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

The synthesis of iodine(I) complexes with either benzoimidazole or carbazole-derived sp2 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 eight 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.