Rare Carbon-Bridged Bimetallic Lanthanide (Nd or Sm) and Tl(I) Geminal Carbon Derivatives of a Bis(iminophosphorano)methanediide
Bibliographic record
Abstract
The bimetallic carbon-bridged bis(iminophosphorano)methanediide complexes [CpNd(Tl){C(Ph 2 P═NSiMe 3 ) 2 }Cl 2 Li(THF) 2 ]·Et 2 O ( 2 ) and [SmCl 3 Tl{C(Ph 2 P═NSiMe 3 ) 2 }Li(THF) 2 ] 2 ( 3 ) were prepared from reactions of the dilithiated bis(iminophosphorano)methanediide [Li 2 L] ( 1; L = C 2– (Ph 2 P═NSiMe 3 ) 2 ) with Nd and Sm chlorides and with CpTl and TlCl, respectively, in THF. Both final products contain coordinated Li linked with Cl bridges. The complexes have been structurally characterized and show that the bridging methanediide backbone carbon of the ligand is substituted with one Tl(I) and one rare-earth atom and has a tetrahedral geometry. The 31 P{ 1 H} NMR spectrum (THF- d 8 ) of 2 shows a broad signal at 13.75 ppm with a two-bond spin–spin coupling ( 2 J Tl–P = 410 Hz), indicating that the C–Tl bond is maintained in solution. The 31 P{ 1 H} NMR spectrum of 3 was less informative because the complex is more paramagnetic, and thus only a very broad single peak was observed. DFT calculations on the model compounds [CpNd(Tl){C(PhMeP═NSiH 3 ) 2 }Cl 2 Li(THF) 2 ] ( 2a ) and [SmTl{C(PhMeP═NSiH 3 ) 2 Cl 2 ] 2 ( 3a ), whose crystal structures are based on those for 2 and 3, were performed; the results clearly demonstrate the bonding characteristics among the metal centers (Nd(III), Sm(III), Tl(I)) and bridged carbon. In contrast to most Tl(I) compounds, 2 and 3 are reasonably stable in air; this is attributed to protection of the Tl(I) by some of the phenyl substituents on the phosphorus through π-bonding interactions. X-ray and DFT data indicate that, for 2, Tl(I) is a five-coordinate center through one strong carbene carbon bond and four weak phenyl carbon bonds, while for 3, Tl(I) is six-coordinate through strong carbene carbon and chloride bonds and four weak phenyl carbon bonds. These complexes are the first examples of a single carbon or carbene forming a bridge between the main-group heavy metal Tl(I) and another rare-earth metal.
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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) | 0.001 | 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 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".