Synthesis, characterization, and crystal structures of novel oligomeric Zn(II) and Cd(II) complexes with <i>N</i>,<i>N</i>′-dimethyl-2,2′-biimidazole
Bibliographic record
Abstract
Zn(II) and Cd(II) complexes with N,N′-dimethyl-2,2′-biimidazole (Me2biim) were synthesized and characterized by IR spectroscopy and by X-ray crystallographic methods. The reaction of zinc perchlorate with Me2biim produced the dinuclear compound [(Me2biim)Zn(µ-Me2biim)3Zn(Me2biim)](ClO4)4, containing two monodentate and three bridging Me2biim ligands bonded to Zn atoms in a distorted tetrahedral environment. A related neutral (NO3)2Cd(µ-Me2biim)3Cd(NO3)2 complex, containing only bridging Me2biim ligands, was also synthesized, in which the distorted octahedral coordination of each Cd atom is completed by one monodentate and one bidentate nitrato ligand. Two ionic trinuclear Cd compounds were also obtained, which include two sets of three bridging Me2biim ligands connecting a central Cd atom to two terminal Cd centers. An extra Me2biim ligand is chelated to each terminal metal, and the sixth coordination site is occupied by water molecules in the symmetric [(Me2biim)(H2O)Cd(µ-Me2biim)3Cd(µ-Me2biim)3Cd(H2O)(Me2biim)](ClO4)6 complex, whereas the aqua ligand is replaced by methanol at one of the terminal units in the non-symmetric [(Me2biim)(H2O)Cd(µ-Me2biim)3Cd(µ-Me2biim)3Cd(CH3OH)(Me2biim)](ClO4)6 compound. In the chelating ligands, dihedral angles of ~38° between the two imidazole rings reduce repulsion between the N-methyl groups, but considerable strain remains, as evidenced from one of the Cd–N bonds being much longer than the other. In the various compounds, dihedral angles of 60–80° are found between the imidazole rings in the bridging ligands, and intramolecular inter-ligand π–π stacking contributes to stabilization.Key words: zinc, cadmium, dimethylbiimidazole, crystal structure, dinuclear, trinuclear.
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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) | 0.001 | 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".