On the gas-phase dimerization of negatively charged closo-dodecaborates: a theoretical study.

We have studied the intriguing gas-phase dimerization of the B12In(-) (n = 9, 8) anions to B24I2n(2-) dianions by means of density functional theory calculations. The dimerization of B12I9(-) to B24I18(2-) has been detected experimentally in a previous study (Phys. Chem.

Quantum-chemical and electrochemical investigation of the electrochemical windows of halogenated carborate anions.

The range of electrochemical stability of a series of weakly coordinating halogenated (Hal=F, Cl, Br, I) 1-carba-closo-dodecaborate anions, [1-R-CB(11)X(5)Y(6)](-) (R=H, Me; X=H, Hal, Me; Y=Hal), has been established by using quantum chemical calculations and electrochemical methods. The structures of the neutral and dianionic radicals, as well as the anions, have been optimized by using DFT calculations at the PBE0/def2-TZVPP level. The calculated structures are in good agreement with existing experimental data and with previous calculations.

Bis(triphenyl-λ-phosphanylidene)ammonium hydrogen dichloride.

In the title compound, [(Ph(3)P)(2)N](+)·[Cl-H-Cl](-) or C(36)H(30)NP(2) (+)·Cl(2)H(-), the H atom of the [Cl-H-Cl](-) anion and the N atom of the [(Ph(3)P)(2)N](+) cation are located on a twofold axis, yielding overall symmetry 2 for both the cation and the anion. The central P-N-P angle [144.12 (13)°] of the cation is in the expected range and indicates only weak cation-anion inter-actions.

Collision-induced gas-phase reactions of perhalogenated closo-dodecaborate clusters--a comparative study.

The gas phase reactivity of perhalogenated closo-dodecaborate clusters [B(12)X(12)](2-) (X = F, Cl, Br, I) with N-tetraalkylated ammonium counter ions was investigated by electrospray ionization ion trap mass spectrometry (ESI-IT-MS). Collisions with the background gases introduced a broad variety of gas phase reactions. This study represents the first experimental approach to a new class of boron-rich boron clusters that are not accessible in the condensed phase.

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

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)].

Preparation and characterization of (CNSSS)2(A)2 (A = AsF6(-), SbF6(-), Sb2F11(-)) containing the O2-like 5,5'-bis(1,2,3,4-trithiazolium) dication: the second example of a simple nonsterically hindered main-group diradical that retains its paramagnetism in the solid state.

The reaction of NC-CN with a 1:1 mixture of S(4)(MF(6))(2) and S(8)(MF(6))(2) (M = As, Sb) (stoichiometrically equivalent to four "S(3)MF(6)" units) results in the quantitative formation of S(3)NCCNS(3)(MF(6))(2) [7(MF(6))(2)], which is the thermodynamic sink in this reaction. The Sb(2)F(11)(-) salt 7(Sb(2)F(11))(2) is prepared by the addition of an excess of SbF(5) to 7(AsF(6))(2). Crystal structure determinations for all three salts show that 7(2+) can be viewed as two R-CNS(3)(+) radical cations joined together by a C-C single bond.

Synthesis, characterization, and crystal structures of silylium compounds of the weakly coordinating dianion [B(12)Cl(12)](2-).

The reaction of [Ph(3)C](2)[B(12)Cl(12)] with R(3)SiH (R = Me, Et, iPr) in 1,2-difluorobenzene yielded the corresponding silylium compounds (R(3)Si)(2)B(12)Cl(12) containing the weakly coordinating dianion [B(12)Cl(12)](2-). The products were fully characterized by IR and Raman spectroscopy and by multinuclear ((1)H, (11)B, (13)C, (29)Si) NMR spectroscopy in solution and the solid state (magic angle spinning). (Et(3)Si)(2)B(12)Cl(12) and (iPr(3)Si)(2)B(12)Cl(12) were characterized by X-ray diffraction.

How far can we go? Quantum-chemical investigations of oxidation state +IX.

The highest known oxidation state of any element is +VIII. After the recent discovery of Ir(VIII)O(4) under cryogenic conditions, we have investigated the stability of cationic species [MO(4)](+) (M=Rh,Ir,Mt). Such compounds would formally represent the new oxidation state +IX, which is experimentally unknown so far for the whole periodic table.

Bis(triphenylphosphine)iminium bromide acetonitrile monosolvate.

The title compound, C(36)H(30)NP(2) (+)·Br(-)·C(2)H(3)N, crystallized from a CH(3)CN/OEt(2) solution as an acetonitrile solvate. The central P-N-P angle [142.88 (10)°] is significantly larger than in the corresponding chloride and iodide structures.

