Ionic liquid-assisted synthesis, crystal structures, and electronic structure characterization of novel hybrid organic–inorganic chloride compounds [BMIm] m [ M Cl n ] ( M = Cd, Se, Sn, Bi; n = 4, 6; m = 2, 3)

A series of hybrid organic–inorganic chloride salts containing 1-butyl-3-methylimidazolium, [BMIm] + , cations was synthesized using [BMIm]Cl as an ionic liquid (IL) reaction medium and the corresponding M Cl n salts ( M = Cd, Se, Sn, Bi; n = 2, 3, 4). The resulting compounds, bis(1-butyl-3-methylimidazolium) tetrachloridocadmate(II), (C 8 H 15 N 2 ) 2 [CdCl 4 ] or [BMIm] 2 [CdCl 4 ], ( I ), bis(1-butyl-3-methylimidazolium) hexachloridoselenate(IV), (C 8 H 15 N 2 ) 2 [SeCl 6 ] or [BMIm] 2 [SeCl 6 ], ( II ), bis(1-butyl-3-methylimidazolium) hexachloridostannate(IV), (C 8 H 15 N 2 ) 2 [SnCl 6 ] or [BMIm] 2 [SnCl 6 ], ( III ), and tris(1-butyl-3-methylimidazolium) hexachloridobismuthate(III), (C 8 H 15 N 2 ) 3 [BiCl 6 ] or [BMIm] 3 [BiCl 6 ], ( IV ), were characterized with the aid of the single-crystal X-ray diffraction method at 100 K. Compound ( I ) crystallizes in the monoclinic space group Cc , compounds ( II ) and ( III ) are isostructural and crystallize in the orthorhombic space group P 2 1 2 1 2 1 , and compound ( IV ) crystallizes in the monoclinic space group P 2 1 / c . All four structures contain discrete [CdCl 4 ] 2− , [ M Cl 6 ] 2− ( M = Se or Sn), or [BiCl 6 ] 3− anions charge-balanced by [BMIm] + cations. Ionic interactions and C—H...Cl hydrogen bonds, as well as cation–cation C—H...π and ring–ring contacts, are discussed. The novel compounds are discussed in the context of a literature survey, thereby providing suggestions for future discoveries. Electronic structure calculations yield band gaps of 4.44, 2.91, 2.92, and 3.84 eV for ( I )–( IV ), respectively.