Synthesis, Structure, and Properties of [(tmeda)Cu[Hg(CN)<sub>2</sub>]<sub>2</sub>][HgCl<sub>4</sub>]: A Non-Centrosymmetric 2-D Layered System that Shows Strong Optical Anisotropy
Bibliographic record
Abstract
The first coordination polymer incorporating Hg(CN) 2 units as building blocks is reported. The reaction of the labile transition-metal halide CuCl 2, the soft Lewis acidic Hg(CN) 2, and N,N,N‘,N‘-tetramethylethylenediamine (tmeda) formed large single crystals of [(tmeda)Cu[Hg(CN) 2 ] 2 ][HgCl 4 ] ( 1 ). The migration of two labile chloride ligands from harder Cu(II) to softer Hg(II) drives the formation of 1, which self-assembles in high yield from several combinations of reagents. Complex 1 crystallizes in the tetragonal, noncentric P 4̄2 1 m space group, Z = 2, with a = b = 10.9576(12) Å and c = 9.8516(13) Å. The structure is composed of a 2-D cationic layer of [(tmeda)Cu[Hg(CN) 2 ] 2 ] 2+ units in which the six-coordinate Cu(II) centers are bridged by four Hg(CN) 2 groups and capped by a tmeda ligand. This array is interspersed with a layer of [HgCl 4 ] 2 - anions, which form bridging Hg−Cl bonds with the Hg(CN) 2 units. At 300 K, a - or b -oriented single-crystal plates of 1 are strongly birefringent with a birefringence value of Δ n = 6.38 × 10 - 2, as measured at λ = 546.1 nm. The strongly anisotropic crystal structure, including the highly polarizable Hg(II) ions, is responsible for this significant optical birefringence. Upon cooling, the birefringence of 1 decreases slightly to Δ n = 6.12 × 10 - 2 at 90 K.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".