Phosphorus-bridged ferrocenophanes

It is also possible to form block co-polymers via the living anionic ROP of the phosphorus-bridged ferrocenophanes (Section 12.06.3.3.3). " Diblock co-polymers such as PI-/)-PFP 108 can be prepared by the sequential anionic polymerization of isoprene and ferrocenophane 107 (Scheme 10). These materials yield spherical micelles in -hexanes with an amorphous PFP core and a PI corona. The PI corona can be cross-linked via radical reactions to yield a permanently cross-linked shell, which retains its integrity even in good solvents for both blocks. With PFP block co-polymers the possibility of the coordination of various catalytically active transition metal moieties to the phosphorus centers may prove useful for catalysis and for materials science applications. 

Examples of organometallic polymers containing both phosphorus atoms and transition metals in the backbone include polyferrocenylphosphines 8 (and the corresponding phosphine sulfides 9), which are accessible via the thermal ROP of phosphorus-bridged [1] ferrocenophanes [16,17]. Polymers of this type have been previously prepared by condensation routes and the catalytic potential of some of their transition metal derivatives has already been noted [18]. Living anionic ROP of phosphorus-bridged [l]ferrocenophanes has recently been demonstrated and provides a route to block copolymers such as 10 (PI = poly-isoprene) [19] ... 

High molecular-weight mixed-metal polyferrocenes have been prepared by Miyoshi et al. via the photochemical ROP of phosphorus-bridged [l]ferrocenophanes containing organometallic units on the phosphorus ligand (Scheme 2.14).111... 

Homo- and block copolymers from phosphorus-bridged [l]ferrocenophanes were isolated from living anionic ring opening polymerizations.113 Scheme 2.15 shows preparation of borane adducts of poly(ferrocenylphosphine)s by thermal ROP or addition of BX3 (X = H, Cl).114... 

Scheme 2.16 displays the thermal ROP of a number of phosphorous-bridged ferrocenophanes, resulting in the isolation of phosphorus(III)- and (V)-containing polymers 59a-c.115 Reaction of poly(ferrocenylphosphines) 59a-c with elemental sulfur generated poly(ferrocenylphosphine sulfides) 60a-c. Polymers 60a-c could not be directly prepared from thermal ROP of phosphine sulfide-bridged ferrocenophanes due to partial decomposition of the products. However, ferro-cenophane 58a polymerized via anionic ROP and reacted with sulfur.116 The resultant polymers had Mn = 3600-32,000 for monomer-catalyst ratios that were varied from 11 1 to 100 1. 

Although early attempts to induce the anionic ROP of phosphorus-bridged [I]ferrocenophanes only generated a mixture... 

Polyferrocenylphenylphosphines 3.29, analogous to those previously synthesized by polycondensation routes (Section 3.2.2), have also been prepared by thermal ROP of phosphorus-bridged [l]ferrocenophanes 3.28 (Eq. 3.13) [72]. The solubility of the materials was observed to increase when the cyclopentadienyl rings were substituted with n-butyl or trimethylsUyl groups. Sulfurization was carried out in order to facilitate their characterization by GPC, as the polyferrocenylphosphine... 

Living anionic polymerization of phosphorus-bridged [l]-ferrocenophanes 494... 

In addition, phosphorus-bridged [l]ferrocenophanes such as 5 (R = Ph) and related species also polymerize th mally to yield poly(ferrocenylphosphines) such as... 

Gates DP (1997) The synthesis, structure, reactivity and polymerization behavior of boron- and sulfur-nitrogen-phosphorus heterocycles and highly strained chalcogen- and boron-bridged [1], ferrocenophanes. PhD thesis, University of Toronto... 

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