A series of group 14 metalloles, from silole to stannole, together with cyclopentadiene, having two thienyl groups at the 2,5-positions, have been prepared. Their crystal structures, UV−vis absorption and fluorescence spectra, and cyclic voltammograms have been determined. Theoretical calculations on their electronic structures have also been carried out. On the basis of these experimental and theoretical results, we compared their properties and electronic structures. The group 14 metallole derivatives from silole to stannole have essentially the same electronic structures and, thereby, comparable photophysical properties to each other, while significant differences exist between the cyclopentadiene and silole derivatives. The central group 14 elements, silicon, germanium, and tin, of the metalloles affect the LUMO energy levels of the π-electronic systems to almost the same extent through σ*−π* conjugation.

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Functionalization of octavinylsilsesquioxane (Vi(8)T(8), 1) by two reactions catalyzed by ruthenium complexes is reported: a silylative coupling reaction catalyzed by [RuHCl(CO)(PCy(3))(2)] (I) and cross-metathesis catalyzed by first- (II) and second-generation (III) Grubbs' catalysts. The two reactions of 1 with styrene take place highly regio- and stereoselectively (the X-ray structure of the product 2 has also been obtained); the cross-metathesis of 1-hexene and allyltrimethylsilane occurs quite effectively, whereas the silylative coupling with these compounds gives a mixture of isomers. Functionalization of 1 with heteroatom-substituted vinyl derivatives (Si, O, N) by silylative coupling reaction has been found to be highly efficient, but cross-metathesis appears to be the more effective method for the synthesis of S-substituted vinyl-silsesquioxane.

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Symmetrical 1,1-bis(silyl)ethenes have been easily prepared via ruthenium complex-catalyzed silylative coupling cyclization of 1,2-bis(dimethylvinylsiloxy)ethane to give 2,2,4,4-tetramethyl-3-methylene-1,5-dioxa-2,4-disilacycloheptane with excellent selectivity and good yield, followed by its reaction with Grignard reagents. The cyclic product can also be effectively transformed into cyclic carbosiloxane, 2,2,4,4,6,6,8,8-octamethyl-3,7-dimethylene-1,5-dioxa-2,4,6,8-tetrasilacyclooctane.

A new type of functionalization of cyclosiloxane and cyclosilazane is reported. Commercially available vinyl-substituted cyclosiloxane and cyclosilazane can be converted chemo-and regioselectively to styryl-and β-alkoxyvinyl-substituted derivatives via respective silylative coupling reactions with styrene and vinyl alkyl ethers catalyzed by RuHCl(CO)(PCy 3 ) 2 . The obtained cis-tristyrylcyclotrisiloxane showed a unique arrangement of the three styryl groups through face-to-face and side-by-side π-π interactions. Pd-catalyzed Hiyama coupling reaction of synthesized β-n-butoxyvinyl-substituted cyclosiloxane with iodobenzene was also performed to afford β-n-butoxystyrene regioselectively.

The highly stereo- and regioselective reaction of 1,3,5-tris(dimethylvinylsilyl)benzene (1) with p-substituted styrenes, p-XC6H4CHCH2, where X = H (2), Cl (3), Br (4), vinyl (5), catalyzed by RuHCl(CO)(PCy3)2 (I) appeared to be an efficient basis for new starburst compounds involving silylene−vinylene−arylene sequences. Attempts were made to synthesize the first generation of dendrimer (12), based on 1 as a core, via two methods:  direct silylative coupling of 1,3,5-tris[dimethyl(4-vinylstyryl)silyl]benzene (5) with 1, which gave a mixture of oligomers containing the SiCHCHSi structure, and successfully via silylation of 5 with vinylsilyl-3,5-bis(isopropoxysilyl)benzene (10) followed by vinylation with Grignard reagent. Additionally, the double silylation of DVB with 10 followed by vinylation allowed the synthesis of an analogous starburst compound (14), which can be a new core for analogous dendritic compounds.

Dedicated to Professor Julian Chojnowski on the occasion of his 70 th birthday in recognition of his significant contribution to organosilicon polymer chemistry.Abstract: Stereoregular trans-arylene-silylene-vinylene polymers of M w ¼ 13100 -34800 and PDI ¼ 1.6 -2.9 of the general formulasSiMe 2 À and À Me 2 SiC 6 H 4 -C 6 H 4 SiMe 2 À ) (19, 20, 21) have been effectively synthesized via silylative coupling (SC) homopolycondensation of bis(vinyldimethylsilyl)arenes (10, 12, 14) and cross-polycondensation of 4-(vinyldimethylsilyl)styrene (11) as well as cross-copolycondensation of bis(vinyldimethylsilyl)arenes (10, 12 and 14) with 1,4-divinylbenzene (9) catalyzed by [RuH(Cl)(CO) (PCy 3 ) 2 ] (7). Such highly stereoregular products cannot be synthesized via ADMET polycondensation or ring opening metathesis ROM or polyaddition of hydridosilanes to acetylenes.