title: Synthesis and solid-state structures of pyrazolylmethane complexes of the rare earths.
abstract: In this paper, we report the first examples of trispyrazolylmethane complexes of rare earths. Reaction of LnCl3 with Tpm* (tris(3,5-dimethylpyrazolyl)methane) in THF or acetonitrile gives good yields of the [Ln(Tpm*)Cl3] (Ln = Y, Ce, Nd, Sm, Gd, Yb). Tpm* adducts of the lanthanide triflates [Ln(Tpm*)(OTf)3(THF)] (Ln = Y, Ho, Dy) may also be prepared. The X-ray crystal structures of [Y(Tpm*)Cl3], [Sm(Tpm*)Cl3(THF)], and [Ln(Tpm*)(OTf)3(THF)] (Ln = Y, Ho) are reported. The halide/triflate complexes may be used to prepare the aryloxide complexes [Ln(Tpm*)(OArMe2)3] (Ln = Y, Nd, Sm, Yb; ArMe2 = C6H3-2,6-(CH3)2), which are fluxional in solution as a result of interactions between the Tpm* and the aryloxide groups. The structures of the Nd and Sm complexes have been determined. Finally, the reaction of [Nd(BH4)3(THF)3] with Tpm* in THF results in the displacement of two THF molecules to give [Nd(Tpm*)(BH4)3(THF)]. Infrared spectra are consistent with tridentate borohydride coordination. The X-ray structures of these compounds indicate that the Tpm* ligand is less strongly bound than its anionic trispyrazolylborate analogues.
authors.affiliation: Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London, WC1H 0AJ United Kingdom. a.sella@ucl.ac.uk
authors.forename: Andrea
authors.initials: A
authors.lastname: Sella
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Brown
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Steed
authors.forename: Derek A
authors.initials: DA
authors.lastname: Tocher
mesh_terms: D018360:Crystallography, X-Ray; D008674:Metals, Rare Earth / Q000737:chemistry*; D008697:Methane / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*
chemical_list: D008674:Metals, Rare Earth; D009942:Organometallic Compounds; D011720:Pyrazoles; D008697:Methane