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 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 | 0.006 | 0.006 |
| Meta-epidemiology (narrow) | 0.015 | 0.015 |
| Meta-epidemiology (broad) | 0.016 | 0.010 |
| Bibliometrics | 0.006 | 0.017 |
| Science and technology studies | 0.007 | 0.008 |
| Scholarly communication | 0.005 | 0.006 |
| Open science | 0.014 | 0.009 |
| Research integrity | 0.009 | 0.011 |
| Insufficient payload (model declined to judge) | 0.002 | 0.004 |
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; both teacher heads agree on what is shown here.
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".