Architectural Editing of Polyesters and Polyurethanes via Palladium(II)-Catalyzed [3,3]-Sigmatropic Oxo-Rearrangements.

Architecture underlies the thermomechanical properties of polymers. Yet, few strategies are available to tune a polymer's architecture after it is prepared without altering its chemical composition. The ability to edit the architecture of a polymer would dramatically expand the accessible architecture-property space of polymeric materials.

Mechanistic study of pyrazole synthesis oxidation-induced N-N coupling of diazatitanacycles.

Metal-mediated inner-sphere N-N coupling is an uncommon route to N-N bond formation. Herein, we report a mechanistic study of pyrazole formation oxidation-induced N-N coupling of diazatitanacycles. In TEMPO oxidation reactions, the first of two oxidations is rate limiting and TEMPO coordination to Ti is critical for reactivity.

Bonding and Reactivity of d Transition Metal Imido Complexes Encoded in Their N NMR Signatures.

Terminal imido complexes containing metal-nitrogen multiple bonds have been widely used in organometallic chemistry and homogeneous catalysis. The role of terminal imido ligands spans from reactive sites to spectator motifs, largely depending on the nature of the metal center and its specific coordination sphere. Aiming at identifying reactivity descriptors for M-N multiple bonds, we herein explore solid-state N NMR spectroscopy (ssNMR) on early transition metal terminal imido complexes augmented by computational studies and show that the asymmetry parameter, κ (skew, 1 ≥ κ ≥ -1), readily available from experiments or calculations, is diagnostic for the reactivity of M-N multiple bonds in imido complexes.

Sustainable Copolymer Synthesis from Carbon Dioxide and Butadiene.

Carbon dioxide (CO) has long been recognized as an ideal C1 feedstock comonomer for producing sustainable materials because it is renewable, abundant, and cost-effective. However, activating CO presents a significant challenge because it is highly oxidized and stable. A CO/butadiene-derived δ-valerolactone (EVP), generated via palladium-catalyzed telomerization between CO and butadiene, has emerged as an attractive intermediate for producing sustainable copolymers from CO and butadiene.

Evaluation of Tungsten Catalysis among Early Transition Metals for -Aryl-2,3,4,5-tetraarylpyrrole Synthesis: Modular Access to N-Doped π-Conjugated Material Precursors.

Low-valent tungsten species generated from WCl and ,-bis(trimethylsilyl)-2,5-dimethyldihydropyrazine (-Me-DHP) promotes the catalytic formation of -phenyl-2,3,4,5-tetraarylpyrroles from diarylacetylenes and azobenzene (). An initial catalyst activation process is a three-electron reduction of WCl with -Me-DHP to afford transient 'WCl' species. Catalytically active bis(imido)tungsten(VI) species via successive one-electron reduction and N═N bond cleavage of was revealed by isolating W(═NPh)Cl(PMePh) from imidotungsten(V) trichloride and in the presence of PMePh.