Synthesis and Structure of the Hafnium Alkylidene Complex [P<sub>2</sub>Cp]HfCHPh(Cl) ([P<sub>2</sub>Cp] = (η<sup>5</sup>-C<sub>5</sub>H<sub>3</sub>-1,3-(SiMe<sub>2</sub>CH<sub>2</sub>PPr<sup>i</sup><sub>2</sub>)<sub>2</sub>))
Bibliographic record
Abstract
The synthesis, structural characterization, and solution behavior of hafnium complexes stabilized by the potentially tridentate ancillary ligand [P 2 Cp] ([P 2 Cp] = (η 5 -C 5 H 3 -1,3-(SiMe 2 CH 2 PPr i 2 ) 2 )) are described. The reaction of [P 2 Cp]Li with HfCl 4 (THT) 2 produces the hafnium trichloride complex [P 2 Cp]HfCl 3 ( 1 ), the structure of which was determined by X-ray crystallography. Trichloride 1 is isostructural with the analogous zirconium complex [P 2 Cp]ZrCl 3 ( 2 ) in the solid state, but in solution 1 exists as an equilibrium mixture of two isomers that interconvert by fluxional phosphine coordination. Treatment of 1 with 2 equiv of KCH 2 Ph, followed by thermolysis, yields the first structurally characterized hafnium alkylidene complex, [P 2 Cp]Hf CHPh(Cl) ( 3 ). A crystal structure determination obtained for 3 shows this complex to be isostructural with the zirconium analogue [P 2 Cp]Zr CHR(Cl) ( 4 ). The primary difference between the Hf systems presented here and the previously studied Zr analogues is that metal−ligand bonding is stronger in the former, which accounts for shorter bond distances, a greater degree of chemically inertness, and the divergent solution behaviors observed for the trichloride derivatives 1 and 2 .
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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 | 0.001 | 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".