Selective Synthesis of 2,2,4,4-Tetrasilylpentasilane.

A new structural isomer of nonasilane, 2,2,4,4-tetrasilylpentasilane or (H3Si)3SiSiH2Si(SiH3)3, is formed in disproportionational condensation of neopentasilane. This reaction can be catalyzed by a freshly cleaned borosilicate surface, and the catalyzed reaction can have over 85% selectivity for this branched nonasilane near 100 °C. A synthetic method has been developed from this catalytic reaction for making 98 wt % 2,2,4,4-tetrasilylpentasilane. The high-purity 2,2,4,4-tetrasilylpentasilane has a workable shelf life in 316 stainless steel containers.