Synthesis, structure, and reactivity of 1,omega-bis(pseudo-pentacoordinated) 1,omega-difluoro-oligosilanes bearing 8-(dimethylamino)-1-naphthyl groups

1,omega-Bis[8-(dimethylamino)-1-naphthyl]-1,omega-difluorotrisilane 1 (omeg a = 3) and tetrasilane 2 (omega = 4) have been prepared. The X-ray crystall ography of dl-1 and meso-1 shows unsymmetrical structures having different coordination modes at the two terminal silicons. The unsymmetrical nature o f the structure of 1 can also be observed by solid state CP/MAS NMR spectro scopy. Trisilane 1 is thermochemically labile and undergoes facile degradat ion at 145 degrees C, but is photochemically stable under irradiation of it s benzene solution with a 6 W-low pressure mercury lamp, making a sharp con trast to the behavior of their tetracoordinate counterparts containing naph thyl groups which are thermochemically stable but photochemically active. T etrasilane 2 undergoes a Pd(0)-catalyzed alpha-elimination of a fluorosilan e moiety at the two pseudo-pentacoordinated silicon atoms to form the 1,2-d ifluorodisilane, which is trapped with diphenylacetylene as a double-silyla tion product. (C) 1999 Elsevier Science S.A. All rights reserved.