Nickel-Catalyzed Cyclopolymerization of Hexyl- and Phenylsilanes

Abstract

Tables, figures, and a CIF file giving crystallographic data for 1, NMR and IR spectra for poly-I, poly-II, 1, and 2, and additional polymerization data. This material is available free of charge via the Internet at http://pubs.acs.org.

Tetramer and Polymer of 2,7-Dialkoxy-9H-9-silafluorene Composed of Si Backbone and π-Stacked Biphenylene Groups

“…The product does not contain cyclic polysilane molecules, although the polymerization of phenylsilane formed the cyclic molecules. 7 The linear structure is attributed to all-trans conformation of the Si atoms induced by π-stacking interaction of the biphenylene groups, as observed in the tetramer. UV absorption and fluorescence spectra of 1a, 3a, and 5a (M n = 3250, n = 10) in THF are shown in Figure 5.…”

“…Braddock-Wilking reported that reaction of silafluorene with [PtMe 2 (dppe)] (dppe: 1,2-bis(diphenylphosphino)ethane) produced the tetrasilaplatinacyclopentane via SiSi and SiPt bond formations, 6 while a Pd analogue was prepared by our group with a similar procedure. 7 We synthesized tetragermaplatinacyclopentanes and succeeded in preparing the tetragermanes from the complexes. 8 Tetrasilafluorene, similarly prepared, would provide useful information on the structures of the polymer as the model compound.…”

“…7 The former signal of 2a with a larger J PtSi value (716 Hz) than the latter (141 Hz) is assigned as Pt-bonded Si atoms. (Figure 3).…”

Hydrogenolysis of Polysilanes Catalyzed by Low‐Valent Nickel Complexes

“…Notably, the dinuclear Ni I hydride A (Figure b) dehydrogenates primary silanes to give polysilanes . Also, the related zerovalent [Ni(dmpe) 2 ] [dmpe=1,2‐bis(dimethylphosphino)ethane] produces linear polysilanes selectively . The principle of microscopic reversibility suggests that the opposite reaction, namely the catalytic hydrogenation of Si−Si bonds, may be possible (Figure a, eq.…”

Nickel(0)-Catalyzed Polycondensation of Silafluorene: Control over Molecular Weight and Polymer Growth Mechanism

“…All these polymerizations are step-growth polymerizations and are expected to produce polymers with a wider polydispersity (theoretically: M w / M n > 2) than chain-growth polymerizations . Previous reports showed that Ni catalysts such as a Ni/PPh 3 mixture, a methylnickel complex with indenyl and PR 3 ligands, [(dippe)­Ni­(μ-H)] 2 (dippe = 1,2-bis­(diisopropylphosphino)­ethane), and [Ni­(dmpe) 2 ] (dmpe = 1,2-bis­(dimethylphosphino)­ethane) promote the polymerization of primary or secondary silanes to yield linear and/or cyclic polymers, while our group discovered that [Ni­(dmpe) 2 ] is able to catalyze the polymerization of a 9 H -9-silafluorene. , This paper reports the unusual characteristics of this reaction, which provide control over the molecular weight of the polymer and over the polymer growth mechanism.…”