Fulvalene derivatives

Apart from thiolate ligands, S, Se or -containing fulvalene derivatives have been employed as electron donors in the synthesis of gold complexes. The combination of tetrathiafulvalene, TTF, with the gold complex bis(pyrazine-2,3-diselenolate)aurate... 

Various cross-conjugated enediynes undergo Bergman-type cycloaromatizations upon reduction with potassium metal, generating anions of fulvenes and fulvalene derivatives (Scheme l).6 Not all cross-conjugated enediynes yield cyclized dianions upon reduction some give uncyclized, Y-shaped, cross-conjugated dianions, whereas others apparently yield radical anions that either dimerize or persist as monomers. 

Photolysis of the fulvalene derivative, (fx,-ri -r] -C5H4C5H4)Ru2(CO)4, with trans-2-butene yields mono and disnbstituted species, (/l4-) -) -C5H4C5H4)Ru2(CO)3L and (/ x- ] - ] -C5H4C5H4)Ru2(CO)2L2, where L = 2-butene. Some rearrangement of the trans-2-butene to cis-2-butene was observed. In contrast, photolysis of (ft-) ... 

Reduction of Cp2ZrCl2 with 1.5equiv. of sodium amalgam affords the fulvalene complex CpZr(/r-Cl) 2(/r-C5H4-C5H4) 28.35 COMC(1995) summarized a number of phosphido, sulfide, imido, and alkyl complexes derived from 28. Cuenca and co-workers have since reported further investigations into the chemistry of 28, leading to new zirconium(iv) /(-imido. //-(r/2.r/2-N.N-hydrazido), and //-(r/ -C r/2-C,N-isocyanido) dinuclear fulvalene derivatives.36... 

A direct and, in some cases, more effective method to a mixed system yielding a single fulvalene derivative, is based on reaction of a l,3-dichalcogenole-2-iiimionium salt (97) with an appropriate Wittig-Horner reagent (96) as Scheme 20 demonstrates <89MI 314-01>. 

Mild oxidation of (84) gives the Re-Re bonded dimer of rhenocene (85), which further reacts upon warming to form other dimers, such as the fulvalene derivative (86). 

The transition temperatures T of the fulvalene derivatives are shown in Table 1. The abbreviations of the various molecular groups are listed in Table 2 and their chemical structures are depicted in Figure 1. Most of the T s are between 1 and 12 K. Several of the compounds only show superconductivity under pressure. 

A substantial number of fulvene and fulvalene derivatives have been prepared. The chemical properties of these molecules are those of reactive polyenes. The molecular geometry of dimethylfulvene has been examined by electron diffraction methods. Strong bond-length alteration indicative of a localized structure is found. ... 

Tobe reported that palladium-catalyzed ring-closure reaction of 200 provides l,l -biindenylidene 201 by a domino-Heck-type double cyclization in moderate yields (Scheme 6.53) [124]. The reaction is appHcable to the synthesis of fulvalene derivatives involving thiophene ring(s) 202 and 203 [125]. The (Z)-isomers of the... 

An overcrowded fulvalene derivative 211 based on a truxene core was also prepared by treatment of truxenetrione 212 with fluorenyl lithium and dehydration of the formed alcohol using thionyl chloride (Scheme 6.56) [128]. 

Shimizu and Hiyama [129] reported that the palladium-catalyzed double-cross-coupling reaction of 9-stannafluorenes 213 with 1,1-dihaloethylene 214 yields the dibenzofulvene 215 (Scheme 6.57a). The 9-staimafluorene 213, an equivalent of a 1,4-dimetalated reagent, is available from the corresponding 2,2 -dihalobiphenyls. The reaction was applied to the synthesis of the jt-extended fulvalene derivative 217 from 216. The former is a stable benzaimulated Chichibabin hydrocarbon possessing an open-shell diradical character (Scheme 6.57b) [130]. 

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