Mono- and Dianionic Guanidinate Ligands. Reactivity of [<sup>i</sup>PrNC(N<sup>i</sup>Pr)<sub>2</sub>]Ta(NMe<sub>2</sub>)<sub>3</sub> and [(<sup>i</sup>PrNH)C(N<sup>i</sup>Pr)<sub>2</sub>]TaCl(NMe<sub>2</sub>)<sub>3</sub> with Me<sub>3</sub>SiCl and ArNC (Ar = 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)
Bibliographic record
Abstract
Reactivities of the dianionic guanidinate complex of [ i PrN C(N i Pr) 2 ]Ta(NMe 2 ) 3 ( 1 ) and the monoanionic guanidinate complex Ta(NMe 2 ) 3 Cl[( i PrN) 2 CN(H) i Pr] ( 4 ) have been investigated. Reaction of 1 with Me 3 SiCl produced compound 2, Ta(NMe 2 ) 3 Cl[( i PrN) 2 CN(SiMe 3 ) i Pr], which is proposed to arise from the addition of the Si−Cl bond across a Ta−N(guanidinate) bond of the starting material rather than one of the Ta−NMe 2 bonds. Complex 2 is the analogue of 4 in which H has been replaced by SiMe 3 . Derivatization of 2 was achieved by reaction with PhCH 2 MgCl to produce Ta(NMe 2 ) 3 (CH 2 Ph)[( i PrN) 2 CN(SiMe 3 ) i Pr] ( 3 ). The single-crystal X-ray-determined structural features of 3 are reported and support the spectroscopic characterization of 3, and indirectly that of 2, by revealing a bidentate tetrasubstituted guanidinate monoanion and an η 1 -benzyl group. Complexes 1 and 4 insert 2,6-dimethylphenyl isocyanide (ArNC) to yield the structurally characterized complex Ta(NMe 2 )[C(N i Pr) 3 ][η 2 -(Me 2 N)C N(2,6-Me 2 C 6 H 3 )] 2 ( 5 ), which possesses one dianionic bidentate guanidinate ligand and two η 2 -iminocarbamoyl ligands derived from the insertion of ArNC into two of the Ta−NMe 2 bonds of the starting materials. The formally seven-coordinate Ta(V) center of 5 can be viewed as pseudo trigonal bipyramidal, with each of the η 2 -C N linkages occupying a single coordination site. In the case of 4, the transformation of the guanidinate anion into its dianionic form was concomitant with insertion of ArNC. The sources of base for the deprotonation of the guanidinate ligand are likely the amido groups of a portion of the starting material.
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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 | 0.012 | 0.006 |
| Meta-epidemiology (narrow) | 0.022 | 0.024 |
| Meta-epidemiology (broad) | 0.023 | 0.010 |
| Bibliometrics | 0.010 | 0.021 |
| Science and technology studies | 0.009 | 0.011 |
| Scholarly communication | 0.008 | 0.013 |
| Open science | 0.012 | 0.010 |
| Research integrity | 0.012 | 0.017 |
| Insufficient payload (model declined to judge) | 0.001 | 0.005 |
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".