Syntheses, Structures, and Reactivity of Radial Oligocyclopentadienyl Metal Complexes: Penta(ferrocenyl)cyclopentadienyl and Congeners

Abstract

“Supra”Cp: Fivefold Negishi coupling of pentaiodocymantrene resulted in radial oligocyclopentadienyl metal complexes (see scheme). These complexes show fascinating conformational and chemical behavior, including MM and CpCp bond formation and the liberation of the novel supraligand penta(ferrocenyl)cyclopentadiene. dba=dibenzylideneacetone.

Hexaferrocenylbenzene

“…8 The most highly ferrocenylated benzenes are dimethyl 1,2,3,4-tetraferrocenylphthalate 1a and 1,2,4,5-tetraferrocenylbenzene, 9 neither one of which has been structurally characterized, although a cycloheptatrienylvanadium analog of the latter has. 10 We have reported recently the five-fold metallacyclopentadienylation of C 5 I 5 Mn(CO) 3 using Negishi conditions, 11 the success of which encouraged us to extend this method to the synthesis of the title compound, despite the anticipated considerably increased steric crowding around the sixfold symmetric benzene core.…”

Synthesis, characterization and reactivity studies of the new compound [Os3(CO)9(μ3-η2,η3,η3-{C5H5FeC5H3CCC(S)C(Fc)CHO}]

“…For example, the synthesis of the compounds [M(CO) 3 (g 5 -C 5 H 4 R)] (M = Tc, Re; R = ketone, esther, amide) [11] has been achieved by reaction of C 5 H 5 FeC 5 H 4 R with MO 4 À (M = Tc, Re) in the presence of CrCl 3 and Cr(CO) 6 , as a consequence of the loss of a Fe(g 5 -C 5 H 5 ) fragment and the transference of the C 5 H 4 R ligand to the technetium or rhenium atom. Also, it has been reported the loss of one or two Fe(g 5 -C 5 H 5 ) fragments in the compound [Mn(CO) 3 (g 5 -C 5 R 5 )] (R = C 5 H 4 FeC 5 H 5 ) [12]. In addition to the loss of the Fe(g 5 -C 5 H 5 ) fragment, the formation of compound [Os 3 (CO) 9 (l 3 -g 2 ,g 3 ,g 3 -{C 5 H 4 -CCC(S)C(Fc)CHO}] 5 implies as well the protonation of the remaining C 5 H 3 ring, probably due to some moisture.…”

Combining Cobalt‐Assisted Alkyne Cyclotrimerization and Ring Formation through C–H Bond Activation: A “One‐Pot” Approach to Complex Multimetallic Structures

“…The crowded nature of the sterically demanding ferrocenyl groups at the respective ring systems is highlighted, for example, by distortion of the cyclic unit, as demonstrated for Fc 6 C 6 by single‐crystal X‐ray diffraction analysis 2. In the case of Fc 4 C 4 NPh, Fc 6 C 6 and [Mn(η 5 ‐Fc 5 C 5 )(CO) 3 ]3a rotation barriers for the individual ferrocenyl groups have been determined 2,3a,5. The multiple ferrocenyl units within perferrocenylated cycles and heterocycles additionally allow the investigation of their electrochemical behavior and electron‐transfer properties among the ring systems and between the ferrocenyl/ferrocenium units within a partly oxidized mixed‐valent oxidation state, that is, [Fc 4 C 4 NPh] n + ( n = 1, 2, 3).…”