Zigzag polymers

Figure 8.1. (a) Spherulites growing in a thin film of isotactic polystyrene, seen by optical microscopy with crossed polars (from Bassett 1981, after Keith 196.3). (b) A common sequence of forms leading to sphertililic growth (after Bassett 1981). The fibres consist of zigzag polymer chains. 

The heteroatom cy clopentadienyl analog 1,4,2-P2 SbC2 Bu 2 has been coordinated to Tl(l) via equation (2), producing zigzag polymer (2). Thallium coordination has played an important role in crystallographic characterization of metal-fullerene complexes, providing the first structurally characterized pentahapto metal complexes of Ceo (3) and C70 (4). The key to the formation of these monothallium(l) compounds was the arylation of the fullerenes. Methylated Ceo forms a thallium complex as well. ... 

Manganese is presently absent from this family. Our attempts to make an Mn wheel similar to the cobalt and nickel wheels led to a one-dimensional polymer [Mn2(chp)2(02CMe)2(Me0H)2] [52]. There is in this structure curvature within each trinuclear unit, however, in neighbouring units the structure curves in opposite directions, leading to a zigzag polymer rather than a wheel. There must be a fine balance between these two alternative structures. 

Polymer 128 is built upon dppb and forms a zigzag polymer as demonstrated by X-ray studies, and supports the trend where an even number of methylenes in the chain promotes such a structure.115 The use of dppp leads to a cyclic oligomer (129). Dynamic 31P NMR investigations and mass-spectrometry analyses demonstrate the presence of equilibrium between cyclic oligomers and polymers. 

Some organotin carboxylates have structures totally different from those just discussed. For example, Bu2Sn(OOC6H4Br-2)2 is a weakly bridged dimer [497], whereas di-u-butyltin cyclobutane-dicarboxylate, Bu 2Sn(OOC)2C4H6, forms a zigzag polymer [498]. In both compounds tin is six-coordinate octahedral. 

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