How flexible is the water molecule structure? Analysis of crystal structures and the potential energy surface

Abstract

High level ab initio calculations predicted a possibility for energetically low-cost (±1 kcal mol−1) change of the bond angle and bond lengths in wide range,from 96.4° to 112.8° and from 0.930 Å to 0.989 Å, respectively.

Locating hydrogen positions in the autunite mineral metatorbernite [Cu(UO2)2(PO4)2·8H2O]: a combined approach using neutron powder diffraction and computational modelling

“…In both groups, the oxygen atoms of the four water molecules are arranged in a square planar configuration, as shown in Figs. values calculated by Milovanović et al (2020) for over 40 000 crystal structures (96.41-112.81 ) and are close to the ideal bond angles predicted by ). Our proposed bond angle for the copper-coordinating water molecules is considerably more energetically favourable than previously predicted using X-ray methods at 76 (6) (Locock & Burns, 2003).…”

“…However, as deuteration typically decreases the O-H bond length by only 0.5-3% (Grabowski, 2000;Soper & Benmore, 2008), it is believed that any difference in bond length would be minor. It is also worth noting that while two of the four O-H bond lengths fit well within energetically optimal values described by Milovanović et al (2020) (0.930-0.989 Å ), the O( 8)-H(4) and O( 7)-H(2) bonds sit at the higher end, at 0.99 (2) and 0.99 (3) Å , respectively. These bond lengths are similarly high in -and within error of -those predicted by AIRSS, at 0.999 and 0.987 Å , respectively.…”

Intrinsic Contributions of 2′‐Hydroxyl to the Hydration of Nucleosides at the Monomeric Level

“…Finally, concentrating on the trihydrol moiety, another interesting point to note is the bond lengths (O−H) and bond angles (H‐O‐H) of the water molecules (O11, O12, and O13), which vary in 1 in H 2 O, but remain consistent at 0.85 Å and 109.5°, respectively, in 1 in PBS, indicating their higher bond energies and improved uniformity of the valence electron arrangement around the water molecules (Figure 5 g). Meanwhile, for 1 in PBS, if the temperature decreased from 293 to 100 K, the volume of its unit cell shrank by approximately 2.0 % and its configuration remained the same, whereas the bent angle of the three water molecules, unlike the trihydrol moiety in 1 in H 2 O at 100 K, changes to a consistent angle of 104°, which is usually observed for free water molecules and is considered to be the bond angle of the most stable geometry of water molecules (Table S9 in the Supporting Information) [17] . The occurrence of this phenomenon in 1 in PBS may reflect the subtle decline in the dominant confinement of the three water molecules exerted by their surrounding host molecules.…”

“…Recently, Milovanovic et al. discussed the flexibility of such confined water molecules in crystal structures by analyzing their bond angles (H‐O‐H) and bond lengths (H−O) [17] . Based on these data, to further investigate the thermodynamic behavior of these organized trihydrol moieties, the single‐crystal structures of 1 at 273 and 100 K were solved.…”

Refinement of K[HgI3]·H2O using non-spherical atomic form factors

“…The heavy part of the structure is almost unchanged after HAR, as expected. When comparing bonds lengths and angles, the largest difference is observed for the K-O bonds, with a shift of 0.006 Å ; for bond angles, the largest difference between the two refinements is 0.25 for the angle K1-O1-K1 i [symmetry code: (Ichikawa et al, 1991;Milovanović et al, 2020). These dimensions are also consistent with the shape previously described for a water molecule bridging two K + cations in a potassium aryloxide aggregate characterized by neutron diffraction at 100 K: O-H = 0.963 ( 16)-1.009 ( 16) Å and H-O-H = 108.0 (13) (Morris et al, 2007).…”