Alkali metal-sulfur dioxide complexes stabilized by halogenated closo-dodecaborate anions.

摘要: The alkali metal salts (M = Li, Na, K, Rb, Cs) of the perchlorinated closo-dodecaborate [B12Cl12]2− were prepared by reaction [NEt3H]2[B12Cl12] with corresponding hydroxide. Crystallization M2[B12Cl12] from liquid sulfur dioxide gave complexes [Li2(SO2)8][B12Cl12], Na2[B12Cl12]·4SO2, K2[B12Cl12]·8SO2, Rb2[B12Cl12]·4SO2, and Cs2[B12Cl12]·SO2, which characterized single crystal X-ray diffraction. In this work structurally SO2 cations K+ Rb+ are reported for first time. structure [Li2(SO2)8][B12Cl12] contains discrete [Li2(SO2)8]2+ dications dianions. Born-Haber cycles based on quantum chemical calculations estimations lattice enthalpies solid state explain stability dication in state. Heavier metals form three-dimensional networks containing metal-anion metal-sulfur contacts. structures Na2[B12Br12]·8SO2 Na2[B12I12]·8SO2 determined to investigate influence halogen substituent anion. They contain similar network structures. is isostructural K2[B12Cl12]·8SO2. addition Na2[B12I12]·8SO2·H2O Na2[B12H12]·6SO2·2H2O, water ligands, as well. A comparison halogenated dodecaborates [B12X12]2− (X F, Cl, Br, I) N–H stretching frequencies [Oct3NH]2[B12X12] F – shows that fluorinated anion [B12F12]2− least basic iodinated [B12I12]2− most series. These findings agreement those series perhalogenated carboranes explained polarizability substituent.