UPPW-9
January 16, 2004

Problem :
        
ICDD 50-2293
C42H78N2O14 - dirithromycin - form I
Wavelength   1.5418 A
Filter : graphite monochromator

Ref : G. Stephenson, Eli Lilly & Company, Indianapolis, IN,
USA, Private Communication (1998)

CAS #: 62013-04-1 - form I
Mwt : 835.08

Search in the Cambridge Structural Database :
Form II polymorph of dirithromycin (semisynthetic macrolide antibiotic)
P21, a=12.254, b=13.123, c=14.507, beta = 103.61, V = 2267.3, Z=2.

2-theta  intensities
7.838  100
9.014   35
10.370  76
11.537  23
12.431   2
12.755   2
13.294  10
13.858   9
14.839  21
15.684  69
16.354  67
17.117  23
18.368  31
19.127   7
20.043  40
20.852  17
21.463   5
21.891  15
23.041  15
23.662  17
24.591  10
25.448   8
25.977   3
26.608   7
29.380   7
30.297   1
31.052   2
31.500   2
33.054   3
33.693   2
34.771   3

RESULTS : Quite discordant...

Most probable cell(s) according to the Participants :

Program            a          b           c        alpha      beta     gamma       V     
                                            M(20)       F 20         Unindexed    Zero   Spacegroup

TREOR (NM)      10.975      12.467      9.804       111.5    114.0        92.7     1108.7
                                           M(17)= 18    F17 = 32 (0.011, 49)                 P1  

TREOR (SG)      14.565      13.310     11.320        90.       95.49      90.      2185.1
                                           M(17)= 9     F17 = 18

AUTOX (VZ)      two phases suggested by using the multiphase indexing option:
   phase 1      14.531       8.528     13.581        90.      106.99      90.      1609.5 (main phase, 25 lines)
   phase 2       9.812       7.671      6.391        90.       90.        90.       481.0 (secondary phase, 6 lines)

McMaille (ALB)  Many possible cells selected for the volume similarity with form II :
Monoclinic      23.0965     4.1352     24.3019       90.      111.826     90.      2154.7
                14.5787    13.2995     11.3447       90.       95.470     90.      2189.6
                15.2576    12.9277     11.3808       90.       96.860     90.      2228.7
                13.4306     7.0222     17.2287       90.       98.271     90.      1607.9 (if the formula is wrong...)
triclinic  :    13.0745     10.6636     9.9254      108.875    62.934     86.288   1128.5


Results from NM and SG (TREOR), Victor Zlokazov (AUTOX) and Armel Le Bail (McMaille).