Highly Birefringent Cyanoaurate Coordination Polymers: The Effect of Polarizable C−X Bonds (X = Cl, Br)
Bibliographic record
Abstract
Four new coordination polymers, Mn(Clterpy)[Au(CN)(2)](2) (Clterpy = 4'-chloro-2,2';6',2''-terpyridine), Mn(Brterpy)[Au(CN)(2)](2) (Brterpy = 4'-bromo-2,2';6',2''-terpyridine), Pb(Clterpy)[Au(CN)(2)](2), and Pb(Brterpy)(mu-OH(2))(0.5)[Au(CN)(2)](2) were synthesized and structurally characterized, and their birefringence values were measured. The supramolecular structures of the two Mn(II) polymers are the same: they form one-dimensional (1D) chains of Mn(Xterpy)[Au(CN)(2)](2) units (X = Cl, Br), each having one bridging and one terminal Au(CN)(2)(-). The Pb(II) analogues form 1D polymers containing chains of Pb(Xterpy)[Au(CN)(2)](+) linked via Au(CN)(2)(-) units. Pb(Brterpy)(mu-OH(2))(0.5)[Au(CN)(2)](2) also contains a bridging water unit. In the plane of the primary crystal growth direction, the birefringence values of the four coordination polymers were found to be 0.378(19), 0.50(3), 0.38(2), and 0.26(3), respectively. The birefringence values are related to the supramolecular structures in terms of maximizing the alignment of the terpyridine-based units and the maximum off-axis positioning of the C-X bonds. With the exception of that for the Pb(Brterpy)(mu-OH(2))(0.5)[Au(CN)(2)](2) polymer, the birefringence values are either as large as or significantly larger than in the related M(2,2';6',2''-terpyridine)[Au(CN)(2)](2) systems. These polymers illustrate the utility of adding polarizable carbon-halogen bonds as a design element in highly birefringent coordination polymers.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".