Synthesis and Reactivity of [2]Ferrocenophanes with C−Ge and C−Sn Bridges
Bibliographic record
Abstract
The synthesis, characterization, and reactivity of novel carbogerma[2]ferrocenophanes, (η-C 5 Me 4 )Fe(η-C 5 H 4 )CH 2 GeR 2, 11 ( a, R = Ph; b, R = Me), and carbostanna[2]ferrocenophanes, (η-C 5 Me 4 )Fe(η-C 5 H 4 )CH 2 SnR 2, 12 ( a, R = t Bu; b, R = Mes; c, R = Me), are reported. Compounds 11a, b and 12a − c were isolated as orange crystals from the reaction of (η-C 5 Me 4 )Fe(η-C 5 H 4 Li)CH 2 Li· x TMEDA with Cl 2 ER 2 (E = Ge, R = Ph, Me or E = Sn, R = t Bu, Mes, Me) and were characterized by 1 H, 13 C, and 119 Sn NMR, UV/vis, MS, and in representative cases elemental analysis. X-ray diffraction analysis of these species revealed structures possessing moderate ring-tilt with values in the range α = 10.99(2)−11.81(5)° for 11a, b and α = 6.64(2)−7.5(1)° for 12a − c . The presence of a small or moderate degree of ring-strain was further substantiated through the observation of only a small (ca. 25−30 nm) bathochromic shift in the UV/vis absorption maxima when compared to pentamethylferrocene. Attempts to induce thermal ring-opening polymerization (ROP) of 11b and 12a − c proved to be unsuccessful and led only to decomposition at temperatures above 300 °C. Treatment of 11b and 12a − c with amines such as pyridine and 4-(dimethylamino)pyridine did not result in ROP of these compounds. In addition, treatment of 11b and 12a − c with Pt(cod) 2, Pt(PEt 3 ) 3, PtCl 2, Karstedt's catalyst (a Pt(0)-divinyltetramethyldisiloxane complex), PtCl 2 (COD), and n BuLi for 11b and 12c and 2,2‘-azobisisobutyronitrile (AIBN) in the presence of Bu 3 SnH for 12a, b failed to induce any of the insertion or ring-opening reactions that are known for the more highly strained [1]ferrocenophane analogues. However, reactions of 11b and 12a with strong acids such as HCl and 12a with triflic acid (CF 3 SO 3 H) resulted in the formation of the corresponding ring-opened species, (η-C 5 H 5 )Fe(η-C 5 Me 4 CH 2 GeMe 2 Cl), 14, (η-C 5 H 5 )Fe(η-C 5 Me 4 CH 2 Sn( t Bu) 2 Cl), 15, and (η-C 5 H 5 )Fe(η-C 5 Me 4 CH 2 Sn( t Bu) 2 OSO 2 CF 3 ), 16, via selective ipso-Cp−Ge or ipso-Cp−Sn bond cleavage. Treatment of 12b with HCl resulted in selective Sn−Mes bond cleavage, affording (η-C 5 H 4 )Fe(η-C 5 Me 4 )CH 2 SnMesCl, 17 .
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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".