STRUCTURE TOPOLOGY AND HYDROGEN BONDING IN MARTHOZITE, Cu2+[(UO2)3(SeO3)2O2](H2O)8, A COMPARISON WITH GUILLEMINITE, Ba[(UO2)3(SeO3)2O2](H2O)3
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
The crystal structure of marthozite, Cu 2+ [(UO 2 ) 3 (SeO 3 ) 2 O 2 ] (H 2 O) 8 , a 6.9879(4), b 16.4537(10), c 17.2229(10) A, V 1980.2(3) A 3 , Pbn 2 1 , Z = 4, D calc = 4.37 g/cm 3 , has been solved by direct methods and refined to an R index of 5.7% for 4364 observed (| F o | > 4σ F ) reflections collected with a four-circle diffractometer fitted with Mo K α X-radiation and a CCD detector. There are three unique U sites, each occupied by U 6+ with two short U –O uranyl bonds (1.76–1.82 A) and coordination numbers of [8], [7] and [7], respectively. There are two unique Se sites, each occupied by Se 4+ and coordinated by three O atoms ( Se –O ≈ 1.70 A), forming a triangular pyramid with Se at the apex, indicative of stereoactive lone-pair behavior in Se 4+ . There is one Cu site, occupied by Cu 2+ in octahedral coordination by four (H 2 O) groups ( Cu –H 2 O ≈ 2.0 A) and two O atoms ( Cu –O ≈ 2.4 A). The structural unit is a sheet of composition [(UO 2 ) 3 (SeO 3 ) 2 O 2 ], comprised of chains of edge-sharing (Uϕ n ) polyhedra extending along [100] that are cross-linked in the [001] direction by (SeO 3 ) groups; this sheet is topologically identical to the structural unit in guilleminite, Ba [(UO 2 ) 3 (SeO 3 ) 2 O 2 ] (H 2 O) 3 . Adjacent sheets are linked through interstitial Cu 2+ cations via Cu 2+ –O apical bonds and via H bonds that involve both (H 2 O) groups bonded to Cu 2+ and interstitial (H 2 O) groups not bonded to any cation. The principal differences between marthozite and guilleminite involve the interlayer species. In guilleminite, the Ba atom is centrally positioned with respect to the chain of (UO n ) polyhedra, whereas in marthozite, the Cu 2+ atom is located off the pseudo-mirror plane of the chain of (UO n ) polyhedra. This differential positioning of the interstitial cations results in an intersheet separation in marthozite that is nearly 1 A greater than that in guilleminite, despite the fact that Ba (in guilleminite) is much larger than Cu 2+ (in marthozite). The H-bond arrangement in marthozite is very different from that in guilleminite. In marthozite, there are eight unique interlayer (H 2 O) groups; four of these (H 2 O) groups bond directly to Cu 2+ and four are held in the structure solely by H bonds. In guilleminite, there are two unique interlayer (H 2 O) groups, both of which bond to the interlayer Ba atoms.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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