Synthesis, structure, and reactivity of AlMe2(1-Me-CB11F11): An AlMe2+ cation-like species bonded to a superweak anion

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

“…[11] The BÀCl bonds located in the upper belt are on average slightly longer than in the lower belt. Also the BÀB distances between B1 and the atoms B (2)(3)(4)(5)(6) and those between the atoms B(2-6)ÀB(2-6) are longer than in the lower belt. The elongation of these bonds can be explained by a steric repulsion between the methyl groups and the chlorine atoms from the upper belt.…”

“…The sum of the angles around C1 is 360.0(4)8 which is expected for a free trityl cation and is also observed in crystal structures of the [Ph 3 C] + cation with other weakly coordinating anions ([B 12 Cl 12 ] 2À , [11] [Me 3 NB 12 F 11 ] À , [12] [1-H-CB 11 Br 11 ] [14] ). 11 ) crystallizes in the space group P2 1 /n ( Figure 5), and the silicon atom Si1 of the [Et 3 Si] + cation is coordinated to the Cl6 atom (Si1ÀCl6: 229.3(1) pm) at the lower five-ring belt of the [Me 3 NB 12 Cl 11 ] À anion. This coordination leads to a slight increase of the length of the corresponding boron-chlorine bond (B7ÀCl6: 185.1(3) pm).…”

“…Among the weakly coordinating anions, the boron-clusterbased 1-carba-closo-dodecaborate anions [1-R-CB 11 Y 5 X 6 ] À (R = H, alkyl; Y = H, Me, Hal; X = H, Me, Hal) and the closo-dodecaborate anions [B 12 X 12 ] 2À (X = H, Hal) exhibit exceptional chemical, electrochemical, and thermal stability. [1] They stabilize highly reactive cations (for example, [R 3 Si] + , [2] [R 2 Al] + , [3] [C 60 ] + [4] ), are part of the Brønsted superacids H(R-CB 11 X 5 Y 6 ) [4] or H 2 (B 12 X 12 ), [5] respectively, and form the neutral compounds 1-R-CB 11 X 5 Y 6 (for example, for R, X, Y = Me; [6] R = H, X = F or CF 3 , Y = CF 3 or F [7] ) or B 12 X 12 , [8] which are themselves very strong oxidizing agents. Because of their superior chemical and physical properties the halogenated carborates belong to the most weakly coordinating anions.…”

“…[12] These anions combine the single negative charge with the advantages (for example, cheap and simple synthesis) of the dodecaborates. Although the preparation of the [Ph 3 C] + and [AlEt 2 ] + salts of these anions showed their ability to perform as weakly coordinating anions, their chemistry was not explored any further, presumably because of the lack of fluorination equipment in most laboratories. Attempts to prepare the respective fully chlorinated and brominated [R 3 NB 12 Cl 11 ] À and [R 3 NB 12 Br 11 ] À anions were hitherto unsuccessful.…”

Infrared-Driven Charge Transfer in Transition Metal B12F12 Clusters

“…For this reason, B 12 F 12 2─ has been called a "weakly coordinating" or "superweak" anion. 25,[27][28][29][30] While a good deal is known about the structures and properties of polyboron chlorides, bromides, and iodides, 18 the literature concerning experimental investigation of polyboron fluoride clusters is relatively sparse. 16,[18][19][20][21][22] For the most part, structural characterization of small boron halide clusters has been achieved by gas-phase electron diffraction or X-ray crystallography of low-temperature B n F m crystals.…”