Isolation and characterization of an unusually stable formamidinium-containing macrotricyclic complex of lithium ion formed during the synthesis of 14-thia-1,4,8,11-tetraaza-bicyclo[9,5,3]nonadecane
Bibliographic record
Abstract
Using 1,3-bis(chloroacetamido)propane (5) as the common intermediate, an efficient route is described to the stepwise syntheses of 1-thia-4,8-diazacyclodecane, [10]aneN 2 S (8), and the pentadentate macrobicycle 17-thia-1,4,8,11-tetraazabicyclo[9,5,3]-nonadecane (11). During the investigation of the condensation of (5) with (8), with Li 2 CO 3 used as a base the Li + cation is carried over as the complex of the dioxo intermediate (10) and survives further reduction. Prolonged contact of these complexes with CHCl 3 during cyclisation and extraction (in the presence of Li 2 CO 3 and NaOH, respectively), leads to the formation of the complex cation [Li(4)] 2+ as a byproduct in which the cationic macrocycle (4), containing a formamidinium ring, is formed through bridging of the 1,11-nitrogens in the macrobicycle (11) by a -CH= group that is derived from CHCl 3 . This renders the cavity in (4) too small for the inclusion of transition metal ions. Reaction of the lithium cation [Li(4)] 2+ with PdCl 2 yielded the trimetallic salt [(Li(4)]-PdCl 2 -[(Li(4)])](ClO 4 ) 4 in which two [Li(4)] 2+ ions are bridged by a PdCl 2 unit through coordination of the pendant thioether donors. A crystal structure of this trimetallic salt confirms the formation of [Li(4)] 2+ . In contrast, if triethylamine is used as a base during the cyclisation reaction leading to the formation of (11) and contact with aqueous NaOH and CHCl 3 during its isolation is minimized, the formation of (4) is prevented and the yield of (11) improved.Key words: macrobicycle synthesis, lithium, formamidinium, paaladium, complex.
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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 | 0.001 | 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) | 0.000 | 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".