Palladium(II) and Platinum(II) Complexes Featuring a Nitrile-Functionalized N-Heterocyclic Carbene Ligand
Bibliographic record
Abstract
The transmetalation reaction of 2 equiv of trans- PdCl 2 (CH 3 CN) 2 or Pd(cod)Cl 2 with a nitrile-functionalized N-heterocyclic carbene complex of silver(I), bis[1-(2-cyanophenyl)-3-methylimidazol-2-ylidene]silver(I) tetrafluoroborate ([Ag( m -CN) 2 ]BF 4, 1 ), and 1 equiv of AgBF 4 afforded a bimetallic complex formulated as [( m -CN) 2 Pd(μ-Cl) 2 Pd(CH 3 CN) 2 ](BF 4 ) 2 ( 2a ). The interesting trimetallic complex 2b was obtained during an attempt to crystallize 2a from wet diethyl ether and acetonitrile. The solid-state structure of 2b reveals the presence of a novel C−N−N−C donor ligand providing two bridging imido nitrogens to adjacent palladium(II) centers in the trimetallic complex [{Pd(CH 3 CN) 2 } 3 (C−N−N−C)](BF 4 ) 4 ( 2b ). The C−N−N−C ligand, which has a central −N═C−O−C═N− linkage, was formed from the hydrolysis and condensation of the nitrile groups of two carbene ligands. Palladium(II) and platinum(II) complexes bearing chelating olefin and N-heterocyclic carbene ligands were synthesized by transmetalation reactions of N-heterocyclic carbene complexes of silver(I), complex 1 and bis[1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene]silver(I) tetrafluoroborate ([Ag(IMes) 2 ]BF 4, 7 ), with [Pd(η 1:η 2 -coe-OMe)(μ-Cl)] 2 and Pt(cod)Cl 2 (coe-OMe = 2-methoxycyclooct-5-enyl, cod = 1,5-cyclooctadiene) or by addition of a methoxide anion to the coordinated diolefin ligand of the novel platinum(II) complex, chloro[1-(2-cyanophenyl)-3-methylimidazol-2-ylidene](η 4 -1,5-cyclooctadiene)platinum(II) tetrafluoroborate ([Pt( m -CN)(cod)Cl]BF 4, 4 ). The complexes bearing 1-(2-cyanophenyl)-3-methylimidazol-2-ylidene and 2-methoxycyclooct-5-enyl ligands ([M( m -CN)(η 1:η 2 -coe-OMe)] +: 3, M = Pd; 6, M = Pt) exists in both monomeric and dimeric forms depending on the choice of recrystallization solvents. All of these complexes were isolated and studied by NMR and infrared spectroscopy. Different ratios of rotamers were observed for the complexes bearing a 2-methoxycyclooct-5-enyl ligand owing to its orientation relative to the carbene ligand. Rotamers are believed to form because of steric restrictions to rotation about the M−C carbene bond (M = Pd, Pt).
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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 | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".