title: Highly fluorinated tris(indazolyl)borate silylamido complexes of the heavier alkaline earth metals: synthesis, characterization, and efficient catalytic intramolecular hydroamination.
abstract: Heteroleptic silylamido complexes of the heavier alkaline earth elements calcium and strontium containing the highly fluorinated 3-phenyl hydrotris(indazolyl)borate {F12-Tp(4Bo, 3Ph)}(-) ligand have been synthesized by using salt metathesis reactions. The homoleptic precursors [Ae{N(SiMe3)2}2] (Ae = Ca, Sr) were treated with [Tl(F12-Tp(4Bo, 3Ph))] in pentane to form the corresponding heteroleptic complexes [(F12-Tp(4Bo, 3Ph))Ae{N(SiMe3)2}] (Ae = Ca (1); Sr (3)). Compounds 1 and 3 are inert towards intermolecular redistribution. The molecular structures of 1 and 3 have been determined by using X-ray diffraction. Compound 3 exhibits a Sr⋅⋅⋅MeSi agostic distortion. The synthesis of the homoleptic THF-free compound [Ca{N(SiMe2H)2}2] (4) by transamination reaction between [Ca{N(SiMe3)2}2] and HN(SiMe2H)2 is also reported. This precursor constitutes a convenient starting material for the subsequent preparation of the THF-free complex [(F12-Tp(4Bo, 3Ph))Ca{N(SiMe2H)2}] (5). Compound 5 is stabilized in the solid state by a Ca⋅⋅⋅β-Si-H agostic interaction. Complexes 1 and 3 have been used as precatalysts for the intramolecular hydroamination of 2,2-dimethylpent-4-en-1-amine. Compound 1 is highly active, converting completely 200 equivalents of aminoalkene in 16 min with 0.50 mol % catalyst loading at 25 °C.
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination), BP 44099, 205 route de Narbonne, 31077 Toulouse Cedex 4 (France); Université de Toulouse, UPS, INPT, LCC, 31077 Toulouse Cedex 4 (France).
authors.forename: Nuria
authors.initials: N
authors.lastname: Romero
authors.forename: Sorin-Claudiu
authors.initials: SC
authors.lastname: Roşca
authors.forename: Yann
authors.initials: Y
authors.lastname: Sarazin
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Carpentier
authors.forename: Laure
authors.initials: L
authors.lastname: Vendier
authors.forename: Sonia
authors.initials: S
authors.lastname: Mallet-Ladeira
authors.forename: Chiara
authors.initials: C
authors.lastname: Dinoi
authors.forename: Michel
authors.initials: M
authors.lastname: Etienne
keywords: agostic interactions; alkaline earth metals; hydroamination; ligands; metathesis