2-Indolylphosphines, a New Class of Tunable Ligands: Their Synthesis, Facile Derivatization, and Coordination to Palladium(II)
Bibliographic record
Abstract
The generation of new metal complexes with potentially interesting properties provides the motivation for designing novel polydentate bridging ligands. Herein we report the syntheses of tertiary indolylphenylphosphines L, where L = diphenyl(3-methyl-2-indolyl)phosphine (P(C 6 H 5 ) 2 (C 9 H 8 N), 1 ), phenylbis(3-methyl-2-indolyl)phosphine (P(C 6 H 5 )(C 9 H 8 N) 2, 2 ), and bis(1 H -3-indolyl)methane-(2,12)-phenylphosphine (P(C 6 H 5 )(C 17 H 12 N 2 ), 3 ). Ligands 1 − 3 were functionalized at the indolyl nitrogen with a variety of both electron-withdrawing and electron-donating groups. The solid-state structures of 1, 2, and N-functionalized indolylphosphines diphenyl(3-methyl-1-benzyl-2-indolyl)phosphine (P(C 6 H 5 ) 2 (C 9 H 7 N(CH 2 C 6 H 5 )), N -Bz-1 ) and bis[1-(CH 2 C 6 F 5 )-3-indolyl]methane-(2,12)-phenylphosphine (P(C 6 H 5 )(C 17 H 10 N 2 [CH 2 C 6 F 5 ] 2 ), ( N -F 5 Bz) 2 -3 ), are reported. The reaction of ligands 1 − 3 with 1 equiv of Pd(COD)Cl 2 led to the formation of Pd(II) complexes of the type [Pd( L )Cl(μ-Cl)] 2 ( 4, L = 1; 5, L = 2; 6, L = 3 ). The products were characterized by 1 H, 13 C, and 31 P NMR spectroscopy, mass spectrometry, and elemental analysis. X-ray crystallography established the dimeric structure of the products and confirmed the ability of the ligands to serve, in the absence of base, as monodentate P-donors in reaction with a transition metal. The indolyl NH groups of the complexes 4 − 6 demonstrate a marked propensity for hydrogen bonding in the solid state.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".