Sulfur K-edge X-ray absorption near-edge spectral analysis of thiourea free ligand and its Zn(II), Co(II), and Ni(II) complexes
Bibliographic record
Abstract
Electronic supporting information for the analysis and interpretation of sulfur K-edge X-ray absorption near-edge spectra of thiourea free ligand and its [Zn(TU)4]2+, [Co(TU)4]2+, and [Ni(TU)6]2+ complexes. Sulfur K-edge X-ray absorption spectroscopy (XAS) was employed to experimentally define the nature of coordinative bond between thiourea (TU) or thiocarbamide ligand and Zn2+, Co2+, and Ni2+ ions in distorted tetrahedral and octahedral homoleptic coordination environments. Comparisons of XAS spectra of the free TU ligand, [Zn(TU)4]2+, [Co(TU)4]2+, and [Ni(TU)6]2+ complexes clearly identify spectral features emerging from the structural non-innocent TM2+–S(TU) bonding. Quantitative analysis of pre-edge intensities describes the covalency of Ni2+– and Co2+–S(TU) bonding to be at most 23% and 9% as expressed by the S 3p contributions per 3d electron hole. Using relevant Ni2+ complexes with dithiocarbamate and thioether ligands, we evaluated the empirical S 1s→3p transition dipole integrals developed for sulfur ligands and its dependence on heteroatom substitutions. With the aid of density functional theory-based ground electronic state calculations, we found evidence for the need of using a transition dipole that is dependent on the presence of conjugated heteroatom (N) substitution in the S-ligands. Table of Contents: Worksheets "transition dipole" and "spectral modeling summary" contain data for empirical S 1s->3p transition dipole integral estimates and summary of spectral modeling, respectively. RAW_DATA folder: ASCII formatted S K-edge XAS data from BL 4-3 of SSRL, and data obtained for the [Ni(TU)6]2+ complex at the double-crystal monochromator beamline (formerly Canadian Beamline) of Synchrotron Research Center (the home of Aladdin), in Stoughton, Wisconsin. SPECTRAL_MODELS folder Electronic spreadsheets, PeakFit spectral fitting templates, spectra as user-defined functions, quantitative analysis of pre-edge feature intensities XRD_STRUCTURES folder Xmol (XYZ) and DSViewerPro (MSV) files for the analysis of the crystal packing environment of TU complexes. DFT_CALCULATIONS Gaussian09 log files for free thiourea, Co(II) and Ni(II) complexes at BP86/def2TZVP, B3LYP/def2TZVP, and TPSS/def2TZVP levels of theory; frequency calculations for IR vibrational spectral simulations.
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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 | 0.001 | 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 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".