The Syntheses of Carbocations by Use of the Noble-Gas Oxidant, [XeOTeF₅][Sb(OTeF₅)₆]:  The Syntheses and Characterization of the CX₃⁺ (X = Cl, Br, OTeF₅) and CBr(OTeF₅)₂⁺ Cations and Theoretical Studies of CX₃⁺ and BX₃ (X = F, Cl, Br, I, OTeF₅)

Abstract

The CCl(3)(+) and CBr(3)(+) cations have been synthesized by oxidation of a halide ligand of CCl(4) and CBr(4) at -78 degrees C in SO(2)ClF solvent by use of [XeOTeF(5)][Sb(OTeF(5))(6)]. The CBr(3)(+) cation reacts further with BrOTeF(5) to give CBr(OTeF(5))(2)(+), C(OTeF(5))(3)(+), and Br(2). The [XeOTeF(5)][Sb(OTeF(5))(6)] salt was also found to react with BrOTeF(5) in SO(2)ClF solvent at -78 degrees C to give the Br(OTeF(5))(2)(+) cation. The CCl(3)(+), CBr(3)(+), CBr(OTeF(5))(2)(+), C(OTeF(5))(3)(+), and Br(OTeF(5))(2)(+) cations and C(OTeF(5))(4) have been characterized in SO(2)ClF solution by (13)C and/or (19)F NMR spectroscopy at -78 degrees C. The X-ray crystal structures of the CCl(3)(+), CBr(3)(+), and C(OTeF(5))(3)(+) cations have been determined in [CCl(3)][Sb(OTeF(5))(6)], [CBr(3)][Sb(OTeF(5))(6)].SO(2)ClF, and [C(OTeF(5))(3)][Sb(OTeF(5))(6)].3SO(2)ClF at -173 degrees C. The CCl(3)(+) and CBr(3)(+) salts were stable at room temperature, whereas the CBr(n)(OTeF(5))(3-n)(+) salts were stable at 0 degrees C for several hours. The cations were found to be trigonal planar about carbon, with the CCl(3)(+) and CBr(3)(+) cations showing no significant interactions between their carbon atoms and the fluorine atoms of the Sb(OTeF(5))(6)(-) anions. In contrast, the C(OTeF(5))(3)(+) cation interacts with an oxygen of each of two SO(2)ClF molecules by coordination along the three-fold axis of the cation. The solid-state Raman spectra of the Sb(OTeF(5))(6)(-) salts of CCl(3)(+) and CBr(3)(+) have been obtained and assigned with the aid of electronic structure calculations. The CCl(3)(+) cation displays a well-resolved (35)Cl/(37)Cl isotopic pattern for the symmetric CCl(3) stretch. The energy-minimized geometries, natural charges, and natural bond orders of the CCl(3)(+), CBr(3)(+), CI(3)(+), and C(OTeF(5))(3)(+) cations and of the presently unknown CF(3)(+) cation have been calculated using HF and MP2 methods have been compared with those of the isoelectronic BX(3) molecules (X = F, Cl, Br, I, and OTeF(5)). The (13)C and (11)B chemical shifts for CX(3)(+) (X = Cl, Br, I) and BX(3) (X = F, Cl, Br, I) were calculated by the GIAO method, and their trends were assessed in terms of paramagnetic contributions and spin-orbit coupling.

Energetics of hydride and electron pair attachment to EX30/+ (E=B, C, Al, Si and X=F, Cl, Br, I) and the study of bonding trends among EX30/+, EX32−/−, and EX3H−/0 by use of ELF and NBO analyses

“…In addition, the structure of the OTeF 5 substituted carbocation, C(OTeF 5 ) 3 + , has recently been obtained from the crystal structure of [C(OTeF 5 ) 3 ][Sb(OTeF 5 ) 6 ]Á3SO 2 ClF [1]. All four cations have local D 3h symmetries in their crystal structures.…”

“…While solid-state structural data for trihalomethyl cations had been previously lacking, electronic structure calculations using various quantum mechanical methods had been used to predict the bonding and chemical properties for www.elsevier.com/locate/fluor Journal of Fluorine Chemistry 125 (2004) 1563-1578 the isoelectronic CX 3 + [1][2][3][4][5][6][7][8][9][10][11][12][13] and BX 3 [1,2,5,[14][15][16][17][18][19]] (X = F, Cl, Br, I) series and related isovalent species such as AH 2 X + and YH 2 X (X = F, Cl, Br, I; A = C, Si, Ge, Sn, Pb; Y = B, Al, Ga, In, Tl) [5]. Results abound for species where X = F [1,2,7,[9][10][11][14][15][16][17][18][19][20][21] or Cl [1,2,6,7,[12][13][14][15][16]…”

Can Weakly Coordinating Anions Stabilize Mercury in Its Oxidation State +IV?

“…A variety of suitable reagents for oxidations are available, including Xe(OTeF 5 ) 2 , [31,40] Xe(OTeF 5 ) 4 , [34] or the recently reported [XeOTeF 5 ][Sb(OTeF 5 ) 6 ]. [43] B(OTeF 5 ) 3 is also a well-known reagent for transferring the OTeF 5 ligand. [31] It could be supplemented by a suitable oxidizing agent.…”

Oxidation of CS2 by AsBr4+: The Unexpected Formation of the Simple CS2Br3+ Carbenium Ion

“…[19] Also the crystal structures of its lighter homologues CCl 3 + and CBr 3 + have been published very recently. [20] In most simple and reactive carbocations, fluoro- 4 ] À (R = C(CF 3 ) 3 ), [21] which is also used in the present work. In our continuing studies of the reactivity of the EX 2 + ions (E = P, As) we fortuitously synthesized and fully characterized the novel CS 2 Br 3 + carbocation by the 4 e À oxidation of CS 2 with AsBr 4 + .…”

“…The detailed assignment of the cation bands is given in Table 3. The band at 916 cm À1 is assigned to the CÀBr stretch and may be compared to the CÀ Br vibration in the CBr 3 + ion that was calculated by Schro- [20] …”