Polymer crystal structure analysis

Lotz, B. Analysis and Observation of Polymer Crystal Structures at the Individual Stem Level. Vol. 180, pp. 17-44. 

Dorset, D. L. and Moss, B., Electron crystal structure analysis of linear polymers - an appraisal, in Polymer Characterization, Carver, C. D. (Ed.), Advances in Chemistry Series, Vol. 203, American Chemical Society, Washington, DC, 1983, 409-416. 

The results of this crystal structure analysis should then be viewed as having a reliability intermediate between standard single crystal structures where R is often 0.1, and crystalline polymer structures where only qualitative agreement is expected between observed and calculated structure factors. 

Cycloocta-2,4-dien-l-one (95) exists as an equilibrium mixture of the conformers 95a and 95b in solution, and conversion between these two enantiomeric forms is too fast to allow their isolation at room temperature. Photoreaction of 95 in pentane for 1 hr gives racemic 96 in 10% yield along with polymers. When a solution of (—)-ll and 95 was kept at room temperature for 12 h, a 3 2 inclusion complex of (—)-ll with 95a was obtained as colorless needles. Irradiation of the 3 2 complex of (—)-ll with 95a for 48 hr gave (—)-96 of 78% ee in 55% yield. X-ray crystal structure analysis is given in Ref. 51. 

An X-ray crystal structure analysis has shown that in the solid state LXIXa is a coordination polymer in which the tin atom is surrounded by one near chlorine atom, by two rather weakly bonded next-nearest-neighbor chlorine atoms, and by an asymmetrically pentahapto-bonded cyclopentadienyl ring, as indicated in Fig. 14. The perpendicular tin to ring distance (2.30 A) is significantly shorter than in stannocene the nearest tin-chlorine distance is even shorter in LXIXa (2.68 A) than in the solid state structure of SnCl2 (229). 

Reaction of a methanolic solution of copper(II) acetate and enantiomerically pure (/ )/(S)-methyl( )-4ethyl-2-oxazolidinylidene)cyanoacetate 64 leads to the coordinatively unsaturated CVsymmetric intermediates (R,Rj-65 and (S,S)-65, which are sterically shielded at one side by two ethyl groups. Therefore, in contrast to the 2D- and 3D-coordination polymers, coordination of (R,R)/(S,S)-65 with only one cyano donor is possible, resulting in the formation of polymers (/>)-oc1[Cu(Li )2] (P-66) and (M)-J[Cu(L5)2] (M)-66) (Scheme 24) ([166, 169, 170] for other chiral lD-coordination polymers of our group, see [171, 172]). The X-ray crystal structure analysis of polymer (P)-66 clearly proves a well-ordered infinite onedimensional architecture. The central copper atoms in (P)- [Cu(L )2] CP-66) are almost tetragonal-pyramidally coordinated, and in contrast to the 2D- and... 

Consequently, the mononuclear building blocks (S,S)-65 were obtained starting from (5S)-64. which during crystallization from chloroform afforded left-handed helical lD-coordination polymer (M)-fxJ Cu(L v)2 (M-66). The structure of (M)-66 was determined by X-ray crystal structure analysis (Fig. 24). In conclusion, it is demonstrated that stereogenic centers of ligands may induce stereospecifically helicity to lD-coordination polymers. Thus (R)-64 gives rise to (P)-66 and (S)-64 to mirror image (M)-66 [166, 169-172],... 

The second example, BPG-1, is a case of limited reactivity. The crystal structure analysis was carried out using a crystal containing only 35 percent polymer The quality of the data clearly does not allow to draw conclusions on the electronic structure of the polymer chain. 

Thirty years later, we discovered the topochemical polymerization of various 1,3-diene monomers giving a highly stereoregular polymer in the form of polymer crystals. When ethyl (Z,Z)-muconatc was photoirradiated in the crystalline state, a tritactic polymer was produced [18, 19], in contrast to the formation of an atactic polymer by conventional radical polymerization in an isotropic state. Thereafter, comprehensive investigation was carried out, for example, the design of monomers, the crystal structure analysis of monomers and polymers, and polymerization reactivity control, in order to reveal the features of the polymerization of 1,3-diene monomers [20-23], Eventually, it was revealed that the solid-state photoreaction... 

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