Oct 172019
 
A hexagonal planar transition-metal complex (M. Garçon, C. Bakewell, G. A. Sackman, A. J. P. White, R. I. Cooper, A. J. Edwards & M. R. Crimmin)

Nature 574, 390–393 (2019). [ doi: 10.1038/s41586-019-1616-2 ]

We report the isolation and structural characterization of a simple coordination complex in which six ligands form bonds with a central transition metal in a hexagonal planar arrangement. The structure contains a central palladium atom surrounded by three hydride and three magnesium-based ligands. This finding has … Read the rest

Aug 302018
 
Unexpected Behaviour in Derivatives of Barluenga's Reagent (L. C. F. Morgan, Y. Kim, J. N. Blandy, C. A. Murray, K. E. Christensen & A. L. Thompson)

Chemical Communications 2018, 54, 9849 – 9852 [doi:10.1039/C8CC05430D]

For the collidine analogues of Barluenga’s Reagent (IPy2BF4) reported, a flat cation is necessary for the generation of a modulated phase, in keeping with the “Ratchet Model” theory [Kim et al., Crystal Growth & Design, 2014, Read the rest

Jun 242018
 
An enhanced set of displacement parameter restraints in CRYSTALS (P. Parois, J. Arnold and R.I. Cooper)

Journal of Applied Crystallography, 2018, 51, 1059-1068. [ doi: 10.1107/S1600576718007100 ]

The implementation and use of a set of new displacement parameter restraints is described. Anisotropic displacement parameters account for a large proportion of the parameters in a crystallographic refinement, but very few restraints for conveniently controlling their values have been implemented in … Read the rest

Nov 012017
 
Some Experimental Aspects of Absolute Configuration Determination using Single Crystal X-​Ray Diffraction (A. L. Thompson, S. F. Jenkinson & G. W. J. Fleet)

Tetrahedron Asymmetry 2017, 28(10), 1330-1336 [doi:10.1016/j.tetasy.2017.08.016]

Students of single crystal X-​ray diffraction are often give advice as to how best to collect their data when attempting absolute configuration determination.  These ‘rules’ often have more grounding in gut-​feeling than evidence.  Thus, in an effort to provide advice and evidence that today’s crystallographers can … Read the rest

Oct 232017
 
HUG and SQUEEZE: using CRYSTALS to incorporate resonant-scattering in the SQUEEZE structure factor contributions to determine absolute structure (R.I. Cooper, H.D. Flack and D.J. Watkin)Acta Crystallographica, 2017, C73, 845–853. [ doi:10.1107/S2053229617013304 ] Using an approximate correction to the X-ray scattering from disordered, resonantly scattering regions of crystal structures we have developed and tested a procedure (HUG) to recover the absolute structure using conventional Flack x refi nement or other post-re finement determination methods.
Jul 062017
 
Will They Co-crystallize? (J.G.P. Wicker,  L.M. Crowley,  O. Robshaw,  E.J. Little,  S. Stokes,  R.I. Cooper  and  S.E. Lawrence)

CrystEngComm, 2017, 19, 5336 – 5340 [ doi:10.1039/C7CE00587C ]

A data-driven approach to predicting co-crystal formation reduces the number of experiments required to successfully produce new co-crystals. A machine learning algorithm trained on an in-house set of co-crystallization experiments results in a 2.6-fold enrichment of successful co-crystal formation in a ranked list of … Read the rest

Jun 202017
 
A publicly available crystallisation data set and its application in machine learning (M. Pillong, C. Marx, P. Piechon, J.G.P. Wicker, R.I. Cooper and T. Wagner)

CrystEngComm, 2017,19, 3737-3745 [ doi:10.1039/C7CE00738H ]

We present here the crystallisation outcomes for 319 publicly available compounds in up to 18 different solvents spread over 5710 individual single solvent evaporation trials. The recorded data is part of a much larger, corresponding in-house database and includes both positive as well as negative crystallisation … Read the rest

Nov 242016
 
Beyond Rotatable Bond Counts: Capturing 3D Conformational Flexibility in a Single Descriptor (J.G.P. Wicker and R.I. Cooper)J. Chem. Inf. Model., 2016, 56 (12), 2347–2352 doi: 10.1021/acs.jcim.6b00565 A new molecular descriptor, nConf20, based on chemical connectivity, is presented which captures the accessible conformational space of a molecule. Currently the best available 2-dimensional descriptors for quantifying the flexibility of a particular molecule are the rotatable bond count (RBC) and the Kier flexibility index.
Sep 232016
 
Hydrogen-​Bonded Homoleptic Fluoride-​Diarylurea Complexes: Structure, Reactivity, and Coordinating Power (L. Pfeifer, K. M. Engle, G. W. Pidgeon, H. A. Sparkes, A. L. Thompson, J. M. Brown & V. Gouverneur)

Journal of the American Chemical Society 2016, 138(40), 13314-13325 [doi:10.1021/jacs.6b07501]

Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5′-​fluoro-​5′-​deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-​F bond from F​. Further understanding of the effect … Read the rest

Sep 192016
 
Why direct and post-refinement determinations of absolute structure may give different results (D.J. Watkin and R.I. Cooper)

Acta. Cryst. (2016) B72 661-683 (Feature Article) [ doi:10.1107/S2052520616012890 ]

Direct determination of the Flack parameter as part of the structure refinement procedure usually gives different, though similar, values to post-refinement methods. The source of this discrepancy has been probed by analysing a range of data sets taken from the recent literature. Most significantly, … Read the rest