Acepentalenediide

In view of the high purity and thermal stability of dilithium acepentalenediide 32 -2Li+ [48], it is the most feasible precursor of other stable acepentalene metal derivatives and... 

A more versatile approach to 4,7-disubstituted dihydroacepentalenes 65 is via the stable acepentalene dianion 64 as an easily accessible intermediate. Dipotassium acepentalenediide 64 can be obtained in virtually quantitative yield by treatment of triquinacene 10 with the superbasic mixture of potassium f-pent-oxide and butyllithium [or even better potassium f-butoxide, butyllithium and tetramethylethylenediamine (TMEDA)] in hexane, the so-called Lochmann-Schlosser base (Scheme 15) [62, 63]. Mechanistically this transformation has... 

Dilithium Acepentalenediide and Other Metal Complexes of Acepentalene... 

In the crystal the compound forms dimers consisting of two bowl-shaped CioHe dianions with the convex surfaces facing each other (Figure 7.6) Two DME-solvated lithium ions are sandwiched between these convex surfaces, whereas other two [Li(DME)]+ cations are located above the concave surfaces of the bowlshaped acepentalenediide dianions. In all cases the type of interaction between lithium and the hydrocarbon ligand is coordination. 

While some complexes of dihydroacepentalene derivatives have been reported some time ago [178-180], metal complexes of the unstable acepentalene (137), although they were the subject of DFT calculations [181], are still elusive. The acepentalene dianion (138) was obtained as its lithium salt in pure form by treatment of triquinacene (147) with BuLi/KOtBu/TMEDA giving 138 as its impure potassium salt, which was trapped with MegSnCl. The l,7-bis(trimethylstaimyl)-4,7-dihydroacepentalene (148) obtained was then treated with methyllithium, affording pure dilithium acepentalenediide (138-2Li+) (Scheme 10.52) [152]. 

---