1,4-Phosphagermines: An Anionic 6π-heteroaromatic Biradicaloid and a Persistent π-Delocalized Radical
Bibliographic record
Abstract
Dihetarenes with identical third-period or heavier elements are well established, whereas mixed-element analogues are not. Here, we report the synthesis and characterization of a 1,4-phosphagermine anion and its persistent delocalized radical. The unique synthetic protocol presented herein should be adaptable to other combinations of mixed-heavy main-group elements. Computational analyses (2D-XY NICS π,zz SOM scans and ELF π ) identify it as an aromatic P,Ge-heterocycle, which nonetheless possesses significant biradicaloid character as revealed by PW6B95-D3BJ/def2-QZVP(CPCM THF )//TPSS-D3BJ/def2-TZVP(CPCM THF ) and CASSCF (CASSCF(X,Y)/NEVPT2/def2-TZVP) calculations. Electrochemical studies demonstrate the stability of the radical species, while mild chemical oxidation of the aromatic anion produces the radical, which was identified in solution by EPR spectroscopy. These findings expand the frontier of main-group chemistry, highlighting the potential of mixed-heavy-element aromatic systems. A detailed, comprehensive theoretical study (PW6B95-D3BJ/def2-TZVP(CPCM THF ) level of theory) on 16 combinations of heavy group 14/15 elements reveals an increasing tendency for a biradicaloid character but not the alternative Dewar structure.
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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) | 0.000 | 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) | 0.002 | 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".