Ring-Opening Polymerisation of Low-Strain Nickelocenophanes: Synthesis and Magnetic Properties of Polynickelocenes with Carbon and Silicon Main Chain Spacers |
| |
| Authors: | Rebekah L N Hailes Dr Rebecca A Musgrave Dr Alexander F R Kilpatrick Dr Andrew D Russell Dr George R Whittell Prof Dermot O'Hare Prof Ian Manners |
| |
| Institution: | 1. School of Chemistry, University of Bristol, Bristol, BS8 1TS UK;2. Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Rd, Oxford, OX1 3TA UK |
| |
| Abstract: | Polymetallocenes based on ferrocene, and to a lesser extent cobaltocene, have been well-studied, whereas analogous systems based on nickelocene are virtually unexplored. It has been previously shown that poly(nickelocenylpropylene) Ni(η5-C5H4)2(CH2)3]n is formed as a mixture of cyclic ( 6 x ) and linear ( 7 ) components by the reversible ring-opening polymerisation (ROP) of tricarba3]nickelocenophane Ni(η5-C5H4)2(CH2)3] ( 5 ). Herein the generality of this approach to main-chain polynickelocenes is demonstrated and the ROP of tetracarba4]nickelocenophane Ni(η5-C5H4)2(CH2)4] ( 8 ), and disila2]nickelocenophane Ni(η5-C5H4)2(SiMe2)2] ( 12 ) is described, to yield predominantly insoluble homopolymers poly(nickelocenylbutylene) Ni(η5-C5H4)2(CH2)4]n ( 13 ) and poly(tetramethyldisilylnickelocene) Ni(η5-C5H4)2(SiMe2)2]n ( 14 ), respectively. The ROP of 8 and 12 was also found to be reversible at elevated temperature. To access soluble high molar mass materials, copolymerisations of 5 , 8 , and 12 were performed. Superconducting quantum interference device (SQUID) magnetometry measurements of 13 and 14 indicated that these homopolymers behave as simple paramagnets at temperatures greater than 50 K, with significant antiferromagnetic coupling that is notably larger in carbon-bridged 6 x /7 and 13 compared to the disilyl-bridged 14 . However, the behaviour of these polynickelocenes deviates substantially from the Curie–Weiss law at low temperatures due to considerable zero-field splitting. |
| |
| Keywords: | copolymerization magnetic polymers metallopolymers ring-opening polymerization |
|
|
