Synthesis of α-methylene-δ-valerolactone and its selective polymerization from a product mixture for concurrent separation and polymer production.

We report the continuous, gas-phase synthesis of α-methylene-δ-valerolactone (MVL) from δ-valerolactone (DVL) and formaldehyde (FA) over alkaline earth oxide catalysts. MgO, CaO, and BaO supported on silica (∼5 wt%) were active for MVL production (613 K, 0.4 kPa DVL, 1.

The Influence of Phosphorus Substituents on the Structures and Solution Speciation of Trivalent Uranium and Lanthanide Phosphinodiboranates.

Here, we report the mechanochemical synthesis and characterization of homoleptic uranium and lanthanide phosphinodiboranates with isopropyl and ethyl substituents attached to phosphorus. M(HBPPrBH) complexes with M = U, Nd, Sm, Tb, and Er were prepared by ball milling UI(THF), SmBr, or MI with three equivalents of K(HBPPrBH). M(HBPEtBH) with M = U and Nd were prepared similarly using K(HBPEtBH), and the complexes were purified by extraction and crystallization from EtO or CHCl.

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The design of facile synthetic routes to well-defined block copolymers (BCPs) from direct polymerization of one-pot comonomer mixtures, rather than traditional sequential additions, is both fundamentally and technologically important. Such synthetic methodologies often leverage relative monomer reactivity toward propagating species exclusively and therefore are rather limited in monomer scope and control over copolymer structure. The recently developed compounded sequence control (CSC) by Lewis pair polymerization (LPP) utilizes synergistically both thermodynamic () and kinetic () differentiation to precisely control BCP sequences and suppress tapering and misincorporation errors.

Quantifying the Influence of Covalent Metal-Ligand Bonding on Differing Reactivity of Trivalent Uranium and Lanthanide Complexes.

Qualitative differences in the reactivity of trivalent lanthanide and actinide complexes have long been attributed to differences in covalent metal-ligand bonding, but there are few examples where thermodynamic aspects of this relationship have been quantified, especially with U and in the absence of competing variables. Here we report a series of dimeric phosphinodiboranate complexes with trivalent f-metals that show how shorter-than-expected U-B distances indicative of increased covalency give rise to measurable differences in solution deoligomerization reactivity when compared to isostructural complexes with similarly sized lanthanides. These results, which are in excellent agreement with supporting DFT and QTAIM calculations, afford rare experimental evidence concerning the measured effect of variations in metal-ligand covalency on the reactivity of trivalent uranium and lanthanide complexes.

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates.

In this Forum Article, we review the development of chelating borohydride ligands called aminodiboranates (HBNRBH) and phosphinodiboranates (HBPRBH) for the synthesis of trivalent f-element complexes. The advantages and history of using mechanochemistry to prepare molecular borohydride complexes are described along with new results demonstrating the mechanochemical synthesis of M(HBPBuBH), where M = U, Nd, Tb, Er, and Lu (-). Multinuclear NMR, IR, and single-crystal X-ray diffraction data are reported for - alongside complementary density functional theory calculations to reveal differences in their structure and reactivity with and without tetrahydrofuran.