A Robust, Divalent, Phosphaza-bicyclo[2.2.2]octane Connector Provides Access to Cage-Dense Inorganic Polymers and Networks.

While polymers containing chain or ring motifs in their backbone are ubiquitous, those containing well-defined molecular cages are very rare and essentially unknown for the inorganic elements. We report that a rigid and dinucleophilic cage (PNSiMe3)2(NMe)6, which is chemically robust and accessible on a multi-gram scale from commercial precursors, serves as a linear and divalent connector that forms cage-dense inorganic materials. Reaction of the cage with various ditopic P(III) dihalide comonomers proceeded via Me3SiCl elimination to give high molecular weight (30 000-70 000 g mol-1), solution-processable polymers that form free-standing films. The end groups of the polymers could be tuned to engender orthogonal reactivity and form block copolymers. Networked cage-dense materials could be accessed by using PCl3 as a tritopic P(III) linker. Detailed mechanistic studies implicate a stepwise polycondensation that proceeds via phosphino-phosphonium ion intermediates, prior to Me3SiCl loss. Thus, metathesis between the dinucleophilic cage and polyhalides represents a general strategy to making cage-dense polymers, setting the stage for systematically understanding the consequences of the three-dimensional microstructure on macroscopic material properties.

B(C6 F5 )3 -Catalyzed E-Selective Isomerization of Alkenes.

Herein, we report the B(C6 F5 )3 -catalyzed E-selective isomerization of alkenes. The transition-metal-free method is applicable across a diverse array of readily accessible substrates, giving access to a broad range of synthetically useful products containing versatile stereodefined internal alkenes. The reaction mechanism was investigated by using synthetic and computational methods.

Iron-Catalyzed H/D Exchange of Primary Silanes, Secondary Silanes, and Tertiary Siloxanes.

A synthetic study into the catalytic hydrogen/deuterium (H/D) exchange of 1° silanes, 2° silanes, and 3° siloxanes is presented, facilitated by iron-ß-diketiminato complexes (1a and 1b). Near-complete H/D exchange is observed for a variety of aryl- and alkyl-containing hydrosilanes and hydrosiloxanes. The reaction tolerates alternative hydride source pinacolborane (HBpin), with quantitative H/D exchange. A synthetic and density functional theory (DFT) investigation suggests that a monomeric iron-deuteride is responsible for the H/D exchange.