dependant on the silicon basis set. In the absence of d orbitals on Si, the calculations reproduce the helicoidal shape of the molecules and the absence of any agostic interaction. When d orbitals are added to the Si basis set, a corolla structure is obtained as a minimum, in addition to the less stable helicoidal structure. The greater stability of the corolla family is due to the presence of three Ln···Si–H agostic interactions, whose stabilising influence is overestimated by the modeling of SiMe3 by SiH3 in the vicinity of an electron-deficient lanthanide center. These results suggest that the coordination sphere of the lanthanide center could be highly sensitive to the level of calculation and that great caution should be taken in representing ligands in lanthanide chemistry.

[1]  O. Eisenstein,et al.  Do f Electrons Play a Role in the Lanthanide-Ligand Bonds? A DFT Study of Ln(NR2)3; R = H, SiH3 , 2000 .

[2]  B. Chaudret,et al.  A Unique Coordination of SiH4: Isolation, Characterization, and Theoretical Study of (PR3)2H2Ru(SiH4)RuH2(PR3)2 , 2000 .

[3]  B. Chaudret,et al.  Ruthenium Complexes Containing Two Ru−(η2-Si−H) Bonds: Synthesis, Spectroscopic Properties, Structural Data, Theoretical Calculations, and Reactivity Studies , 1999 .

[4]  B. Schimmelpfennig,et al.  Reduction of uranyl by hydrogen: an ab initio study , 1999 .

[5]  T. Saue,et al.  Theoretical studies of the actinides: method calibration for the UO22+ and PuO22+ ions , 1999 .

[6]  A. Cooper,et al.  Computational and Experimental Test of Steric Influence on Agostic Interactions: A Homologous Series for Ir(III) , 1999 .

[7]  Man-Fai Fan,et al.  Stability of the trans-Bis(H···Si) Structure in the Complex RuH2(PCy3)2(κ-η2-H···SiMe2-o-C6H4-SiMe2···H), Studied by Density Functional Theory , 1999 .

[8]  Carlo Adamo,et al.  A Theoretical Study of Bonding in Lanthanide Trihalides by Density Functional Methods , 1998 .

[9]  T. Ziegler,et al.  A UNIFIED VIEW OF ETHYLENE POLYMERIZATION BY D0 AND D0FN TRANSITION METALS. 1. PRECURSOR COMPOUNDS AND OLEFIN UPTAKE ENERGETICS , 1998 .

[10]  Adrian M. Simper,et al.  A two-centre implementation of the Douglas-Kroll transformation in relativistic calculations , 1998 .

[11]  Gregori Ujaque,et al.  Computational Evidence of the Importance of Substituent Bulk on Agostic Interactions in Ir(H)2(PtBu2Ph)2 , 1998 .

[12]  Carlo Adamo,et al.  Ionic versus covalent character in lanthanide complexes. A hybrid density functional study , 1997 .

[13]  J. Bertrán,et al.  Theoretical Study of the Hydrogen Exchange Coupling in the Metallocene Trihydride Complexes [(C5H5)2MH3]n+ (M = Mo, W, n = 1; M = Nb, Ta, n = 0) , 1996 .

[14]  D. Stalke,et al.  Lanthanide alkoxides. III: Four-coordinate anionic neodymium(III) alkoxides and amides , 1994 .

[15]  Thomas R. Cundari,et al.  Effective core potential methods for the lanthanides , 1993 .

[16]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[17]  M. Hursthouse,et al.  Benzophenone complexes of the lanthanides: Synthesis of [Ln{N(SiMe3)2}3(Ph2CO)] (L = La, Eu, Tb, Yb or Y) and X-ray crystal structure of the terbium complex , 1992 .

[18]  B. Chaudret,et al.  Theoretical calculations on niobium and tantalum trihydride complexes. Relations with the problem of quantum mechanical exchange coupling , 1991 .

[19]  P. Fulde,et al.  Ground state calculations of di‐π‐cyclooctatetraene cerium , 1991 .

[20]  R. Andersen,et al.  Divalent lanthanide chemistry. Preparation and crystal structures of sodium tris[bis(trimethylsilyl)amido]europate(II) and sodium tris[bis(trimethylsilyl)amido]ytterbate(II), NaM[N(SiMe3)2]3 , 1984 .