Dilithioferrocene-tmeda

The first reported examples, Fe(C5H4)2SiPh2 (47) and the spiro compound Si(H4C5FeC5H4)2 (52)131, were synthesized by a classical procedure (see Section II) via the reaction of dilithioferrocene-TMEDA with diphenyldichlorosilane and tetrachlorosilane, respectively. The other members in this class were prepared analogously or via the reaction of ferrous chloride with the corresponding dilithiated bis(cyclopentadienyl)dimethylsilane11°,132 134. 

Moran et al. have also reported the preparation of hyperbranched ferrocenyl. S7-based polymers (Figure 8.1). The construction of ferrocenyl —silicon polymers 40 and 41 was effected by the reaction of dilithioferrocene-TMEDA with the tetrachlorosilane 35 (see Scheme 8.10) and the Pt-mediated hydrosilylation of l,l -divinylferrocene with tetrasilyl-hydride 38. The 3-dimensional motif exhibited by hyperbranched polymers 40 and 41 is analogous to that depicted by the ferrocenyl — silicon network structures 38,43 42 and 43 (Figure 8.2). 

Early attempts to prepare polymers of general structure 11 focused on reactions of dilithioferrocene-tmeda and appropriate dihaloorganosilanes. For example, in the late 1960s low molecular weight poly(ferrocenylsi-lanes) 11 (jc = I, R = Me or Ph) were prepared via condensation routes... 

Condensation approaches to ferrocene/organosilane polymers have been extended to the synthesis of low molecular weight materials 11 (jc = 6, R = Me) with M 3500 from the reaction of dilithioferrocene-tmeda with the dichlorohexasilane Cl(SiMe2)6Cl (39). These polymers were shown to possess electrical conductivities in the range of 10" -10 S/cm... 

Much better defined, moderate molecular weight (M 8900) poly(ferro-cenylphosphines) 24 were prepared by Seyferth and co-workers via the polycondensation reaction of l,r-dilithioferrocene tmeda with PhPCb in dimethoxyethane at 25°C followed by conversion of the proposed Cp-Li and P-CI end groups of the condensation polymer 23 to Cp-H and P-OH or P-Ph, respectively (73). Furthermore, under certain carefully con-... 

Preparation of fl -dilithioferrocene-TMEDA [209] The whole procedure is carried out under an inert, dry atmosphere with freshly dried solvents stored under inert gas using standard Schlenk line techniques. n-Butyllithium (160 mL, 2.3 M) in -hexane), was added to 30 g (0.16 mol) of ferrocene (recrystallized from hexane), followed by 30 mL (0.20 mol) of N.N,N N -tetramethylethylenediamine (TMEDA, distilled from BaO under argon). The reaction was allowed to proceed overnight, ca. 16 h. The product was filtered off, washed with 3 x 100 mL of hexane, and dried imder vacuum. This gave 44.9 g (92% yield) of an orange pyrophoric powder, sensitive to moisture. The compound was recrystallized from THE at -40 °C. 

A typical early route to polyferrocenylenes (40) with M < 5000 involved polycondensation processes such as the recombination of ferrocene radicals generated via the thermolysis of ferrocene in the presence of peroxides. However, these materials have been foimd to possess other fragments such as CH2 and O in the main chain (128,129). More structurally well-defined polyferrocenylenes (40) (Mn < 4000) have been prepared (130) via the condensation reaction of 1,1-dilithioferrocene TMEDA (tetramethylethylenediamine) with 1,1-diiodoferrocene and, significantly, the reaction of l,l -dihaloferrocenes with magnesium (eq. 30) has been shown to afford low molecular weight (M = 4600 for soluble fractions) materials with appreciable crystallinity (131). In the latter case, oxidation with 7,7,8,8-tetracyanoquinodimethane (TCNQ) afforded doped polymers that were delocalized on the Mossbauer time scale (ca 10 s) at room temperature and which possessed electrical conductivities of up to 10 S/cm. 

Recently, Tanaka et al. have reported the synthesis and conducting properties of poly[l,6-(dodecamethyl-hexasilanylene)-l,l -ferrocenylene] (42) [64]. Ferro-cenylene-hexasilanylene poljmier 42 can be obtained by the reaction of a dilithioferrocene-TMEDA complex with 1,6-dichlorododecamethylhexasilane in toluene. 

The dilithioferrocene-TMEDA complex is a bright yellow powder with very low solubility in toluene, Et20, and THE. The product can be stored for extended periods at room temperature under a nitrogen atmosphere. In our hands, no decomposition is observed after 12 months in a glove box. The complex is highly pyrophoric when exposed to air, however, and must be handled with care. 

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