Synthesis of silanes with more than three silicon atoms are disclosed (i.e., (SinH(2n+2) with n=4-100). More particularly, the disclosed synthesis methods tune and optimize the isomer ratio by selection of process parameters such as temperature, residence time, and the relative amount of starting compounds, as well as selection of proper catalyst. The disclosed synthesis methods allow facile preparation of silanes containing more than three silicon atoms and particularly, the silanes containing preferably one major isomer. The pure isomers and isomer enriched mixtures are prepared by catalytic transformation of silane (SiH4), disilane (Si2H6), trisilane (Si3H8), and mixtures thereof.