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The structure and reactivity of poly(methylenephosphine)s

University of British Columbia

The initiation and termination steps of the anionic polymerization of P=C bonds have been modeled. The initiation step was investigated through the stoichiometric reaction of MesP=CPh₂(1) with RL1 (R Me or n-Bu). In each case, the addition was highly regioselective with the formal attack of R at phosphorus to give the carbanion Li[Mes(R)P—CPh₂](R = Me (3a); n-Bu (3b)). To simulate the termination step, carbanions 3a and 3b were quenched in situ with various electrophiles: Mes(Me)P—CPh₂H (4a), Mes(n-Bu)P—CPh₂H (4b), Mes(Me)P—CPh₂Me (6a), Mes(Me)P—CPh₂—P(NEt₂)₂ (7a), Mes(Me)P—CPh₂—SiMe₂H (8a) and Mes(Me)P—CPh₂—SiMe₃ (9a). The first use of MALDI-TOF MS in the study of the products of RLi (R = Me, n-Bu) initiated oligomerization of 1 is reported. The detected linear products R[MesP(=O)-CPh₂]nH with R—P and C—H end-groups are consistent with a chain growth mechanism. The oligomerization was extended to other monomers (MesP=CPhAr, Ar = p-C₆H₄F or p-C₆H₄OMe). The results suggest oligomers undergo fragmentation during MALDI-TOF analysis. The thermal reactions of M(CO)₆ (M = W, Mo, Cr) with polymer n-Bu[MesP-CPh₂]nH (10) and its model compound 4a are reported. IR was primarily used to determine the success of metal coordination in the polymer. EDXISEM and GPC-LLS were used to determine metal content of the materials. Most metallation was modest (>10%), however, as much as 20% was attained with Mo. The phosphorus-containing polymer 10 was found to be an effective ligand for gold(l) to afford n-Bu[MesP(AuCl)—CPh₂]nH 11, a new class of macromolecule with high gold content. The prepared model compound MeMesP(AuCI)—CPh₂H 12 was characterized by X-ray crystallography and NMR spectroscopy. Block copolymers containing phosphorus atoms in the backbone were prepared and metallated with gold(l). The living polymerization of isoprene (I) and then phosphaalkene I affords block copolymers PIm-b-[MesP-CPh₂]n (13a: m = 308, n = 46; 13b: m = 222, n = 77). Treating PIm-b-[MesP-CPh₂]n with (tht)AuCI results in gold-containing macromolecules [Pl]mb MesP(AuCl)-CPh₂]n (14a and 14b). Upon dissolution in a polyisoprene selective solvent (n heptane), the metallated block copolymers assembled into micelles (14a: spherical; 14b: worm-like). The solution self-assemblies were examined by TEM and DLS.

Text

2010-04-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/24014

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/