Potassium and Yttrium Complexes of a Rigid Bis‐Phosphido POP‐Donor Ligand
Bibliographic record
Abstract
Dilithiation of 4,5‐dibromo‐2,7‐di‐tert‐butyl‐9,9‐dimethyl‐xanthene (XBr2) followed by addition of 2 equiv. of (2,4,6‐triisopropylphenyl)dichlorophosphine (TrippPCl2) afforded 4,5‐bis[(2,4,6‐triisopropylphenyl)chlorophosphino]‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene (XP2Cl2), which was reduced to 4,5‐bis[(2,4,6‐triisopropylphenyl)phosphino]‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene (H2XP2) using excess LiAlH4. Deprotonation of H2XP2 with excess KH in DME provided the dipotassium salt, [K2(XP2)(dme)n] (1; n = 2.5–4), and stirring 1 in THF followed by recrystallization from hexanes yielded tetrametallic [K4(XP2)2(THF)4] (2) which features a central K4P4 cage. Reaction of [YI3(THF)3.5] with [K2XP2(dme)2.5] afforded a mixture of products including [(XP2)YI(THF)2] (3) and (PTripp)3; pure 3 could be isolated in low yield by extraction with a minimum volume of hexanes or O(SiMe3)2. In the solid state, 3 adopts a face‐capped trigonal bipyramidal coordination geometry with a planar xanthene backbone and an angle of 85° between the P(1)/C(4)/C(5)/P(2) and P(1)/Y/P(2) planes.
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".