CH–NH Tautomerism in the Products of the Reactions of the Methanide [HC(PPh<sub>2</sub>NSiMe<sub>3</sub>)<sub>2</sub>]<sup>−</sup> with Pnictogen and Tellurium Iodides
Bibliographic record
Abstract
The reactions of K[HC(PPh 2 NSiMe 3 ) 2 ] (K[ 1 ]) and MI 3 (M = As, Sb) or TeI 4 gave as the major products the complexes [{MI n }{C(PPh 2 NSiMe 3 )(PPh 2 NHSiMe 3 )}] (MI n = trans -AsI 2, trans- or cis -SbI 2, TeI 3 ), which feature the ligand [C(PPh 2 NSiMe 3 )(PPh 2 NHSiMe 3 )] − ( 2 ). This anion, the NH tautomer of [HC(PPh 2 NSiMe 3 ) 2 ] −, is formally generated by a 1,3-hydrogen shift to give complexes in which the ligand is N,C-chelated to the main-group-metalloid center. The M–C distances are slightly longer than the sum of the covalent radii for M and C in the case of the group 15 metalloids but significantly shorter for M = Te. The arsenic derivative [{ t -AsI 2 } 2 ] is monomeric in the solid state, with As–I distances that differ by ca. 0.55 Å, whereas the antimony analogues [{ t -SbI 2 } 2 ] and [{ c -SbI 2 } 2 ] are dimeric through bridging iodide ligands and the disparity in Sb–I distances of the SbI 2 units is 0.10 and 0.33 Å, respectively. The tellurium derivative [{TeI 3 } 2 ] is monomeric with a distorted-square-pyramidal geometry at the Te center and Te–I distances in the narrow range 2.9142(4)–3.0337(4) Å. In contrast to the lighter pnictogens, the bismuth complex [{ t -BiI 2 } 1 ] is comprised of the methanide 1 coordinated in a tridentate (N,C,N) mode to a BiI 2 + cation. In the case of arsenic triiodide, the metathesis is accompanied by Si–N bond cleavage to give [{AsI 2 }{CH 2 (PPh 2 N)(PPh 2 NSiMe 3 )}] ( 3 ), which was characterized by 31 P NMR spectroscopy, and conversion to the corresponding salt [{AsI}{CH 2 (PPh 2 N)(PPh 2 NSiMe 3 )}][SbF 6 ] ( 3A ) by treatment with AgSbF 6 . The As–N distances in the six-membered CP 2 N 2 As ring in 3A differ by 0.20 Å due to the different coordination numbers (2 and 3) of the two N atoms in the novel N,N′-chelated [CH 2 (PPh 2 N)(PPh 2 NSiMe 3 )] − anion. In contrast, reaction of [{ t -SbI 2 } 2 ] with AgSbF 6 gives the expected salt as the dimer {[{SbI} 2 ][SbF 6 ]} 2 . The two hydrolysis products [CH 2 (PPh 2 NSiMe 3 )(PPh 2 NHSiMe 3 )][SbF 6 ] ( 4A ) and [CH 2 (PPh 2 NSiMe 3 ) (PPh 2 NHSiMe 3 )] 2 [Te 2 I 6 ] ( 4B ) were also structurally characterized and shown to contain the same cation. DFT calculations indicate that the N–H tautomer 2 is stabilized by strong M–N and M–C bonding interactions which include a small degree of π character. Weaker bonds, as in the Bi complex, favor the C–H tautomer 1 as the ligand.
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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 | 0.000 | 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".