Does Cr(CO)<sub>3</sub> Complexation Reduce the Aromaticity of Benzene?
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Bibliographic record
Abstract
Ring currents in (C 6 H 6 )Cr(CO) 3, 1, ( cis -1,3-butadiene)Cr(CO) 4 ( 4 ), (C 6 H 6 ) 2 Cr ( 5 ), (C 4 H 4 )Fe(CO) 3 ( 6 ), and ( cis -1,3-butadiene)Fe(CO) 3 ( 8 ) have been assessed by σ−π disected nucleus independent chemical shift (NICS) calculations. Shielding contributions from the C−C(π) orbitals to the NICS values reveal that there is no quenching of ring current in the benzene ring of 1 or in dibenzene chromium 5 . The previously reported paratropic ring current for 1 is shown to be a consequence of latent aromaticity in 1,3-butadiene chromium tetracarbonyl 4 (one of the molecules used in the magnetic susceptibility equation). NICS values, a diatropic ring current, and a positive aromatic stabilization energy (ASE) all point to this aromaticity. NICS values for cyclobutadiene iron tricarbonyl, 6, show moderately sized diamagnetic shielding above the plane of the four-membered ring. In addition, 6 has a negative magnetic susceptibility exaltation (MSE) (diatropic ring current), quite opposite from the large paratropic current calculated for cyclobutadiene ( D 2 h ) itself. Evaluated using “strain corrected” isodesmic reactions, 6 has a large ASE in contrast to a large destabilization calculated for cyclobutadiene with the same equation. The 1,3-butadiene complex 8 also shows features of three-dimensional aromaticity, NICS(1) −8.7, NICS(1) π −2.8, and a moderate ASE stabilization energy (7.9 kcal/mol, eq 7), but this complex has a negligible MSE of −1.0 ppm cgs. We predict the ring current order to be the following: benzene ∼ 1 ∼ 5 > 6 > 4 > 8 .
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| 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 | 0.000 | 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 it