Solvate-free bis-(triphenylphosphine)iminium chloride.

The title compound, C(36)H(30)NP(2) (+)·Cl(-), crystallized in the solvate-free form from a CH(3)CN/OEt(2) solution. The chloride anion and the N atom of the [(Ph(3)P)(2)N](+) cation are located on a twofold axis, yielding overall symmetry 2 for the cation. The central P-N-P angle [133.

Silver-ethene complexes [Ag(eta(2)-C2H4)n][Al(OR(F))4] with n = 1, 2, 3 (R(F) = fluorine-substituted group).

Compounds including the free or coordinated gas-phase cations [Ag(eta(2)-C(2)H(4))(n)](+) (n = 1-3) were stabilized with very weakly coordinating anions [A](-) (A = Al{OC(CH(3))(CF(3))(2)}(4), n = 1 (1); Al{OC(H)(CF(3))(2)}(4), n = 2 (3); Al{OC(CF(3))(3)}(4), n = 3 (5); {(F(3)C)(3)CO}(3)Al-F-Al{OC(CF(3))(3)}(3), n = 3 (6)). They were prepared by reaction of the respective silver(I) salts with stoichiometric amounts of ethene in CH(2)Cl(2) solution. As a reference we also prepared the isobutene complex [(Me(2)C=CH(2))Ag(Al{OC(CH(3))(CF(3))(2)}(4))] (2).

How to overcome Coulomb explosions in labile dications by using the [B(12)Cl(12)](2-) dianion.

The dicationic homoleptic lithium-sulfur dioxide complex [Li(2)(SO(2))(8)](2+) in [Li(2)(SO(2))(8)][B(12)Cl(12)] has been characterized by X-ray diffraction; [Li(2)(SO(2))(8)](2+) is stabilized in the solid state by the weakly-coordinating dianion [B(12)Cl(12)](2-) and the high lattice enthalpy of the resulting dication-dianion salt.

Cu[Al(OR(F))4] starting materials and their application in the preparation of [Cu(S(n))]+ (n=12, 8) complexes.

An effective route to stable, almost-"naked" Cu(I) salts of weakly coordinating anions (WCAs) of the type [Al(OR(F))4]- has been developed. Born-Fajans-Haber cycles and theoretical calculations suggest that this methodology is useful for the generation of Cu(I) salts regardless of the larger WCA used. The first homoleptic Cu(I)-arene complex [Cu(1,2-F2C6H4)2](+)[Al{OC(CF3)3}4]- (1), the first Cu(I)-methylenechloride complex [Cu(CH2Cl2)Al{OC(CH3)(CF3)2}4] (2), and the donor-free dimer [CuAl{OCH(CF3)2}4]2 (3) were synthesized in quantitative yields by sonicating Li[Al(OR(F))4] (R(F)=C(CF3)3, C(CH3)(CF3)2, or CH(CF3)2), AgF, and a three-fold excess of CuI in 1,2-F2C6H4 (1) or CH2Cl2 (2, 3).

Silver(I) complexes of the weakly coordinating solvents SO(2) and CH(2)Cl(2): crystal structures, bonding, and energetics of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)].

Pushing the limits of coordination chemistry: The most weakly coordinated silver complexes of the very weakly coordinating solvents dichloromethane and liquid sulfur dioxide were prepared. Special techniques at low temperatures and the use of weakly coordinating anions allowed structural characterization of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(Cl(2)CH(2))(2)][SbF(6)] (see figure). An investigation of the bonding shows that these complexes are mainly stabilized by electrostatic monopole-dipole interactions.

Synthesis and characterization of synthetically useful salts of the weakly-coordinating dianion [B12Cl12]2-.

The closo-dodecahydrododecaborate [NEt3H]2[B12H12] has been prepared on a lab scale by an improved synthesis from cheap and readily available starting materials Na[BH4] and I2 in diglyme (diethylene glycol dimethyl ether). Subsequent chlorination with elemental chlorine in aqueous solution at normal pressure yielded the per-chlorinated weakly coordinating [B12Cl12]2- anion. By simple metathesis reaction a variety of useful salts [cation]2[B12Cl12] (cation=[NEt3H]+, [NBu4]+, Li+, Na+, K+, Cs+) is available.

Trithiatetrazocine cations, [RCN4S3]+; planar sulfur-nitrogen 10pi aromatics.

