The Search for Tricyanomethane (Cyanoform)

Šišak, Dubravka; McCusker, Lynne B.; Buckl, Andreas; Wuitschik, Georg; Wu, Yi Lin; Schweizer, W. Bernd; Dunitz, Jack D.

doi:10.1002/chem.201000559

Cited by 15 publications

(10 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been reported that TCM- ion derives from a super acid ( pKa = − 5). 16 The spectrum is that of the isolated anion as proved by its concentration independence down to 0.005 M (not shown here). This peak at 2172 cm −1 is located atop of the broad and weak combination band of water.…”

Section: Resultsmentioning

confidence: 72%

Differential Hydration of Tricyanomethanide Observed by Time Resolved Vibrational Spectroscopy

2012

View full text Add to dashboard Cite

The degenerate transition corresponding to asymmetric stretches of the D3h tricyanomethanide anion, Cfalse(CNfalse)3-, in aqueous solution was investigated by linear FTIR spectroscopy, femtosecond pump-probe spectroscopy, and 2D IR spectroscopy. Time resolved vibrational spectroscopy shows that water induces vibrational energy transfer between the degenerate asymmetric stretch modes of tricyanomethanide. The frequency-frequency correlation function and the vibrational energy transfer show two significantly different ultrafast time scales. The system is modeled with molecular dynamics simulations and ab-initio calculations. A new model for theoretically describing the vibrational dynamics of a degenerate transition is presented. Microscopic models, where water interacts axially and radially with the ion, are suggested for the transition dipole reorientation mechanism.

show abstract

Section: Resultsmentioning

confidence: 72%

Differential Hydration of Tricyanomethanide Observed by Time Resolved Vibrational Spectroscopy

2012

View full text Add to dashboard Cite

show abstract

“…Comparison of Superflip solutions for 14 structures (nine containing light atoms only and five with heavy scatterers) plotted (a) according to reflection overlap and number of atoms/asymmetric unit, and (b) according to the percent of fully interpretable solutions found. Four structures containing heavy scatterers (Liu et al, 2011;Š išak, McCusker, Buckl et al, 2010) have also been included to put the results presented in this manuscript in perspective.…”

Section: Figurementioning

confidence: 99%

Solving the structures of light-atom compounds with powder charge flipping

et al. 2014

View full text Add to dashboard Cite

While the powder charge flipping (pCF) algorithm has been applied successfully to a variety of inorganic compounds, reports on its application to organic structures, in particular those consisting of light atoms only, are rare. To investigate the reason for this apparent incongruity, a series of light‐atom structures were tested using the pCF algorithm implemented in the program Superflip. The data sets, which covered varying degrees of reflection overlap, had resolutions of approximately 1 Å, and the structures ranged from 40 to 136 atoms per unit cell. Both centrosymmetric and noncentrosymmetric structures were investigated. A modified pCF approach, which was developed in a separate study, was tested on several compounds whose structures could not be solved by applying the basic pCF algorithm in Superflip. The results show that organic structures with no heavy atoms and low symmetry do indeed test the limits of the pCF algorithm in Superflip. The study has allowed a few guidelines for approaching such problems to be formulated.

show abstract

“…We have now tested this procedure on several data sets (Table 11), collected on both organic and inorganic materials, and it seems to work. The straightforward approach with = 0.3, B iso = 0-1, HM = 20-5, = AUTO , 500 cycles and 100 runs produced interpretable maps that could be identified with the R SF value for a Ba phenylboronate (novel structure, sample kindly provided by Danielle Laurencin, University of Montpellier, France), for the molecular sieve ZrPOF-EA (Liu et al, 2011), for two tricyanomethane derivatives (Š išak, McCusker, Buckl et al, 2010), and for the sugars dl-ribose (sample kindly provided by J. D. Dunitz, ETH Zurich) and d-arabinose (Takagi & Jeffrey, 1977). Three organic structures, all crystallizing in the space group P2 1 like d-ribose, required starting phases from an approximate model.…”

Section: General Guidelinesmentioning

confidence: 99%

“…For example, phase information derived from high-resolution transmission electron microscopy (HRTEM) images can be added in reciprocal space, or a structure envelope (Brenner et al, 1997) can be imposed on the electron density map in real space. Although most applications to date have involved inorganic materials, in particular microporous solids (Dong et al, 2007;Liu et al, 2009Liu et al, , 2011Massü ger et al, 2007;Sun et al, 2009;Xie et al, 2009;Kubli et al, 2012), some organic compounds have also been studied (Baerlocher, McCusker & Palatinus, 2007;Š išak, McCusker, Buckl et al, 2010). Because the program is relatively new, the selection of input parameter values for the powder charge-flipping (pCF) algorithm in Superflip has necessarily been rather subjective and arbitrary.…”

Section: Introductionmentioning

confidence: 99%

Optimizing the input parameters for powder charge flipping

et al. 2012

Self Cite

View full text Add to dashboard Cite

Over the past few years, the powder charge‐flipping algorithm has proved to be a useful one for structure solution from powder diffraction data, so a semi‐systematic study of the effect of the different input parameters on its success has been performed. Two data sets were studied in these tests: a zirconium phosphate framework material and D‐ribose. The Superflip input parameters tested were the reflection overlap factor, the intensity repartitioning frequency, the isotropic displacement parameter, the threshold for charge flipping and the number of cycles/runs. By varying the values of these parameters within sensible ranges, an optimized set could be found for the zirconium phosphate case, but no combination of parameters allowed the D‐ribose structure to be solved. Reasoning that starting with nonrandom phases might help, an approximate (but incorrect) structure was generated using the direct‐space global‐optimization method implemented in the program FOX. This structure was then used to calculate initial phase sets for Superflip by allowing the calculated phases to vary in a random fashion by a user‐defined percentage. With such phases and reoptimized input parameters, some fully interpretable solutions with the correct symmetry could be produced, even with fairly low resolution data. Unfortunately, it was not possible to recognize these solutions using the Superflip R values, so other criteria were sought. Both cluster analyses and maximum entropy calculations of the solutions were performed, and the latter, in particular, look very promising. A set of guidelines derived from these two structures could be applied successfully to a further two inorganic and seven organic structures.

show abstract

The Search for Tricyanomethane (Cyanoform)

Cited by 15 publications

References 37 publications

Differential Hydration of Tricyanomethanide Observed by Time Resolved Vibrational Spectroscopy

Differential Hydration of Tricyanomethanide Observed by Time Resolved Vibrational Spectroscopy

Solving the structures of light-atom compounds with powder charge flipping

Optimizing the input parameters for powder charge flipping

Contact Info

Product

Resources

About