Chemistry of solutions in liquid sulfur dioxide

Crown Ether Complexes of Alkali‐Metal Chlorides from SO2

“…The salts LiCl (99.9 %), NaCl (99.9 %), KCl (99.99 %), RbCl (99.8 %) and CsCl (99.5 %) were commercially purchased from Sigma Aldrich and dried under vacuum at 150 8Cf or at least 3h.12-Crown-4 (97 %) was purchased from Acros Organics. Regarding the negligible effect owing to low absorption coefficients, the absorption correction was omitted for those crystals (compounds 4,7,8). [30] Solvent SO 2 (Air Liquide, 99.999 %) was dried over CaH 2 and distilled directly into the reaction vessel through avacuum line.…”

“…The structure of [Rb(12-crown-4) 2 (SO 2 )]Cl·4SO 2 (5)i si sotypic to [K(12-crown-4) 2 (SO 2 )]Cl·4SO 2 (4). The O crown ÀRb distances measured between 284.2(2) and 315.7(1) pm and the O,O'-coordinated SO 2 molecule was also found to have longera tomic distances (306.7(1) and 324.0(2) pm) than those in compound 4,w hich nicely depicts the larger ionic radius of Rb + .T he 1 H and 13 C{ 1 H} NMR spectra revealed the same tendency as observed for the sandwich-type complexes of compounds 3 and 4.I nt he 1 HNMR spectrum of compound 5,t he signal undergoes as ignificant upfield shift from d = 4.24 ppm in the free ligand to d = 3.92 ppm.…”

“…[2] In particular,c ompounds with covalent-bondingc haracter,s uch as AlCl 3 and BCl 3 ,a re significantlym ore soluble in SO 2 than saltsw ith at ypical ionic lattice,s uch as LiCl and NaCl. [3,4] Numerous reported coordination compounds with SO 2 as aligand display avariety of bonding modes. [5] S-( e.g.,[ Mn(C 5 H 5 )(CO 2 )(SO 2 )]) [6] and S,O-coordination (e.g.,[ Mo(CO) 3 (phen)(SO 2 )],p hen = phenanthroline) [7] were observed for electron-rich complexes.…”

“…[18] In contrast, reactions of SO 2 with salts that contain strongly coordinating anions, such as the alkali-metalc hlorides, have only scarcely been investigatedowing to their low solubility in SO 2 . [4] Organic compounds, for example, amines [19] and glycols, [20] are easily miscible with SO 2 and find applicationsa s absorber materials for flue-gas desulfurization. [21] In particular, room-temperature ionic liquids basedo na lkylammonium salts have proved to be valuable for the reversibler emoval of sulfur from flue gas.…”

“…Liquid sulfur dioxide has been established as one of the most important inorganic, aprotic and polar solvents for synthetic organic and inorganic chemistry . In particular, compounds with covalent‐bonding character, such as AlCl 3 and BCl 3 , are significantly more soluble in SO 2 than salts with a typical ionic lattice, such as LiCl and NaCl . Numerous reported coordination compounds with SO 2 as a ligand display a variety of bonding modes .…”