2 reacts with fluorosilanes, e.g. with F3SiC6H5, in the molar ratio 1 2 to give disubstituted ("monomeric") products containing an eight-membered ring. ['] Reaction in the molar ratio 1 : 1 leads to a derivative 4 of the novel bicyclic system 1,3,5,7-tetraaza-2,4,6,8,9-pentasilabicyclo[3.3.l]nonane (Fig. ).l9] The N2-N4-Si2-Si3 and N2-N4-Si4-Si 1 planes of the two six-membered rings are inclined towards each other. N2, Sil, N1, Si4, and N4 are coplanar, whereas N3 of the second six-membered ring is bent towards the bridging atom Si5, so that N3, Si2, N4, Si5, N2, and Si3 form a tub-shaped moiety. Fig. 2. Molecular structure of 3 in the crystal. Selected bond lengths [pm] and angles ["I: Nl-SiI 174.7(15), SiI-N2 173.5(7), N2-Si3 175.3(7), Si3-N3 172.8(13), N3-Si2 172.8(7), Si2-N4 174.3(5), N4-Si4 175.8(8), Si4-NI 171.8( ), N2-Si5 173.2(13), Si5-N4 172.4(12), Si5-Fl 160.4(5); Sil-Nl-Si4 133.9(5), Si2-N3-Si3 127.1(5), Sil-N2-Si3 131.2(5), Sil-N2-SiS lll.5(6), Si3-N2-Si5 107.5(4), Si2-N4-Si4 126.4(5), Si2-N4-Si5 108.9(6), Si4-N4-SiS I10.8(4). N2-Si5-N4 106.1(5).
Experimental
A solution of l b (0.01 mol) in hexane (100 mL) was treated with 0.02 mol of nC,H,Li ( IS% in hexane) in a three-necked flask fitted with an internal thermometer. For complete cleavage of butane, the sludge was heated under reflux for 2 h. T H F was then added until the lithium salt dissolved at the boiling temperature. 2 crystallized out at room temperature. For the synthesis of 3 and 4 the solution of 2 was cooled to -20Β°C. After slow dropwise addition of 0.02 mol and 0.01 mol of PhSiF,, respectively, the solutions were warmed to room temperature for 2 h (I9F-NMR monitoring). After removal of lithium fluoride, 3 and 4 crystallized out from the solutions: yields 4.5 g (92%) 2, 4.8 g (84%) 3, 2.6 g (63%) 4.