Activation and functionalisation of carbon dioxide by bis-tris(pyrazolyl)borate-supported divalent samarium and trivalent lanthanide silylamide complexes.

Synthesis and reactivity with carbon dioxide (CO) of divalent samarium in the bis-tris(pyrazolyl)borate ligand environment has been reported. In addition, CO activation and functionalisation by lanthanide silylamides in the bis-tris(pyrazolyl)borate ligand environment was demonstrated. Reduction of the Sm(III) precursor [Sm(Tp)(OTf)] (Tp = hydrotris(1-pyrazolyl)borate; OTf = triflate) with KC yielded the insoluble Sm(II) multi-metallic coordination polymer [{Sm(Tp)}] 1-Sm.

Synthesis and Reactivity of Bis-tris(pyrazolyl)borate Lanthanide/Aluminum Heterobimetallic Trihydride Complexes.

Molecular heterobimetallic hydride complexes of lanthanide (Ln) and main-group (MG) metals exhibit chemical properties unique from their monometallic counterparts and are highly reactive species, making their synthesis and isolation challenging. Herein, molecular Ln/Al heterobimetallic trihydrides [Ln(Tp)(μ-H)Al(H)(N″)] [; Ln = Y, Sm, Dy, Yb; Tp = hydrotris(1-pyrazolyl)borate; N″ = N(SiMe)] have been synthesized by facile insertion of aminoalane [MeN·AlH] into the Ln-N amide bonds of [Ln(Tp)(N″)] (). Thus, this is a simple synthetic strategy to access a range of Ln/Al hydrides.

A Second Glass Transition Observed in Single-Component Homogeneous Liquids Due to Intramolecular Vitrification.

On supercooling a liquid, the viscosity rises rapidly until at the glass transition it vitrifies into an amorphous solid accompanied by a steep drop in the heat capacity. Therefore, a pure homogeneous liquid is not expected to display more than one glass transition. Here we show that a family of single-component homogeneous molecular liquids, titanium tetraalkoxides, exhibit two calorimetric glass transitions of comparable magnitude, one of which is the conventional glass transition associated with dynamic arrest of the bulk liquid properties, while the other is associated with the freezing out of intramolecular degrees of freedom.

Reduction chemistry yields stable and soluble divalent lanthanide tris(pyrazolyl)borate complexes.

Reduction of the heteroleptic Ln(III) precursors [Ln(Tp)(OTf)] (Tp = hydrotris(1-pyrazolyl)borate; OTf = triflate) with either an aluminyl(I) anion or KC yielded the adduct-free homoleptic Ln(II) complexes dimeric 1-Eu [{Eu(Tp)(:-Tp)}] and monomeric 1-Yb [Yb(Tp)]. Complexes 1-Ln have good solubility and stability in both non-coordinating and coordinating solvents. Reaction of 1-Ln with 2 PhPO yielded 1-Ln(OPPh3)2.