CT-adduct vs. pyridinium polyhalide salt formation in the reactions between polypyridyl donors and dihalogens: reactivity of 1,4-di-(3'-pyridylethynyl)benzene towards Br2 and I2”

ARAGONI, MARIA CARLA;ARCA, MASSIMILIANO;Coles S. J;Devillanova F. A;Hursthouse M. B;Coles S. L;ISAIA, FRANCESCO;LIPPOLIS, VITO;Mancini A.

2011-01-01

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Abstract

The reactions of 1,4-di-(3′-pyridylethynyl)benzene (L) with I2 and Br2 in CH2Cl2 afforded 1 and 2, respectively: the former compound features CT-adduct units L·2I2 connected by a third diiodine molecule to give (L·I6)∞ chains, while the latter is a salt where the monocation HL′+, derived from the N-protonation of a pyridine unit and dibromination of the triple C–C bonds of L, is counterbalanced by an asymmetric tribromide. The isolation of 1 and 2 provides a striking example of how the competition between the Lewis and Brønsted–Lowry basicity of polypyridyl donors can be exploited for the rational design of either neutral or charged building blocks of supramolecular architectures.