Organotitanium Complexes Supported by a Dianionic Pentadentate Ligand
Bibliographic record
Abstract
The pentadentate tetrapyrazolylpyridyl diborate ligand B 2 Pz 4 Py has been complexed to Ti III to form the chloro complex (B 2 Pz 4 Py)Ti III Cl, which is a convenient starting material for preparing alkyl and hydride derivatives of this ligand. The former (R = CH 3 and CH 2 SiMe 3 ) are highly thermally stable and do not react with dihydrogen to form (B 2 Pz 4 Py)Ti III H. Rather, treatment of the chloro starting material with NaHBEt 3 affords the desired hydrido complex in 85% yield. This Ti III hydride was fully characterized and exists in both solution and the solid state as a dimeric species; dissociation into monomers faces a high barrier of over 60 kcal/mol, according to density functional theory computations. This is due to stabilization of the dimer by dispersion forces. The computations show that the dimer has an open-shell singlet ( S = 1) ground state, which is consistent with the magnetic susceptibility of 1.73 μ B per titanium center measured by the Evans method. However, the triplet state is very close in energy. The large barrier to dissociation into reactive monomers is reflected in the observed lack of reactivity with carbon dioxide to form the expected formato derivative, which can be prepared separately from (B 2 Pz 4 Py)Ti III Cl and sodium formate. Both the hydrido and alkyl Ti III compounds react with water to form a μ-oxo dinuclear species, which reacts further with dioxygen to form oxidized peroxo and oxo Ti IV complexes. All three of these compounds were fully characterized.
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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) | 0.002 | 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".