The reaction of bicyclic sulfur-nitrogen heterocyles RCN 5S 3 (R = F 3C, Ph, Me 2N, 2-FC 6H 4, 2,6-F 2C 6H 3) with [Hg(SO 2) 2][AsF 6] 2 in liquid SO 2 yielded the corresponding trithiatetrazocinium-hexafluoroarsenates [RCN 4S 3][AsF 6] as yellow solids and a red-brown insoluble byproduct with the approximate composition Hg 3N 2. Single crystal structure determinations of the salts and theoretical calculations on the trithiatetrazocine cations [RCN 4S 3] (+) revealed the cations to be planar eight-membered heterocycles. The [RCN 4S 3] (+) cations are the missing link in the series of known valence isoelectronic eight-membered 10pi azocines, that is, [S 4N 4] (2+) and RC(NSN) 2CR.

Accounting for the differences in the structures and relative energies of the highly homoatomic np pi-np pi (n > or = 3)-bonded S2I4 2+, the Se-I pi-bonded Se2I4 2+, and their higher-energy isomers by AIM, MO, NBO, and VB methodologies.

The bonding in the highly homoatomic np pi-np pi (n > or = 3)-bonded S2I42+ (three sigma + two pi bonds), the Se-I pi-bonded Se2I42+ (four sigma + one pi bonds), and their higher-energy isomers have been studied using modern DFT and ab initio calculations and theoretical analysis methods: atoms in molecules (AIM), molecular orbital (MO), natural bond orbital (NBO), and valence bond (VB) analyses, giving their relative energies, theoretical bond orders, and atomic charges. The aim of this work was to seek theory-based answers to four main questions: (1) Are the previously proposed simple pi*-pi* bonding models valid for S2I42+ and Se2I42+? (2) What accounts for the difference in the structures of S2I42+ and Se2I42+? (3) Why are the classically bonded isolobal P2I4 and As2I4 structures not adopted? (4) Is the high experimentally observed S-S bond order supported by theoretical bond orders, and how does it relate to high bond orders between other heavier main group elements? The AIM analysis confirmed the high bond orders and established that the weak bonds observed in S2I42+ and Se2I42+ are real and the bonding in these cations is covalent in nature. The full MO analysis confirmed that S2I42+ contains three sigma and two pi bonds, that the positive charge is essentially equally distributed over all atoms, that the bonding between S2 and two I2+ units in S2I42+ is best described by two mutually perpendicular 4c2e pi*-pi* bonds, and that in Se2I42+, two SeI2+ moieties are joined by a 6c2e pi*-pi* bond, both in agreement with previously suggested models.

The highest bond order between heavier main-group elements in an isolated compound? Energetics and vibrational spectroscopy of S2I4(MF6)2 (M = As, Sb).

The vibrational spectra of S2I4(MF6)2(s) (M = As, Sb), a normal coordinate analysis of S2I4(2+), and a redetermination of the X-ray structure of S2I4(AsF6)2 at low temperature show that the S-S bond in S2I4(2+) has an experimentally based bond order of 2.2-2.4, not distinguishably different from bond orders, based on calculations, of the Si-Si bonds in the proposed triply bonded disilyne of the isolated [(Me3Si)2 CH]2 (iPr)SiSiSiSi(iPr)[CH(SiMe3)2]2 and the hypothetical trans-RSiSiR (R = H, Me, Ph).

Lithium fluoroarylamidinates: syntheses, structures, and reactions.

Lithium fluoroarylamidinates [(Ar(F)C(NSiMe(3))(2)Li)(n).xD] (Ar(F) = 4-CF(3)C(6)H(4), n = 2, D = OEt(2), x = 1 (2a); n = 1, D = TMEDA, x = 1 (4a); Ar(F) = 2-FC(6)H(4), n = 2, D = OEt(2), x = 1 (2b); Ar(F) = 4-FC(6)H(4), n = 2, D = OEt(2), x = 2 (2c); Ar(F) = 2,6-F(2)C(6)H(3), n = 2, D = OEt(2), x = 1 (2d); n = 2, D = 2,6-F(2)C(6)H(3)CN, x = 2 (3d); Ar(F) = C(6)F(5), n= 2, D = OEt(2), x = 1 (2e), n = 1, D = TMEDA, x = 1 (4e); n = 1, x = 2, D = OEt(2) (5e); D = THF (6e)) were prepared by the well-known method from LiN(SiMe(3))(2) and the corresponding nitrile in diethyl ether or by addition of the appropriate donor D to the respective diethyl ether complexes. Depending on the substituents at the aryl group and on the donors D, three different types of structures were confirmed by X-ray crystallography.