Ferrocene-containing Polymers. VIII. Polycondensation of N, N-Dimethylaminomethylferrocene with Ferrocene

Abstract

Based on previous investigations involving the self-condensation of the ferrocenyl Mannich base, N, N-dimethylaminomethylferrocene (I), the present paper describes the co-condensation of this Mannich base with ferrocene. The reactions are conducted in the melt phase in the presence of a ZnCl2/HCI catalyst system. The resulting polymeric products are soluble and partially fusible and have number-average molecular weights in the 500-4000 range (unfractionated). The polymers, exhibiting the idealized structure III, are closely related to the products of self-condensation (II), with recurring units composed of ferrocenylene and methylene groups and homoannular substitution predominating along the chain. Due to the presence of ferrocene, however, an additional termination stepis introduced into the overall reaction, leading to a reduced degree of polymerization. The considerable excess over the stoichiometric amount of ferrocene required to achieve this competitive termination and concomitant decrease in Mn suggests that pronounced inductive and hyperconjugative effects are operative in the ferrocenylene-methylene system, resulting in activation of the methylene-substituted ring. The isolation of the lowest homolog possible, diferrocenylmethane, lends further support to the proposed structure of the recurring unit. Spectroscopic evidence obtained on subfractionated material suggests the substitution pattern along the chain to be essentially the same as in the earlier described homocondensation polymers, which is consistent with the assumption of essentially like propagation mechanisms in both cases. A small degree of branching is also inferred from spectroscopic data.In a previous publication,1) the ZnC12/HC1-catalyzed formation of ferrocene-containing polymers from the ferrocenyl Mannich base, N, Ndimethylaminomethylferrocene (I), was described. The products of condensation were shown essentially to be composed of ferrocenylene-methylene recurring units, and the overall polymer structure was depicted, somewhat idealized, by the novolactype formula II. Each polymer molecule was believed to contain a double-bridged segment resulting from termination steps through selfsubstitution on the penultimate ferrocenylene group of the growing chain, much as proposed2) for the identical polycondensation product of hydroxymethylferrocene.In continuation of these earlier efforts, the present paper describes work on the polycondensation of the Mannich base in the presence of ferrocene, in which case essentially the same propagation sequence, but a different termination step, may be expected, leading to polymer III rather than II. Results and DiscussionAs in the case of homocondensation of I, the co-condensation of this Mannich base with ferrocene, summarized in Eq. 1, will proceed in several steps, the first of these1) being the formation of adduct IV. By stepwise ionization, with V occurring as successor species,3) complex IV will generate the metallocarbonium ion VIa (or VIb from polyhomologs of IV and V in an advanced stage of t...

Organometallic polymers I. Solution polymerization of α‐ferrocenylmethylcarbonium fluoborate

“…One can aSsume that the first growth stage represents the self-condensation of FMCF, when pairs of monomer units may react to give a dimer (11). In its most probable form (11), the dimer contains a heteroannularly disubstituted ferrocenylene unit, due to the deactivating effect of the positive carbon atom on the adjoining ring.…”

Metallocene Polymers. XVIII. Poly(ferrocenylphosphine oxides)

“…Crystallographic bond-length determinations in (2) should aid in resolving this bond order problem. earlier (30) been established, an appreciable population of homoannularly interlinked ferrocenylene units can safely be assumed. An examination of the area ratio of the unsubstituted to the substituted cyclopentadienyl ring proton signals in the PMR spectra of representative samples of (l), correcting for ferrocenyl end groups, in fact, permitted the conclusion that nearly one-third of all ferrocene units were of the homoannularly substituted type (with steric effects doubtlessly favoring the 1,3 disposition).…”