Bis-hydrocarbyl Platinum(II) Ambiphilic Ligand Complexes: Alkyl–Aryl Exchange between Platinum and Boron
Bibliographic record
Abstract
Reaction of TXPB (2,7-di- tert -butyl-5-diphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene) with [PtMe 2 (COD)] (COD = 1,5-cyclooctadiene) yielded [PtMePh(TXPB′)] ( 1; TXPB′ = 2,7-di- tert -butyl-5-methylphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene), presumably via undetected [PtMe 2 (TXPB)]. The ambiphilic ligand in 1 is κ 2 PS -coordinated, and the trigonal plane of the borane is oriented approximately parallel to the square plane at platinum. In solution, 1 is in equilibrium with zwitterionic [PtMe(TXPB-Me)] ( 1 ′), in which the Pt -phenyl group in 1 has been abstracted by the borane; the ratio of 1 to 1 ′ is approximately 90:10 at room temperature and 50:50 at 183 K. The presence of 1 ′ in solution suggests that the pathway for phenyl–methyl exchange between platinum and boron involves a zwitterionic platinum(II) intermediate, rather than a platinum(IV) boryl complex resulting from B–C bond oxidative addition. Heating compound 1 provided an approximate 14:86 mixture of 1 and [PtPh 2 (TXPB″)] ( 2; TXPB″ = 2,7-di- tert -butyl-5-dimethylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene); 1 and 2 are in equilibrium at elevated temperature, and 2 is formed (Δ S ⧧ = −45(12) J K –1 mol –1; Δ H ⧧ = 94(4) kJ mol –1 ) via a second methyl–phenyl exchange between platinum and boron. The solid-state structure of 2 is analogous to that of 1, except with both phenyl groups on platinum and both methyl groups on boron. Compound 1 reacted with PPh 3 or P(OPh) 3 to afford neutral [PtMePh(L)(TXPB′)] {L = PPh 3 ( 3 ) or P(OPh) 3 ( 4 )}, in which the TXPB′ ligand is κ 1 P -coordinated. However, 1 reacted with 2 equiv of CNXyl (Xyl = 2,6-dimethylphenyl) to provide zwitterionic trans -[PtMe(CNXyl) 2 (TXPB-Me)] ( 5; TXPB-Me is a κ 1 P -coordinated anionic phosphine). This divergent reactivity is consistent with the accessibility of both neutral 1 and zwitterionic 1 ′ in solution.
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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) | 0.003 | 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".