Synthesis, structure, and reactivity of disilanes containing one neutral [4+2]-coordinate silicon center

[4+2]-Coordinate disilanes containing two 8-dimethylamino-1-naphthyl (8-Me2N-1-Np) groups on the same silicon atom, (8-Me2N-1-Np)2XSi-SiMe3, where X=F, OH, OEt, and H, are prepared. The X-ray structures of the two derivatives, X=F and OH, show that one of the coordinated dimethylamino groups is anti to the electronegative X group, while the other is anti to the trimethylsilyl group. The [4+2]-coordinate disilanes (X=F or OEt) are found to be thermally stable under these conditions such that the corresponding [4+1]-coordinate disilanes (8-Me2N-1-Np)XMeSi-SiMePh2 (X=F or OEt) readily undergo degradation. In the presence of Pd(PPh3)4 as a catalyst, the [4+2]-coordinate disilane (X=F) undergoes degradation to generate naphthylsilane (8-Me2N-1-Np)-SiMe3, the reaction pathway being different from that of the [4+1]-coordinate disilane (X=F) which affords the fluorosilane, F-SiMePh2.