Ring‐Opening Polymerisation of Low‐Strain Nickelocenophanes: Synthesis and Magnetic Properties of Polynickelocenes with Carbon and Silicon Main Chain Spacers
Bibliographic record
Abstract
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(η 5 ‐C 5 H 4 ) 2 (CH 2 ) 3 ] n is formed as a mixture of cyclic ( 6 x ) and linear ( 7 ) components by the reversible ring‐opening polymerisation (ROP) of tricarba[3]nickelocenophane [Ni(η 5 ‐C 5 H 4 ) 2 (CH 2 ) 3 ] ( 5 ). Herein the generality of this approach to main‐chain polynickelocenes is demonstrated and the ROP of tetracarba[4]nickelocenophane [Ni(η 5 ‐C 5 H 4 ) 2 (CH 2 ) 4 ] ( 8 ), and disila[2]nickelocenophane [Ni(η 5 ‐C 5 H 4 ) 2 (SiMe 2 ) 2 ] ( 12 ) is described, to yield predominantly insoluble homopolymers poly(nickelocenylbutylene) [Ni(η 5 ‐C 5 H 4 ) 2 (CH 2 ) 4 ] n ( 13 ) and poly(tetramethyldisilylnickelocene) [Ni(η 5 ‐C 5 H 4 ) 2 (SiMe 2 ) 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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".