Intermolecular Proton−Hydride Bonding in Ion Pairs: Synthesis and Structural Properties of [K(Q)][MH<sub>5</sub>(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>] (M = Os, Ru; Q = 18-crown-6, 1-aza-18-crown-6, 1,10-diaza-18-crown-6)
Bibliographic record
Abstract
The salts [K(Q)][MH 5 (P i Pr 3 ) 2 ] ( 1Os, 1Ru, Q = 18-crown-6; 2Os, 2Ru, Q = 1-aza-18-crown-6; 3Os, 3Ru, Q = 1,10-diaza-18-crown-6) were prepared by the reaction of OsH 2 Cl 2 (PiPr 3 ) 2 or RuCl 3 /2.5PiPr 3 with KH in the presence of one of these crown ethers under an atmosphere of H 2 and were characterized by NMR and infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The X-ray structures of 3Os and 3Ru indicate that short intermolecular proton−hydride interactions between the hydrides of the anion and the NH moieties of the cation cause the self-assembly of one-dimensional networks of pentagonal bipyramidal [MH 5 (P i Pr 3 ) 2 ] - anions and [K(diaza-18-crown-6)] + cations. The X-ray structures of 2Os and 2Ru indicate that these also form one-dimensional chains due to MH···HN and weak MH···HC interactions between the hydrides of the anions and the NH and methylene CH of the [K(aza-18-crown-6)] + cation. The MH···HN distance is 1.7 Å for both 2Os and 2Ru and 1.9 and 1.8 Å for 3Os and 3Ru, respectively. These distances were calculated by assigning a value of 1.0 Å to the N−H bond length and using the refined average Os−H and Ru−H distances of 1.56(4) and 1.58(3) Å observed in 1Os and 1Ru . Values of 2.2 and 2.1 Å were similarly obtained for the MH···HC distances in 2Os and 2Ru, respectively, using a value of 1.09 Å for the C−H bond length. The solid-state infrared spectra of 2Os, 3Os, 2Ru, and 3Ru show shifts in the NH, OsH, and RuH bands to lower frequencies relative to the free NH bands in [K(1-aza-18-crown-6)][BPh 4 ] and [K(1,10-diaza-18-crown-6)][BPh 4 ] and unperturbed OsH and RuH bands in 1Os and 1Ru . Solution NMR and infrared spectra and T 1, NOE, and NOESY experiments demonstrate that the MH···HN interactions persist in solutions of these complexes. The THF solutions of the salts containing proton−hydride bonds undergo efficient H/D exchange with D 2 gas, resulting in deuteration of the hydrides of the [MH 5 (P i Pr 3 ) 2 ] - anion and the NH hydrogens of the [K(1,10-diaza-18-crown-6)] + cation. On the other hand, complexes 1Os and 1Ru that do not have MH···HN bonding do not undergo H/D exchange with D 2 gas. The relative strength of the proton−hydride bonds in the osmium and ruthenium complexes, as evidenced by their NMR and infrared spectral characteristics, is related to the magnitude of the acid dissociation constants of the respective conjugate acids of the anions.
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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 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".