Chemistry of 2,3-dihydro-2-metallaphenalenes. Part 2. Formation of [CHMMe2C(MMe3)C10H6]xvia base decomposition of [1,8-(Me3MCH2)2C10H6]y(M = Ge, x= 2–, y= 0; M = P, x= 0, y= 2+); crystal structures of the novel bis-ylide CHPMe2C(PMe3)C10H6 and of a distorted peri-ylide, 1-Me-8-(Me3PCH)C10H6

Abstract

Treatment of 1,8-(Me₃GeCH₂)₂C₁₀H₆, derived from a Grignard in situ trapping reaction, with Li(Me₂NCH₂CH₂NMe₂)Buⁿ in hexane yields the germanium heterocyclic dianion [[graphic omitted]H₆]^2–, characterized as its protonolysis product. Potassium hydride and [1,8-(Me₃PCH₂)₂C₁₀H₆]Cl₂ in tetrahydrofuran affords the novel bis-ylide H[graphic omitted]H₆, (4), and small amounts of the mono-ylide 1-Me-8-(Me₃PCH)C₁₀H₆, (5). The ring system in (4) is planar, the heteroatom excepted (0.50 Å deviation), with C_ylide–P to P–C_ylide to C_ylide–P distances of 1.742(4), 1.700(5), and 1.726(5)Å; cf. P–C_Meca. 1.8 and P–C_ylide 1.69(1)Å in (5). The aromatic rings in (5) are twisted, the ylide carbon, which is almost ‘co-planar’ with the adjacent ring, and peri-methyl carbon being skewed in opposite directions.