The potential of pyrimidines to serve as ditopic halogen-bond acceptors is explored. The halogen-bonded cocrystals formed from solutions of either 5,5′-bipyrimidine (C 8 H 6 N 4 ) or 1,2-bis(pyrimidin-5-yl)ethyne (C 10 H 6 N 4 ) and 2 molar equivalents of 1,3-diiodotetrafluorobenzene (C 6 F 4 I 2 ) have a 1:1 composition. Each pyrimidine moiety acts as a single halogen-bond acceptor and the bipyrimidines act as ditopic halogen-bond acceptors. In contrast, the activated pyrimidines 2- and 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine (C 14 H 13 N 3 ) are ditopic halogen-bond acceptors, and 1:1 halogen-bonded cocrystals are formed from 1:1 mixtures of each of the activated pyrimidines and either 1,2- or 1,3-diiodotetrafluorobenzene. A 1:1 cocrystal was also formed between 2-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine and 1,4-diiodotetrafluorobenzene, while a 2:1 cocrystal was formed between 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine and 1,4-diiodotetrafluorobenzene.
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5-{[4-(Dimethylamino)phenyl]ethynyl}pyrimidine–1,2,3,5-tetrafluoro-4,6-diiodobenzene (1/2)
The treatment of 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine with a threefold excess of 1,2,3,5-tetrafluoro-4,6-diiodobenzene in dichloromethane solution led to the formation of the unexpected 1:2 title co-crystal, C 14 H 13 N 3 ·2CF 4 I 2 . In the extended structure, two unique C—I...N halogen bonds from one of the 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecules to the pyrimidine N atoms of the 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine molecule generate [110] chains and layers of these chains are π-stacked along the a- axis direction. The second 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecule resides in channels formed parallel to the a -axis direction between stacks of 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine molecules and interacts with them via C—I...π(alkyne) contacts.
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- PAR ID:
- 10349777
- Date Published:
- Journal Name:
- IUCrData
- Volume:
- 7
- Issue:
- 4
- ISSN:
- 2414-3146
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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