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

Abstract

The alkali metal salts (M = Li, Na, K, Rb, Cs) of the perchlorinated closo-dodecaborate [B(12)Cl(12)](2-) were prepared by reaction of [NEt(3)H](2)[B(12)Cl(12)] with the corresponding alkali metal hydroxide. Crystallization of M(2)[B(12)Cl(12)] from liquid sulfur dioxide gave the sulfur dioxide complexes [Li(2)(SO(2))(8)][B(12)Cl(12)], Na(2)[B(12)Cl(12)].4SO(2), K(2)[B(12)Cl(12)].8SO(2), Rb(2)[B(12)Cl(12)].4SO(2), and Cs(2)[B(12)Cl(12)].SO(2), which were characterized by single crystal X-ray diffraction. In this work structurally characterized SO(2) complexes of the alkali metal cations K(+) and Rb(+) are reported for the first time. The structure of [Li(2)(SO(2))(8)][B(12)Cl(12)] contains discrete [Li(2)(SO(2))(8)](2+) dications and [B(12)Cl(12)](2-) dianions. Born-Haber cycles based on quantum chemical calculations and estimations of lattice enthalpies for the solid state explain the stability of the discrete dication [Li(2)(SO(2))(8)](2+) in the solid state. Heavier alkali metals form three-dimensional networks containing metal-anion and metal-sulfur dioxide contacts. The crystal structures of Na(2)[B(12)Br(12)].8SO(2) and Na(2)[B(12)I(12)].8SO(2) were determined to investigate the influence of the halogen substituent on the anion. They contain similar three-dimensional network structures. Na(2)[B(12)Br(12)].8SO(2) is isostructural to K(2)[B(12)Cl(12)].8SO(2). In addition the crystal structures of the complexes Na(2)[B(12)I(12)].8SO(2).H(2)O and Na(2)[B(12)H(12)].6SO(2).2H(2)O, which contain water ligands, are reported as well. A comparison of halogenated dodecaborates [B(12)X(12)](2-) (X = F, Cl, Br, I) based on [small nu, Greek, tilde](N-H) stretching frequencies of the corresponding [Oct(3)NH](2)[B(12)X(12)] (X = F - I) salts shows that the fluorinated anion [B(12)F(12)](2-) is the least basic and the iodinated anion [B(12)I(12)](2-) is the most basic anion in this series. These findings are in agreement with those for the corresponding series of perhalogenated carboranes and are explained by the polarizability of the halogen substituent.

Synthesis and Properties of the Weakly Coordinating Anion [Me3NB12Cl11]−

“…(Si···Si: 321.7(9) pm, AE(C-Si-C): 347.4(4)8 and 349.2(4)8). [36] The isolation of crystals containing the hydrogen-bridged [(Et 3 Si) 2 H] + cation and the [Et 3 Si] + cation is in agreement with the observation of several cationic silylium compounds in the 1 H and 29 Si NMR spectra and with the observation of the n as (Si-H-Si) vibration in the solid reaction product.…”

“…[28] The n NÀH values for the [B 12 X 12 ] 2À dianions decrease from X = fluorine to X = iodine and follow the same trend as observed for the halogenated carborate anions. [5,29] The n NÀH value of [HNOct 3 ][Me 3 NB 12 Cl 11 ] fits well into the series of chlorinated 1-carba-closo-dodecaborate and closo-dodecaborate anions, which suggests a similar basicity of the anions ( Cl 11 ]. [11,30] The vibrational spectra of the red solid show the characteristic NO stretching vibration at 2231 cm À1 (Raman) and 2203 cm À1 (IR; Supporting Information, Figure S44).…”

Crown Ether Complexes of Alkali‐Metal Chlorides from SO2

“…However,i nc ontrastt oc ompound 2 there are no additional contacts to the chloride ion. To the best of our knowledge, SO 2 coordination of am etal atom has been reportedt ob et ype O, [10,37] type S,O [7,8] or type m-O,O' in polynuclear complexesw ith bridging SO 2 moieties, [12,47] and exclusively in conjunction with weakly coordinating anions. To the best of our knowledge,t here are no previousr eports on such chlorideion coordination to sulfur atoms in the solid state.…”

“…[8] O-( e.g.,[ Ni(SO 2 ) 6 ] [AsF 6 ] 2 ) [9] and bridging m-O,O'-coordination (e.g.,[ Li(OSO) 6/2 ] [AlCl 4 ] [10] was reported for hard d-and f-block elements and main-group metal atoms. Thel atter require the presence of almost non-coordinating anions, [11] such as [B 12 Cl 12 ] 2À , [12][13][14] [AsF 6 ] À [15] or [Al{OC(CF 3 ) 3 } 4 ] À , [16] to provide sufficients olubility for the correspondings alts. [17] Thus, the resulting" naked" cations are able to interact with the weakly coordinating SO 2 ligandsr ather than with the anion,o ri ns ome cases with both.…”

The Structure of (H3O)2B12F12·6H2O – a CCP Lattice of B12F122– Anions Intercalated with a Nonplanar Network of O–H···O Connected O6 Rings

“…[1][2][3][4][5][6][7] Our hypothesis is that the unique combination of size, shape, high symmetry, thermal stability, and extremely weak Brønsted and Lewis basicity of this anion will lead to unanticipated structures and properties [i.e. unanticipated compared to salts of B 12 H 12 2-, [8][9][10][11] B 12 Cl 12 2-, [12][13][14] B 12 (OH) 12 2-, [15,16] and B 12 (CH 3 ) 12 2- [17] on one hand, and of salts of typical fluoroanions, such as BF 4 -, PF 6 -, Sb 2 F 11 -, SiF 6 2-, and MnF 6 2-, on the other]. For example, K 2 B 12 H 12 exhibits a common antifluorite structure, [10] but K 2 B 12 F 12 exhibits an intermetallic Ni 2 In structure [3] (the B 12 centroids occupy the idealized hexagonal close-packed positions of the In atoms [18] ), which is the first time that this structure has been observed for an ionic compound with a polyatomic anion at ambient temperatures and pressures.…”