Syntheses and Structures of TcOF<sub>5</sub>and the Tc<sub>2</sub>O<sub>2</sub>F<sub>9</sub><sup>+</sup>Cation and Formation of the TcOF<sub>4</sub><sup>+</sup>Cation in Solution
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Bibliographic record
Abstract
The last member of the series of technetium(VII) oxide fluorides, TcOF 5, has been prepared by oxidative fluorination of TcO 2 F 3 with KrF 2 in anhydrous HF. The pseudooctahedral ( C 4 v ) structure of TcOF 5 has been determined by 19 F and 99 Tc NMR, Raman, and infrared spectroscopies and by single-crystal X-ray diffraction. TcOF 5 crystallizes in the orthorhombic crystal system, space group Pna 2 1, with a = 9.235(3) Å, b = 4.939(2) Å, c = 8.502(3) Å, V = 387.7(2) Å 3, and Z = 4 at −102 °C, R 1 = 0.0256 and wR 2 = 0.0730. TcOF 5 behaves as a fluoride ion donor toward AsF 5 and SbF 5 in HF solvent, giving the Tc 2 O 2 F 9 + cation, which has been characterized as the AsF 6 - and Sb 2 F 11 - salts by Raman spectroscopy and as the [Tc 2 O 2 F 9 ][Sb 2 F 11 ] salt by single-crystal X-ray diffraction. [Tc 2 O 2 F 9 ][Sb 2 F 11 ] crystallizes in the orthorhombic crystal system, space group Pbcm, with a = 6.2925(4) Å, b = 21.205(2) Å, c = 11.7040(8) Å, V = 1561.7(2) Å 3, and Z = 8 at −90 °C, R 1 = 0.0368 and wR 2 = 0.0896. The Tc 2 O 2 F 9 + cation consists of two fluorine-bridged square pyramidal TcOF 4 groups in which the fluorine bridge is trans to the oxygens. Solution 19 F and 99 Tc NMR spectra of Tc 2 O 2 F 9 + salts in HF and of TcOF 5 dissolved in SbF 5 are consistent with the formation of the TcOF 4 + cation. Local density functional theory has been used to calculate the geometrical parameters, vibrational frequencies, and 19 F and 99 Tc NMR parameters of MOF 5 (M = Tc, Re, Os) and Tc 2 O 2 F 9 +, which are in good agreement with available experimental values. The results of ab initio calculations and normal coordinate analyses for MOF 5 confirm the trans influence of oxygen, which leads to lengthening of the axial fluorine−metal bond length and a correspondingly lower stretching force constant relative to that of the shorter equatorial metal−fluorine bonds.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it