Eighty-one data sets of organic compounds were selected from various sources and subjected to HAR. The selection was restricted by the following conditions:

Only published data sets. Details, CCDC REFCODES, and assignment to references [(14 , 21 , 23 , 32 , 46 –92 )] are given in table S1.

Only x-ray data sets of at least d = 0.6 Å, to test the effect of resolution.

Temperature of experiment not higher than 140 K.

Purely organic compounds with no metal ions.

Absence of disorder (except water molecules with fractional occupancy in the structures).

No anharmonic motion reported.

Only data available in Acta Crystallographica journals.

With the above restrictions 1–7, we found 60 data sets. The earliest data were from 1988. Because the location of H atoms is particularly important for biology, we selected some additional data (not always in Acta Crystallographica): four amino acids, one dipeptide, six tripeptides, benzene, sucrose, and urea. Because they were used in a recent detailed study of HAR, we also included data for the dipeptide Gly-l-Ala with a slightly lower resolution of 0.657 Å.
Some crystal structures appeared multiple times. For those, the bond lengths used in the analysis were the weighted averages with corresponding weighted SDs. Three of them contained two molecules of the main compound per asymmetric unit (so-called Z′ = 2 structures). In further 23 structures, a solvent molecule (mostly water) was also present. The only atoms appearing other than C, N, O, and H were S (six compounds), P (two compounds), F (one compound), and Cl (four compounds). No H atoms bonded to S or P were present.
Full details of the compounds with relevant information (source for the list of measured reflection data, structure, literature references, HAR details, and previous high-resolution refinement details) are presented in table S1 and in the extended supplementary document “Raw refinement and statistical data” (including representations of the HAR-refined geometries with anisotropic atomic displacement ellipsoids), which has been deposited at www.figshare.com and can be obtained under https://dx.doi.org/10.6084/m9.figshare.3205588.v1.
The inorganic compounds were selected to include hydrogen atoms in quite different environments: bonded to second- to sixth-row elements, in bridging and terminal positions. The data for diborane stemming from a charge-density study (25 ) were made available by C. B. H¨bschle (University of Bayreuth). We measured data for pentaphenyldisiloxane at beamline D3 of storage ring DORIS III at the HASYLAB (Hamburger Synchrotronstrahlungslabor) of DESY (Deutsches Elektronen-Synchrotron) in Hamburg [triclinic 1¯ , Z = 2, a = 9.110(2) Å, b = 10.543(2) Å, c = 13.597(3) Å, α = 94.30(3)°, β = 106.90(3)°, γ = 92.96(3)°, V = 1242.3(5) Å3; T = 8(1) K, λ = 0.5166(2) Å, dmax = 0.45 Å; number of collected reflections = 273,011; number of unique reflections = 25,392; completeness of data = 89.2%; Rint = 0.063]. More details will be reported in a forthcoming study. Data for further inorganic compounds were retrieved from Acta Crystallographica publications (unless otherwise stated) and subjected to HAR: (tetrahydroborato)bis(triphenylphosphine)copper(I) (REFCODE: BHPTCU12) (26 ), [1,1-bis(diphenylphosphino)ferrocene]-carbonyl[dihydrobis(pyrazol-1-yl)-borato]hydridoruthenium(II) acetone solvate (REFCODE: AGOZEC) (35 ), dicarbonyl-cis-dihydrido-trans-bis(triphenylphosphite-O)-iron(II) (REFCODE: QOSZON; data made available by V. Arion, University of Vienna) (36 (link)), and trans-bromohydridobis(triphenylphosphine)-platinum(II) (REFCODE: METRAF) (37 ).