The Use of Polarizable [AuX<sub>2</sub>(CN)<sub>2</sub>]<sup>−</sup> (X = Br, I) Building Blocks Toward the Formation of Birefringent Coordination Polymers
Bibliographic record
Abstract
The [(n)Bu(4)N][AuX(2)(CN)(2)] (X = Br, I) salts were synthesized and structurally characterized. Both feature square-planar [AuX(2)(CN)(2)](-) anions, with trans cyano and halo ligands, which aggregate via halogen-halogen interactions. The aggregation of [AuX(2)(CN)(2)](-) units results in the parallel alignment of all of the Br-Au-Br moieties in the anions along the [110] and [110] directions. Two crystal habits of [(n)Bu(4)N][AuBr(2)(CN)(2)] were grown: with (110) and (001) as the primary faces. The birefringence in the (110) plane was found to be Δn = 0.051(4) and was <0.03 in the (001) plane. Using the [AuBr(2)(CN)(2)](-) unit, [M(phen)(2)][AuBr(2)(CN)(2)](2) (M = Fe, Ni), [Ni(terpy)(2)][AuBr(2)(CN)(2)](2), [Fe(terpy)(2)][AuBr(2)(CN)(2)][ClO(4)], and [Cu(phen)(2)(NO(3))][AuBr(2)(CN)(2)] (phen = 1,10-phenanthroline, terpy = 2,2';6',2''-terpyridine) were synthesized and structurally characterized: they formed ionic structures with coordinatively saturated metal cations and structurally aligning Br···Br interactions between the [AuBr(2)(CN)(2)](-) anions. A molecular complex, Cu(terpy)[AuBr(2)(CN)(2)](2), was prepared, as well as the coordination polymer, [Ni(en)(2)(AuBr(2)(CN)(2))][AuBr(2)(CN)(2)]·MeOH (en = ethylenediamine). The structure consists of layers of chains of Ni(en)(2)(AuBr(2)(CN)(2))(+) units and chains of unbound [AuBr(2)(CN)(2)](-) units formed via Br···Br interactions; a Δn = 0.131(3) was measured. The Δn values were related to the supramolecular structures in terms of the relative intermolecular alignment of Br-Au-Br and NC-Au-CN bonds. These measurements both demonstrate the utility of the Au-Br bonds in enhancing birefringence and show that the contribution of the M-CN units to the overall birefringence of cyanometallate coordinations polymers is non-negligible.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".