Synthesis and Structural Characterization of η<sup>6</sup>-Arene Ruthenium Complexes Bearing Pentadienyl and Oxopentadienyl Ligands
Bibliographic record
Abstract
General methodology for the synthesis of cationic ruthenium(II) η 5 -pentadienyl compounds stabilized by the (η 6 -C 6 Me 6 )Ru fragment has been developed. Pentadienyl compounds [(η 6 -C 6 Me 6 )Ru{η 5 -CH 2 C(R 2 )CHC(R 4 )CH(R 5 )}]BF 4 (R 2 = R 4 = R 5 = H, 2 -BF 4; R 2, R 4 = H, R 5 = Me, 3; R 2, R 4 = Me, R 5 = H, 4 ) can be prepared in good yields from reactions of the labile dication [(η 6 -C 6 Me 6 )Ru(acetone) 3 ](BF 4 ) 2 ( 1 ) with 1-trimethylsilyl-2,4-pentadiene, 1-trimethylsilyl-2,4-hexadiene, and 2,4-dimethyl-1-trimethylstannyl-2,4-pentadiene, respectively. Compound 3 is isolated in 90% yield as a mixture of the syn and anti isomers. In contrast, the reaction of pentadienyllithium with [(η 6 -C 6 Me 6 )RuCl 2 ] 2 provides a nonselective reaction, which affords a mixture of isomeric η 1 -, η 3 -, and η 5 -coordinated pentadienyl complexes, [(η 6 -C 6 Me 6 )Ru(η 5 -CH 2 CHCHCHCH 2 )]Cl ( 2 -Cl), [(η 6 -C 6 Me 6 )Ru(η 3 -CH 2 CHCHCH CH 2 )Cl] ( 5 ), and [(η 6 -C 6 Me 6 )Ru(η 1 -CH 2 CH CHCH CH 2 )Cl] 2 ( 6 ); the reaction of 1,4-pentadiene and [(η 6 -C 6 Me 6 )RuCl 2 ] 2 in ethanolic carbonate similarly gives a mixture containing complex 5, [(η 6 -C 6 Me 6 )Ru{η 3 -C(Me)CHC(Me)}Cl] ( 7 ), and [(η 6 -C 6 Me 6 )Ru(η 3 -CH 2 CHCHCH 2 Me)Cl] ( 8 ). Using a similar strategy for the synthesis of the corresponding oxopentadienyl derivatives is much more complicated, even when using an enol silane as the nucleophilic precursor, reflecting a greater competition among alternative bonding modes for the oxopentadienyl derivatives compared to the corresponding pentadienyl analogues. The reaction of lithium oxopentadienide and [(η 6 -C 6 Me 6 )RuCl 2 ] 2 in THF affords [(η 6 -C 6 Me 6 )Ru(η 3 - exo - syn -CH 2 C(Me)CHC(Me)O)Cl] ( 11 ) in poor yield, although this complex readily affords [(η 6 -C 6 Me 6 )Ru(η 5 -CH 2 C(Me)CHC(Me)O)]BF 4 ( 9 ) upon reaction with silver tetrafluoroborate. The analogous η 6 -benzene complex, [(η 6 -C 6 H 6 )Ru(η 3 - exo - syn -CH 2 C(Me)CHC(Me)O)Cl] ( 13 ), can be prepared, albeit in very low yield, in an analogous manner to that reported for complex 11, along with traces of an isomeric congener, 13 - endo . The use of 1-trimethylsilyloxy-1,3-butadiene unexpectedly provided strongly contrasting results upon addition to dicationic complex 1, returning a mixture of η 5 - and η 3 -oxopentadienyl complexes [(η 6 -C 6 Me 6 )Ru(η 5 -CH 2 CHCHCHO)]BF 4 ( 14 ) and [(η 6 -C 6 Me 6 )Ru(1−3,5-η- exo-syn -CH 2 CHCHCHO)] 2 (BF 4 ) 2 ( 15 ). Addition of water to the dimeric product 15 affords the monomeric aquo adduct [(η 6 -C 6 Me 6 )Ru(η 3 - exo-syn- CH 2 CHCHCHO)(H 2 O)]BF 4 ( 16 ), but this complex is unstable toward isolation, reverting back to dimer 15 upon precipitation. A more stable adduct, [(η 6 -C 6 Me 6 )Ru(η 3 - exo - syn- CH 2 CHCHCHO)(MeCN)]BF 4 ( 17 ), is isolated upon dissolution in acetonitrile, and addition of aqueous NaCl to 15 gives compound [(η 6 -C 6 Me 6 )Ru(η 3 - exo - syn- CH 2 CHCHCHO)Cl] ( 20 ). Compound 14 affords the decarbonylation product [(η 6 -C 6 Me 6 )Ru(η 3 -allyl)(CO)]BF 4 ( 19 ) as a mixture of exo and endo allyl isomers. The solid-state structures for compounds 2 -BF 4, 4, 9, 11, 13, 15, and 19- exo, as determined by X-ray crystallography, are also reported.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.006 | 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".