Reactions of 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene with 1,2-C6H4(SiMe2)(2)Pt(PPh3)(2) and Pt(CH2=CH2)(PPh3)(2). X-ray structure determination of resulting double silylated compounds and platinum-alkyne complexes

The platinum complex of 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene (1), [(Ph3P)(2)Pt](2)[1], was synthesized quantitatively by the reaction of 1 with Pt(CH2=CH2)(PPh3)(2). The reaction of 1 with 1,2-C6H4(SiMe2)(2)Pt(PPh3)(2) gave 5,5,10,10,15,15,20,20-octamethyl- 5,10,15,20-tetrahydro-5,10,15,20-tetrasiladibenzo[b,n]tetraphenylene ([C6H4(SiMe2)(2)](2)(C16H8)) and [(Ph3P)(2)Pt][C6H4(SiMe2)(2)-C16H8] (C6H4(SiMe2)(2)C16H8 = 5,5,16,16-tetramethyl-5,16-dihydro-10,11-didehydro-5,16-disiladibenzo[a,e]naphtho[c]cyclooctene) as well as [(Ph3P)(2)Pt](2)[1]. The central eight-membered ring of [C6H4(SiMe2)(2)](2)(C16H8) has a typical tub-shaped structure, while that of [(Ph3P)(2)Pt](2)[1] is much less folded. The structure of [(Ph3P)(2)Pt][C6H4(SiMe2)(2)C16H8] lies between those of [C6H4(SiMe2)(2)](2)(C16H8) and [(Ph3P)(2)Pt](2)[1]. Crystal data: [(Ph3P)(2)Pt](2)[1]. 2toluene, C88H68P4Pt2.2C7H8, monoclinic, P2(1)/n, a = 16.369(2), b = 30.104(6), c=17.120(3) Angstrom,beta=102.69(1)degrees, V=8230(2) Angstrom(3), Z=4. [C6H4(SiMe2)(2)](2)(C16H8), C36H40Si4, monoclinic, P2(1)/c, a=18.421(2), b=11.131(1), c=16.444(1) Angstrom,beta=94.540(4)degrees, V=3361(4) Angstrom(3), Z=4. [(Ph3P)(2)Pt][C6H4(SiMe2)(2)C16H8], C62H54P2PtSi2, triclinic, <P(1)over bar>, a=13.538(2), b=17.244(4), c=12.510(3) Angstrom,alpha=111.10(2), beta=104.93(1), gamma=80.06(2)degrees, V-2622(1) Angstrom(3), Z=2. (C) 1997 Elsevier Science S.A.