Group 2 metal (Mg, Ca, Sr) silylamides supported by a cyclen-derived macrocyclic polyamine

Amidomagnesium cations

We report the synthesis, structure and reactivity of molecular amidomagnesium cations bearing tris{2-(dimethylamino)-ethyl}amine (Me₆TREN). Me₆TREN binds to the cationic magnesium centre exhibiting κ⁴ and κ³ coordination modes in [Me₆TREN-Mg-N(SiHMe₂)₂]⁺ and [Me₆TREN-Mg-N(SiMe₃)₂]⁺ respectively. [Me₆TREN-Mg-N(SiHMe₂)₂]⁺ reacts with benzophenone resulting in the insertion of the carbonyl group across β-SiH bond. The reaction between [Me₆TREN-Mg-N(SiMe₃)₂]⁺ and CO₂ leads to [Me₆TREN-Mg-OSiMe₃]⁺, while the reaction with H₂O results in [Me₆TREN-Mg-OH]₂²⁺. Attempts to prepare hydridomagnesium cations from [Me₆TREN-Mg-N(SiMe₃)₂]⁺ using KH resulted in the precipitation of MgH₂ and the isolation of [(Me₆TREN)K(THF)₃]⁺.

Barium complexes with crown-ether-functionalised amidinate and iminoanilide ligands for the hydrophosphination of vinylarenes

Two barium-amide complexes bearing crown-ether-functionalised amidinate and iminoanilide ligands that act as competent precatalysts for the intermolecular hydrophosphination of vinylarenes are presented.

Heterobimetallic Ba/Li and Ca/Li amides and diphenylmethanide

Rare examples of stable heterobimetallic Ca/Li and Ba/Li amido polymeric species, as well as an ate Ca/Li diphenylmethanide compound stable in ethers, have been structurally characterised. Intra- and intermolecular metal⋯H–Si interactions are shown to play a key role.

A monoanionic NNNN-type macrocyclic ligand for electropositive metal centers

The coordination of a mono(amido) triamine macrocyclic ligand Me₃TACD derived from cyclen (1,4,7,10-tetraazacyclododecane or [12]aneN₄) toward electropositive metal centers is surveyed. This NNNN-type monoanionic macrocyclic ligand is capable of stabilizing a variety of metal coordination environments that are commonly not amenable to stable coordination spheres. Metal complexes supported by Me₃TACD include hydrides, hydrocarbyls, silyls, and amides. Protection of one hemisphere of a large metal center allows, as in the case of metallocene scaffolds for early transition metals, deaggregation and control of reactivity.