Higher Chain and Branched Organopolysilanes

Many kinds of longer chain and branched silanes with organic substituents are known. The principal reactions of the Si-Si bonding in these substances correspond with those which have been discussed for disilanes. 

The six-membered ring is found to be very stable, but it too may be cleaved  

Wurtz synthesis and similar coupling mechanisms have also been used in the preparation of higher silane derivates  

Kumada et al.359 prepared linear methylpolysilanes up to n = 12 by Wurtz synthesis from different chloromethyldisilanes and found by investigation of the physical constants that the melting points of the silanes up to n = 7 do not rise continuously but follow in a zigzag course since the polysilanes with an odd number of silicon atoms melt at a lower temperature, than those with an even number of silicon atoms, though this effect is less pronounced with higher n. 

Irradiation with UV (2537 A) causes decomposition of longer chains (n = 4-6) into Si3me8 and polymer products, presumably by a silylene mechanism31 

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