Side‐On Bridging Coordination of N<sub>2</sub>: Spectroscopic Characterization of the Planar Zr<sub>2</sub>N<sub>2</sub> Core and Theoretical Investigation of Its Butterfly Distortion
Bibliographic record
Abstract
The vibrational and electronic structure of the side-on N(2)-bridged Zr complex [((P(2)N(2))Zr)(2)(mu-eta(2):eta(2)-N(2))] (P(2)N(2)=PhP(CH(2)SiMe(2)NSiMe(2)CH(2))(2)PPh) were analyzed. The vibrational characterization of the planar Zr(2)N(2) core was based on resonance Raman and infrared spectroscopy. In the Raman spectrum, the Nbond;N stretching band is found at 775 cm(-1) with an isotope shift of 22 cm(-1). Due to its appearance in many overtones and combination modes, the metal-metal stretch is assigned to the peak at 295 cm(-1). The two ungerade modes of the Zr(2)N(2) core were identified in the infrared spectrum. Based on these four vibrations of the Zr(2)N(2) unit, a quantum chemical assisted normal coordinate analysis (QCA-NCA) was performed. The force constants for the N--N and Zr--N bonds were calculated to be 1.53 and 2.58 mdyn A(-1), respectively. The butterfly distortion of the Zr(2)N(2) unit obtained in DFT geometry optimizations of planar side-on N(2)-bridged Zr complexes was analyzed in more detail. It was found that on bending of the Zr(2)N(2) core, the lone pairs of the axial amide ligands are rotated by 90 degrees. The bent Zr(2)N(2) unit is 11 kcal mol(-1) lower in energy than the planar core due to a more uniform distribution of electron density between the metal atoms and N(2) and delocalization of electron density from the amide ligands to the Zr(2)N(2) unit. The spectroscopic implications of this distortion are analyzed.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".