(IUCr) Crystallography Journals Online checkcif report

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Acta Cryst. (2004). E60, o89-o91 [ doi:10.1107/S160053680302840X ]

1-Amino-3-ammonioguanidinium dichloride

A. van der Lee and M. Barboiu

Online 19 December 2003

Key indicators

Single-crystal X-ray study
T = 293 K
Mean (N-C) = 0.004 Å
R factor = 0.052
wR factor = 0.090
Data-to-parameter ratio = 19.2

checkCIF/PLATON results

No syntax errors found




Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT353_ALERT_3_C Long    N-H Bond (0.87A)   N4     -   H10      =       1.02 Ang.  
PLAT701_ALERT_1_C Bond    Calc    1.408(4), Rep    1.414(4), Dev..       1.50 Sigma 
              N4   -N5      1.555   1.555

Author Response: The hydrogen atom was clearly found by a difference Fourier synthesis at the specified distance from N4. Placing it geometrically gave a significant worse agreement factor. Moreover, from the presence of two Cl ions it is clear that the di-aminoguanidinium ion should be protonated to give a formal charge of 2+. Assigning the positive density in the difference Fourier map to a proton was the only possibility to get an overall neutral charge, although it may be a bit displaced.

PLAT721_ALERT_1_C Bond    Calc     0.88065, Rep     0.86800, Dev.        0.01 Ang.  
              N4   -H9      1.555   1.555                                       
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          3       
              Cl                                                                

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion