Solid‐State Photoconversion of a Discrete Mixed Iodine(I) System to a 1D Polymer

The first example of a mixed halogen(I) complex (2), containing three distinct iodine(I) moieties ([N―I―N]+, O―I―N, and [O―I―O]‐) within the same structure was synthesised with 4‐styrylpyridine (4‐stypy) and 3,4,5,6‐tetrafluorophthalate as the stabilising Lewis bases. This complex was observed to be in equilibrium with its respective bis(OIN) complex (1a), with isolated samples of 2 also being found to convert to 1a in solution. Upon UV irradiation of 2, a single‐crystal‐to‐single‐crystal [2+2] cycloaddition reaction was observed, converting the discrete salt 2 to the 1D polymer 5. Complex 5 retained all the iodine(I) moieties from prior to photoconversion, and represents the first example of non‐destructive photoconversion of a halogen(I) complex. To facilitate comparisons to 2 and 5, several additional closely‐related iodine(I) complexes were synthesised, with the iodine(I) complexes characterised by NMR (1H, 1H‐15N HMBC) and SCXRD, as well as by Raman and IR spectroscopy for 2, 5, and their close structural analogue 1a.