Syntheses, Crystal Structures, and Density Functional Theory Calculations of the <i>c</i><i>loso</i>-[1-M(CO)<sub>3</sub>(η<sup>4</sup>-E<sub>9</sub>)]<sup>4</sup><sup>-</sup> (E = Sn, Pb; M = Mo, W) Cluster Anions and Solution NMR Spectroscopic Characterization of [1-M(CO)<sub>3</sub>(η<sup>4</sup>-Sn<sub>9</sub>)]<sup>4</sup><sup>-</sup> (M = Cr, Mo, W)
Bibliographic record
Abstract
The closo-[1-M(CO)(3)(eta(4)-E(9))](4-) (E = Sn, Pb; M = Mo, W) anions have been obtained by extracting the binary alloys KSn(2.05) and KPb(2.26) in ethylenediamine (en) in the presence of 2,2,2-crypt or in liquid NH(3) followed by reaction with M(CO)(3).mes (M = Mo, W) or Cr(CO)(3).tol in en or liquid NH(3) solution. Crystallization of the molybdenum and tungsten salts was induced by vapor diffusion of tetrahydrofuran into the en solutions. The salts [2,2,2-crypt-K](4)[1-M(CO)(3)(eta(4)-Sn(9))].en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 4, a = 16.187(3) A, b = 25.832(4) A, c = 29.855(5) A, alpha = 111.46(1) degrees, beta = 102.84(2) degrees, gamma = 92.87(2) degrees at -95 degrees C (M = Mo) and a = 17.018(3) A, b = 27.057(5) A, c = 28.298(6) A, alpha = 66.42(3) degrees, beta = 76.72(3) degrees, gamma = 87.27(3) degrees at 20 degrees C (M = W). The salts (CO)(3)M(en)(2)[2,2,2-crypt-K](4)[1-M(CO)(3)(eta(4)-Pb(9))].2.5en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 2, a = 16.319(3) A, b = 17.078(3) A, c = 24.827(5) A, alpha = 71.82(3) degrees, beta = 83.01(3) degrees, gamma = 81.73(3) degrees at -133 degrees C (M = Mo) and a = 16.283(4) A, b = 17.094(3) A, c = 24.872(6) A, alpha = 71.62(2) degrees, beta = 82.91(2) degrees, gamma = 81.35(2) degrees at -153 degrees C (M = W). The [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions were also characterized in liquid NH(3) solution by (119)Sn, (117)Sn, and (95)Mo NMR spectroscopy. Unlike their fluxional precursor, nido-Sn(9)(4-), NMR studies show that the [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions are rigid on the NMR time scale. All possible inter- and intraenvironmental couplings, J((119,117)Sn-(119,117)Sn), J((119,117)Sn-(183)W), and one J((119,117)Sn-(95)Mo) coupling, have been observed and assigned. Complete spin-spin coupling constant assignments were achieved by detailed analyses and simulations of all spin multiplets that comprise the (119)Sn and (117)Sn NMR spectra and that arise from natural abundance tin isotopomer distributions and from natural abundance (183)W, in the case of [1-W(CO)(3)(eta(4)-Sn(9))](4-). Both the solid state and solution structures of the [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions are based on a closo-bicapped square antiprismatic structure in which the transition metal occupies a cap position. The cluster structures are consistent with Wade's rules for 22 (2n + 2) skeletal electron systems. Electron structure calculations at the density functional theory (DFT) level provide fully optimized geometries that are in agreement with the experimental structures. Complete assignment of the NMR spectra was also aided by GIAO calculations. The calculated vibrational frequencies of the E(9)(4-) and [1-M(CO)(3)(eta(4)-E(9))](4-) anions are also reported and are used to assign the solid-state vibrational spectra of the [1-M(CO)(3)(eta(4)-E(9))](4-) 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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 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".