The Dewar–Chatt–Duncanson model reversed — Bonding analysis of group-10 complexes [(PMe <sub>3</sub> ) <sub>2</sub> M–EX <sub>3</sub> ] (M = Ni, Pd, Pt; E = B, Al, Ga, In, Tl; X = H, F, Cl, Br, I)
Bibliographic record
Abstract
Quantum chemical calculations using BP86 with TZ2P basis sets were carried out to elucidate the structures and the bond–bond dissociation energies of the donor–acceptor complexes [(PMe 3 ) 2 M–EX 3 ] with X = H, F, Cl, Br, I; E = B, Al, Ga, In, Tl; and M = Ni, Pd, Pt. The nature of the metal–ligand bond was investigated with an energy decomposition analysis. The geometry optimizations gave for most compounds T-shaped structures with nearly linear P–M–P angles where the EX 3 ligand has either a staggered or eclipsed conformation with respect to the PMP plane. The energy differences between the conformations are very small which means that there is nearly free rotation about the M–EX 3 axis. The equilibrium structures of eight nickel compounds have a distorted geometry where one E–X bond is engaged in attractive interactions with the metal atom which yields a distorted square-planar arrangement of the metal atom. The complex [(PMe 3 ) 2 Ni–TlI 3 ] exhibits two attractive interactions between Tl–I bonds and the metal which features a five-coordinated metal atom. The calculated bond dissociation energies show that the boron complexes exhibit a different trend for the D e values than the heavier group-13 homologues. The results for the Pd and Pt complexes suggest that the [(PMe 3 ) 2 M–BX 3 ] bond strength increases with F < Cl < Br < I < H which means that the BH 3 ligands are the most strongly bonded Lewis acids and BF 3 is the most weakly bonded species . The trend for the heavier group-13 complexes [(PMe 3 ) 2 M–EX 3 ] where E = Al, Ga, In, Tl follows the opposite order F > Cl > Br > I > H. The energy decomposition analysis of the M–EX 3 bonds indicates a substantial π contribution of between 12.7% and 30.3% to the total orbital interactions. There is no direct correlation between the strength of the orbital interactions or any of the other energy terms ΔE elstat or ΔE Pauli which correlates with the total interaction energy. The bond dissociation energy of the EX 3 ligands after breaking the M–EX 3 bonds is quite large. It is shown that the intrinsic strength of the M–EX 3 bonds is much larger than the BDEs and that the trends of ΔE int and D e are not always the same. The EX 3 ligands in [(PMe 3 ) 2 M–BX 3 ] always carry a large negative charge.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.014 | 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".