Crystallographic Investigation of Substituted Allyl and Titanacyclobutane Complexes of Bis(2-<i>N</i>,<i>N</i>-dialkylaminoindenyl)titanium. Structure and Reactivity as a Function of the Dialkylamino Substituents
Bibliographic record
Abstract
Substituted allyl complexes of bis(2- N, N -dialkylaminoindenyl)titanium(III) undergo highly regioselective central carbon alkylation upon treatment with organic free radicals, providing a general synthesis of 2,3-disubstituted titanacyclobutane complexes. This reactivity contrasts that of the corresponding bis(pentamethylcyclopentadienyl)titanium(III) series, for which titanacyclobutane formation is observed only in reactions of the unsubstituted allyl complex. Unexpectedly, the radical alkylation is more general for complexes of bis(2- N, N -dimethylaminoindenyl)titanium than complexes of the closely analogous bis(2-piperidinoindenyl)titanium, despite only subtle differences between the two ancillary ligands. In addition, the 2-methyl-3-alkyltitanacyclobutane complexes derived from alkylation of bis(2- N, N -dimethylaminoindenyl)titanium(η 3 -crotyl) are more thermally robust than those derived from the 2-piperidinoindenyl ligand system, resisting decomposition via β-hydride elimination from the α-methyl substituent. To gain insight into the function of the dialkylaminoindenyl ligands and to probe the differences between 2- N, N -dimethylaminoindenyl and 2-piperidinoindenyl complexes, crystal structures of bis(2- N, N -dimethylaminoindenyl)titanium(η 3 -1-phenylallyl) ( 4a ) and bis(2- N, N -dimethylaminoindenyl)titanium(η 3 -crotyl) ( 4b ) have been determined and compared to the crystal structure of bis(2-piperidinoindenyl)titanium(η 3 -1-phenylallyl), 3a . The effects of allyl coordination on the disposition of the dialkylaminoindenyl ligands are revealed by a comparison with the crystal structure of the corresponding chloride complex, bis(2- N, N -dimethylaminoindenyl)titanium(III)chloride·lithium chloride·(THF) 2, a rare Ti(III)halide/lithium halide adduct. Although it is difficult to control for the effects of crystal packing forces, substantial changes in ancillary ligand structure and orientation are observed as a function of the amino substituent and the coordination environment. The difference in titanacyclobutane stability and the response of the dialkylaminoindenyl ligands to the change in oxidation state have been investigated by comparing the crystal structures of two disubstituted titanacyclobutane complexes, 3-isopropyl-2-phenylbis(2-piperidinoindenyl)titanacyclobutane ( 7 ) and 3-isopropyl-2-phenylbis(2- N, N -dimethylaminoindenyl)titanacyclobutane ( 8 ), each prepared by free radical alkylation.
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 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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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 teacher head, 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".