Halogen-bonded co-crystal containing 1,3-diiodo-perchlorobenzene and the photoproduct rtct-tetrakis(pyridin-4-yl)cyclobutane resulting in a zigzag topology

The formation and crystal structure of a zigzag network held together by I• • •N halogen bonds is reported. In particular, the halogen-bond donor is 1,3-diiodoperchlorobenzene (C6I2Cl4) while the acceptor is the photoproduct rtct-tetrakis(pyridin-4-yl)cyclobutane (TPCB). Curiously, within the resulting co-crystal (C6I2Cl4)•(TPCB), the photoproduct accepts only two halogen bonds between neighbouring 4-pyridyl rings and as a result behaves as a bent two-connected node rather than the expected four-connected centre. In addition, the photoproduct, TPCB, is also found to engage in C—H• • •N hydrogen bonds, forming an extended zigzag chain.