Chalcogen Bonding of SO 2 and s‐Block Metal Iodides Near Room Temperature: A Remarkable Structural Diversity

In this contribution we have systematically explored the coordination chemistry of the iodide anion towards SO 2 . While employing large organocations like s‐block metal complexes of crown‐ethers, we discovered a remarkable structural diversity within the herein characterized compounds together with novel architectures of SO 2 solvates. The observed O 2 S ··· I – interactions are observed to be strong enough to determine the crystal packing and dimensionality. In the light of chalcogen bonding, the small molecule SO 2 is introduced as a supramolecular synthon. In the light of a chemistry in non‐aqueous solutions, the ISO 2 – anion is revisited. Chalcogen bonding was established to form one‐dimensional networks in the compounds [Li([12]crown‐4)H 2 O]I · SO 2 ( 1 ), [Na([15]crown‐5)(SO 2 )I] ( 2 ), [K([18]crown‐6)(SO 2 )I] ( 4 ), [NH 4 ([18]crown‐6)]I · SO 2 ( 5 ), [Rb([18]crown‐6)I(SO 2 )] · 2SO 2 ( 6 ) and [Cs([18]crown‐6)(SO 2 ) 2 I] ( 7 ) all of which were obtained by 1:1 complexation of the respective iodide salt and respective crown‐ether in SO 2 solution. Two‐dimensional networks were obtained within the alkaline earth metal compounds [Mg([12]crown‐4) 2 ]I 2 · 4SO 2 ( 9 ) and [Ba 2 ([18]crown‐6) 2 (SO 2 I)(SO 2 ) 2 I 3 ] · SO 2 ( 11 ). The iodosulfite ion ISO 2 – was obtained either by shielding Na + ions with [12]crown‐4, conversion of MgI 2 with [15]crown‐5, conversion of CaI 2 with [18]crown‐6 or conversion of BaI 2 with [18]crown‐6 ( 11 , as aforementioned). [Na([12]crown‐4) 2 ]ISO 2 ( 3 ), [Mg([15]crown‐5)(ISO 2 ) 2 ] ( 8 ) and [Ca 2 ([18]crown‐6)(SO 2 I) 3 ]I 3 ( 10 ) were characterized. In these respective compounds the S ··· I atom distances are considerably shorter than those previously reported. Experimental data around the chemistry of halosulfites is provided. Besides network structures and the iodosulfite formation, an SO 2 ‐rich aggregate could be observed. An SO 2 adduct of the composition [I 2 (SO 2 ) 5 ] 2– was found to be present in [Na([12]crown‐4) 2 ]I · 2.75SO 2 ( 3a ).