Iodine(I) and Silver(I) Complexes of Benzoimidazole and Pyridylcarbazole Derivatives

The synthesis of iodine(I) complexes with either benzoimidazole or carbazole-derived sp 2 N -containing Lewis bases is described, as well as their corresponding silver(I) complexes. The addition of elemental iodine to the linear two-coordinate Ag(I) complexes produces iodine(I) complexes with a three-center four-electron (3c-4e) [N — I — N] + bond. The 1 H and 1 H- 15 N HMBC NMR studies unambiguously confirm the formation of the complexes in all cases via the [N — Ag — N] + → [N — I — N] + cation exchange, with the 15 N NMR chemical shift change between 94 to 111 ppm when compared to the free ligand. The single crystal X-ray crystallographic studies on four I + complexes revealed highly symmetrical [N — I — N] + bonds with I — N bond distances of 2.21 - 2.26 Å and N — I — N angles of 177 - 180 ° , whilst some of the corresponding Ag + complexes showed a clear deviation from linearity with N — Ag — N angles of ca. 150 ° and Ag — N bond distances of 2.09 - 2.18 Å.